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Speaker 1: If I could go back in time to witness any

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Speaker 1: historical moment, going back in time to observe ancient human

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Speaker 1: species would be near the top of my list. How

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Speaker 1: do they build their fires? How do they treat their children?

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Speaker 1: How do they solve problems? And how do they communicate

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Speaker 1: with each other? Do they dance?

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Speaker 2: Do they sing?

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Speaker 1: Do siblings argue with each other? But unfortunately Daniel hasn't

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Speaker 1: figured out time machines yet, so I'm kind of stuck

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Speaker 1: for now. In the absence of time machines. The best

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Speaker 1: we can do right now is search for fossils and

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Speaker 1: try to learn what we can from things like the

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Speaker 1: shape of these fossils in the DNA that's sometimes left behind.

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Speaker 1: And lucky for us, we have doctor Scott Solomon back

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Speaker 1: on the show to tell us about what we've learned

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Speaker 1: so far about ancient hominids, and that's almost as good

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Speaker 1: as a time machine. Welcome to Daniel and Kelly Extraordinary Universe.

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Speaker 3: Hi.

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Speaker 4: I'm Daniel. I'm a particle physicist, but I don't remember

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Speaker 4: the moment that I became human.

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Speaker 1: Hello. I am Kelly Weiner Smith. I study parasites and space,

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Speaker 1: and thank goodness, we don't remember the moment we became

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Speaker 1: human that I'm guessing that that is a biologically, you know,

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Speaker 1: a private moment between your parents.

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Speaker 4: Probably, Oh, I don't know. I don't feel like I

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Speaker 4: was human at birth. You know, I don't feel like

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Speaker 4: I was me at birth. I was just a screaming blob.

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Speaker 4: I think it's fascinating that what emerges from that is

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Speaker 4: a sense of self, a sense of who you are,

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Speaker 4: but you can't really trace it all the way back,

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Speaker 4: like its origins itself are sort of lost to your

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Speaker 4: own memory. I feel like that's similar to how like,

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Speaker 4: as a species, we have some historical memory and some writing,

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Speaker 4: but our own own history is lost. But we were

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Speaker 4: there right like in principle, we saw all this stuff happen,

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Speaker 4: and if we just like kept better records or told

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Speaker 4: each other about it, we would know the answers to

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Speaker 4: all these questions.

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Speaker 2: Yeah.

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Speaker 1: Yeah, And I think this is an interesting thread that

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Speaker 1: sort of wove itself throughout our conversation with Scott Solomon,

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Speaker 1: where I think your definition of human encompasses a lot

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Speaker 1: of the things that modern humans do today, Whereas I

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Speaker 1: think a lot of us would be comfortable thinking of

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Speaker 1: humans as you know, like not too many steps beyond

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Speaker 1: when our you know, most common ancestor with chimpanzees came

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Speaker 1: down from the trees or something like that.

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Speaker 4: No, I'd love to hold like a one million year

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Speaker 4: old stone tool and think about, like, who was the

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Speaker 4: person who made this, because there was a person and

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Speaker 4: they made it, and they like had lives and loves

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Speaker 4: and argued with their siblings and had betrayals and all

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Speaker 4: sorts of stuff and maybe even hummed music to themselves.

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Speaker 4: Who knows, but you know, what was it like to

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Speaker 4: be that person. It feels like a real connection with

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Speaker 4: our past. Yeah, But because we were sloppy in our citations,

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Speaker 4: we don't know who invented the stone tool and who

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Speaker 4: came up with these early ideas, and who first invented

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Speaker 4: music and stuff, and so unfortunately we can't give those

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Speaker 4: people credit.

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Speaker 1: Shame on the early humans they why didn't they develop

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Speaker 1: copyright and patent law much earlier? Clearly that's the peak

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Speaker 1: of humanity.

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Speaker 4: Lab notebooks, man, it's all about lab notebooks. They had

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Speaker 4: taken better notes, we would know. But don't you find

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Speaker 4: it frustrating? Like some of the mysteries in the universe,

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Speaker 4: like what's inside a black hole? Like nobody knows. But

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Speaker 4: these questions like where did we come from? How did

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Speaker 4: this all work? People were there literally m and so

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Speaker 4: somebody knew we just forgot. Yeah, that's like what what

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Speaker 4: are we even doing?

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Speaker 1: That is frustrated, And you know, with black holes, I

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Speaker 1: feel like that's the kind of thing where through equations

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Speaker 1: and good equipment, maybe one day we'll get answers to

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Speaker 1: some of these, but things like did our hominid ancestors

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Speaker 1: argue with their siblings? Like gosh, that would be really

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Speaker 1: hard to get an answer for. You know, some of

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Speaker 1: these like social things, we're never gonna know, and that

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Speaker 1: that is a little devastating.

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Speaker 4: Well, the other thing that's frustrating about this whole field

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Speaker 4: is that there are probably answers waiting for us buried

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Speaker 4: in the earth, Like what fraction of human fossils have

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Speaker 4: we found that exist? You know, some tiny, tiny fraction

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Speaker 4: And if you just knew where to go, like, oh,

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Speaker 4: go dig here, go dig there, the answers are waiting

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Speaker 4: for you. That's incredibly frustrating. In the same way, like

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Speaker 4: the answers are there, if we could just get them

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Speaker 4: out from the earth. If somebody told me that, like

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Speaker 4: the answer to what's inside a black hole? I buried

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Speaker 4: it in a treasure chest somewhere on the planet, like

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Speaker 4: I even go figure it out, Like I would be

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Speaker 4: on the hunt, you know.

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Speaker 1: Right the rest of your life, you would be spending

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Speaker 1: trying to find that.

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Speaker 4: Yeah, exactly, And so that it's so frustrating. These questions

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Speaker 4: are so important and so meaningful, and the evidence is

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Speaker 4: right there in front of us, maybe, but we just

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Speaker 4: can't get to it. Anyway, It's fascinating and wonderful to

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Speaker 4: think about.

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Speaker 1: Well, and I think it's fascinating and wonderful to be

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Speaker 1: the kind of scientists who are searching for those things,

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Speaker 1: because if once in a while you do find some

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Speaker 1: amazing piece of information that suggests, you know, this is

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Speaker 1: probably when we started using fire or something like that.

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Speaker 1: And so we are bringing Scott Solomon back on the show.

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Speaker 1: He did an amazing episode in the past about like

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Speaker 1: current and continuing human evolution, and now we're bringing him

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Speaker 1: here to look to the past. And he's been to

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Speaker 1: a lot of the archaeological sites where we look at

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Speaker 1: ancient humans. He've researched ancient humans a lot for his

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Speaker 1: upcoming book where he looks forward to what evolution might

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Speaker 1: look like on Mars. And we had an absolutely fantastic

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Speaker 1: conversation with Scott today.

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Speaker 4: Yes we did, Thank you, Scott.

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Speaker 1: And Scott suggested to me that we ask our extraordinaries

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Speaker 1: the philosophical question that Daniel and I have essentially just

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Speaker 1: been discussing, which is when did we become human? So

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Speaker 1: let's see what the extraordinaries had to say about that.

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Speaker 5: I think we became human when we started talking technically

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Speaker 5: with the emergence of Homo sapiens, but more likely a

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Speaker 5: couple hundred thousand years later, with the development of culture, symbolism.

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Speaker 4: Art, and language eighty two one hundred thousand years ago,

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Speaker 4: roughly when we developed chins.

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Speaker 5: Evolution continually progresses. There is no specific enduring definition. By

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Speaker 5: way of example, a person with a substantial set of

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Speaker 5: mutations could be defined as a different species at this

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Speaker 5: particular moment. We cannot truly define when a proto human

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Speaker 5: became a human and when we change in a way

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Speaker 5: that a particular specimen is no longer a human being

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Speaker 5: by the standard of today.

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Speaker 2: When we got opposable thumbs. I think we became human

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Speaker 2: when we came down out of the trees began to

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Speaker 2: weave leaves for clothing, learned to use fire to cook

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Speaker 2: our foods, lived in communities, and buried our dead chins

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Speaker 2: and thumbs.

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Speaker 4: Amazing.

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Speaker 1: Yes, we got some fantastic answers, and let's go ahead

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Speaker 1: and see what our expert, Scott Solomon says, and so.

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Speaker 1: Doctor Scott Solomon is a teaching professor in the Department

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Speaker 1: of Biophysics at Rice University. He's the author of Future

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Speaker 1: Humans Inside the Science of Our Continuing Evolution, and his

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Speaker 1: upcoming book, Becoming Martian, How Living in Space Will Change

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Speaker 1: Our Bodies and Minds, is coming out through MIT Press

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Speaker 1: in early twenty twenty six. He hosts the podcast Wild

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Speaker 1: World with Scott Solomon, Taught What Darwin Didn't Know, the

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Speaker 1: Modern Science of Evolution for the Great Courses, and you

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Speaker 1: can check out his streaming series Becoming Martian on Curiosity Stream.

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Speaker 1: Welcome to the show, Scott.

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Speaker 3: Thank you. I'm excited to be back.

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Speaker 4: Thanks for joining us to talk about humanity's do it.

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Speaker 1: Yes, we're so glad you're back. We had so many

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Speaker 1: good comments from the last episode that you were on

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Speaker 1: talking about evolution. I think our community doesn't get enough

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Speaker 1: evolution and they're excited to hear about it. So let's

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Speaker 1: talk about Homo species. So did a lot of ancient

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Speaker 1: humans exist previously? And like, how do we know about

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Speaker 1: how many of them there were? Like do we think

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Speaker 1: there were a lot of them?

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Speaker 3: Yeah, that's a really good question. So, you know, I

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Speaker 3: guess what we're talking about is, you know, species that

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Speaker 3: existed once upon a time that are not our species,

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Speaker 3: Homo sapiens, but that are also you know, close relatives,

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Speaker 3: maybe not in a direct line of descent to us necessarily.

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Speaker 3: That's kind of an interesting thing to talk about. But

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Speaker 3: we know, for example, that we shared a common ancestor

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Speaker 3: with chimpanzees. Chimpanzees are among all the species that are

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Speaker 3: still alive today, they are our closest living relatives, and

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Speaker 3: we know that because mostly of genetic data. So we

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Speaker 3: can look at the DNA of chimpanzees and all of

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Speaker 3: the other apes and primates and everything else that's alive,

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Speaker 3: compare it with our own DNA, and they're actually more

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Speaker 3: closely related to us than they are even to other

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Speaker 3: apes like gorillas, which that part alone kind of always

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Speaker 3: blows my mind. I think it's incredible, Right, you think

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Speaker 3: about chimps and gorillas as being kind of like similar

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Speaker 3: to each other, but chimps are closer to us than

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Speaker 3: to any other living ape other than us.

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Speaker 4: And that's a measure where we just are looking at

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Speaker 4: our DNA and looking at their DNA and calculating some

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Speaker 4: sort of genetic distance.

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Speaker 3: Is that right, that's part of it. It's actually even

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Speaker 3: more complex than that. It's kind of cool because you know,

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Speaker 3: you can just look at, like what percent similarity do

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Speaker 3: we have? And that's one measure of it.

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Speaker 4: Though that measure is weird because we also have like

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Speaker 4: fifty percent DNA in common with bananas.

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Speaker 3: Right exactly, that's right. Well, we do share a common

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Speaker 3: ancestor with bananas, but you have to go back pretty far.

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Speaker 3: So yeah, I mean that's telling us about common ancestry, right,

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Speaker 3: it's telling us about it's like you have some percent

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Speaker 3: of your DNA in common with your cousin and even

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Speaker 3: less in common with your like you know, fourth cousin

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Speaker 3: twice removed or whatever it is. Right, So yeah, if

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Speaker 3: you go back far enough, you can find DNA that

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Speaker 3: we have in common even with like bacteria, there's not much,

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Speaker 3: but there's a tiny bit. So the more that we

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Speaker 3: have in common the more closely related we are in general,

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Speaker 3: but even more specifically, it gets down to like, yeah,

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Speaker 3: but what DNA, what's the DNA doing? And that's when

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Speaker 3: it gets really interesting because then we can actually trace

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Speaker 3: the history of specific genes and see the way that

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Speaker 3: those genes have changed over time, and that allows us

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Speaker 3: to put together kind of a family tree of similarities

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Speaker 3: and track exactly how those parts of our genome have

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Speaker 3: changed over time. So we now know that if it

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Speaker 3: if you went back in time about six to seven

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Speaker 3: million years ago, you would find the common ancestor that

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Speaker 3: we shared with chimpanzees, right.

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Speaker 4: Six or seven million.

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Speaker 3: Nice, six or seven million. So you know, like, you know,

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Speaker 3: I have friends who are historians, and we always joke

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Speaker 3: about like to me, that's like yesterday, right, like six

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Speaker 3: to seven million years that's not so long ago. For

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Speaker 3: an evolutionary biologist or geologists also, you know, they would

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Speaker 3: kind of probably be on the same page with that, like, oh, yeah,

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Speaker 3: it's yesterday. And you know, in the history, you know,

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Speaker 3: if you're used to time scales on the order of

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Speaker 3: hundreds or thousands of years, that's that's a long time ago,

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Speaker 3: and that's and that's fair.

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Speaker 4: Well, my experiments take ten of the minus twenty three seconds,

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Speaker 4: so six million years. It feels like a long time.

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Speaker 3: But not in the history of the universe, right, I

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Speaker 3: mean that's like that's like a blink of an eye.

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Speaker 4: Yeah. Absolutely. So you're saying that we have a common

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Speaker 4: ancestor with chimps and we know that because as we've

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Speaker 4: looked at the DNA and we can project back based

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Speaker 4: on the rate of change and the specific genes that

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Speaker 4: have changed. Have we found a fossil that confirms that

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Speaker 4: or is this just based on DNA?

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Speaker 3: Right? That's great, great question. So, yeah, so we do

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Speaker 3: know a lot about the history of the lineage. Like

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Speaker 3: if you think about that split between so there was

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Speaker 3: a common ancestor of humans and chimpanzees, and then there

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Speaker 3: was some kind of a split that took place, and

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Speaker 3: there was one lineage that eventually led to chimpanzees and

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Speaker 3: another lineage that eventually led to us. And we can

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Speaker 3: talk all about what do we know about that? But

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Speaker 3: your question is like, do we have fossils to help

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Speaker 3: to fill in the picture of what was happening at

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Speaker 3: the time of the common ancestor and maybe right afterwards, right,

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Speaker 3: to help complement what we know from genetics, and the

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Speaker 3: answer is sort of, we do have fossils that go

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Speaker 3: back to around that time. It turns out that that

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Speaker 3: period of time in the part of the world where

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Speaker 3: this was happening, which was like tropical Africa, doesn't, unfortunately,

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Speaker 3: have a ton of great fossils preserved from exactly that time.

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Speaker 3: So that's one of those things where there are some

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Speaker 3: kind of missing little gaps in there. But we've filled

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Speaker 3: in more and more and more, and so we are

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Speaker 3: starting to get a really much more complete picture of

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Speaker 3: not only what was happening around that time, but particularly

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Speaker 3: of all the things that happened subsequently, Like if you

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Speaker 3: track the lineage that eventually led to us, turns out

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Speaker 3: it's way more complicated than people used to think. Right, So,

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Speaker 3: I mean, you can go back to Darwin's time, right.

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Speaker 3: Darwin he obviously, you know, gave us the first notion

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Speaker 3: that we have this evolutionary history, right, and he speculated

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Speaker 3: that we must be closely related to the great apes,

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Speaker 3: the chimpanzees, gorillas, orangutans, And that was based just on

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Speaker 3: like similar anatomy, like if you look at the skeleton

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Speaker 3: of a chimp and a gorilla and a human and

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Speaker 3: a museum or something like that. Like, you know, there's

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Speaker 3: a lot of similarities, there's some pretty clear differences too,

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Speaker 3: but he speculated that they must be our closest living relatives.

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Speaker 3: And then he also speculated that there must be some

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Speaker 3: fossil species that once existed that kind of span that

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Speaker 3: gap between us and the common ancestor that we shared

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Speaker 3: with those apes. And he even predicted that that common

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Speaker 3: ancestor probably lived somewhere in Africa, mainly because that's where

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Speaker 3: the majority of apes great apes, that's chimpanzees, gorillas, or rangutans.

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Speaker 3: So there's a rangutans in Asia, but gorillas and chimps

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Speaker 3: are only in Africa, so that kind of makes you think, Okay,

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Speaker 3: Africa might be where most of this history took place.

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Speaker 3: But at the time, none of those fossils were known,

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Speaker 3: so that was really just kind of like a kind

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Speaker 3: of a wild guess and it took a while, but

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Speaker 3: he turned out to be right.

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Speaker 1: I'd like to talk about how how fossils are formed,

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Speaker 1: but right now, okay, so I'm thinking of a V

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Speaker 1: in my head, and the bottom of the v has

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Speaker 1: our common ancestor, one side has chimpanzees and one side

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Speaker 1: has Homo sapiens, which is us. And we've talked about

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Speaker 1: how there are other Homo species. Also, what's the right

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Speaker 1: way to think about where those lines belong on this

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Speaker 1: V that I have in my head.

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Speaker 3: Yeah, so if you think about that V, you're right,

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Speaker 3: like the point where the two lines come together, that

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Speaker 3: was the common ancestor that we shared with chimpanzees. Something

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Speaker 3: happened and there was a split and then the lineage

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Speaker 3: that eventually led to Homo sapiens. This is where, like

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Speaker 3: I think a lot of people have in their mind

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Speaker 3: that like image of like a hunched over ape that

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Speaker 3: like then there's like slightly standing up a little taller,

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Speaker 3: and then a little taller and eventually like leads to us.

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Speaker 1: And then like on the shirts, so it's true.

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Speaker 3: Yeah exactly, or the bumper stickers or the memes, and

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Speaker 3: then like often you know, like the next step is

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Speaker 3: like you know, hunched over a computer or some or

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Speaker 3: you know, some insert joke here right like about the

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Speaker 3: downfall of humanity however you however you perceive it. But

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Speaker 3: that idea is like, Okay, we the common ancestor that

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Speaker 3: we share with chimpanzees, we think actually looked. It wasn't

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Speaker 3: a chimp, but we think it would have looked more

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Speaker 3: chimp like than human like. That's I think that's a

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Speaker 3: fair statement to make, Like, you know, getting back to

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Speaker 3: the question about do we have fossils, we have fossils

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Speaker 3: from very close to that time that do look much

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Speaker 3: more chimp like than human like. And what I mean

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Speaker 3: by that is if you look at the structure of

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Speaker 3: their bodies. You know, one of the big differences between

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Speaker 3: chimps and us is chimpanzees they don't walk on two feet.

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Speaker 3: They actually can walk on two feet. Technically, if you

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Speaker 3: give chimpanzees two very good pieces of food, like two

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Speaker 3: bananas or something like that, they will hold one in

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Speaker 3: one hand, one in the other hand, and then if

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Speaker 3: you want to get away from the other chimps, you

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Speaker 3: gotta move and you got to walk up right on

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Speaker 3: two So they'll do it. But they look super goofy.

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Speaker 3: And the reason is actually interesting. It's because they can't

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Speaker 3: balance on one foot. So like, you know, if you're sober,

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Speaker 3: you might be able to balance on one foot pretty effectively. Right.

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Speaker 3: That's because our hips and our leg bones and our

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Speaker 3: spine and and our foot. You know, all of that

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Speaker 3: is structured in such a way that enables us to

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Speaker 3: walk in a way that like, for a brief moment,

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Speaker 3: you are kind of balancing on just one foot while

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Speaker 3: the other foot is moving forward. And for a chimp,

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Speaker 3: they have to lean all the way to one side

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Speaker 3: in order to not fall over when they do that,

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Speaker 3: so they look really goofy because they're kind of bodies

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Speaker 3: move and left and right to not fall over. It's

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Speaker 3: not a very effective way of getting around. And so

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Speaker 3: you know, most of the time what they do is

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Speaker 3: that what's called knuckle walking. They walk on all fours,

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Speaker 3: but rather than like putting their hands palm down on

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Speaker 3: the ground, they put their knuckles down in a way

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Speaker 3: that looks super uncomfortable to me, like I would never

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Speaker 3: want to walk around, Like I don't think any toddlers

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Speaker 3: are crawling around with knuckle walking that I've seen, But

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Speaker 3: you know, it's it's an effective way for chimps and

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Speaker 3: gorillas to get around, all right.

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Speaker 4: I have lots of questions about chimps and going bananas

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Speaker 4: and knuckle walking, but I want to hear the answer

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Speaker 4: to Kelly's question, which is about where those splits happen.

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Speaker 4: So after the split between the chimps and the proto humans,

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Speaker 4: are there lots more splits? How do we think about that?

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Speaker 3: Yeah, so basically after the split with you know, the

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Speaker 3: chimp lineage. So those very first species that are on

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Speaker 3: the on our side, on the human side of that split,

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Speaker 3: they would have been walking on their knuckles just the

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Speaker 3: same way that chimpanzees and gorillas do. They weren't really

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Speaker 3: able to walk upright yet. But that starts to happen

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Speaker 3: in the fossil record, so you start to see species

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Speaker 3: that are around five to six million years old that

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Speaker 3: have some of the anatomical features that we use for

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Speaker 3: walking upright in their in their pelvis, their hips, and

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Speaker 3: their spine, in their their legs right. And there's a

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Speaker 3: lot of things that you don't necessarily think about that

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Speaker 3: are associated with walking upright, even like where your your

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Speaker 3: neck the bones in your neck attached to your skull.

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Speaker 3: For us, it's like the bottom of the skull, but

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Speaker 3: if you look at like a dog or another four

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Speaker 3: legged animal, it's behind the skull. So that has to change.

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Speaker 3: There's a lot of anatomical changes that take place to

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Speaker 3: be able to walk upright. And what's really cool in

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Speaker 3: the fossil record is we start to see some of

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Speaker 3: those individual components popping up in these species that are

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Speaker 3: from around that you know, five to six million year

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Speaker 3: old range. But then you get more splits, right, So

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Speaker 3: what's really I think one of the most fascinating aspects

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Speaker 3: of what we now know about human evolution is it

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Speaker 3: wasn't a straight line. You don't have this kind of like,

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Speaker 3: you know, one species that was hunched over leads to

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Speaker 3: one that was a little more upright, to another is

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Speaker 3: a little more upright. They kept having more and more

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Speaker 3: events where there was like one species that split into

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Speaker 3: two more of those v's, and so what we actually

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Speaker 3: see is a whole bunch of different species that are

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Speaker 3: on the human side of the split, but are not

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Speaker 3: necessarily species that ultimately left any descendants. They don't necessarily

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Speaker 3: lead directly to us, but they were more closely related

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Speaker 3: to us than they were to chimpanzees.

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Speaker 4: And when we talk about these splits, it's a nice

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Speaker 4: sort of diagram to have in your head. There's a

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Speaker 4: solid line, it splits is another solid line, But in reality,

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Speaker 4: on the ground, you're talking about populations. Those populations are

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Speaker 4: drifting apart, and so that speciation event takes a little

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Speaker 4: bit of time. Right, You have like populations which starve

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Speaker 4: to differ and then diverge, and then at some point

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Speaker 4: they can't make babies together anymore, and that's when you

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Speaker 4: say they split. Right, it's a bit fuzzier than the

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Speaker 4: cartoon lines were drawing in our minds right.

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Speaker 3: Now, That's exactly right. It is a process, and we

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Speaker 3: can only sort of see it as a process that

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Speaker 3: played out as one lineage that led to two only

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Speaker 3: after a lot of time has passed. And actually we

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Speaker 3: know that sometimes you can start to have a split,

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Speaker 3: but then they might come back together and sort of

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Speaker 3: like reform. So speciation started to happen, but doesn't actually

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Speaker 3: go all the way through to completion.

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Speaker 4: They argued about bananas. Then they got together and decided

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Speaker 4: to share the bananas.

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Speaker 3: That's right. There seems to have been a lot of

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Speaker 3: sharing of bananas in the history of our distant relatives.

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Speaker 1: Bananas are showing up in the show more than I

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Speaker 1: would have guessed human evolution.

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Speaker 4: Of course we're going to go bananas.

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Speaker 1: H love it.

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Speaker 4: So I love this conversation because we keep coming up

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Speaker 4: with more and more questions to ask, But I think

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Speaker 4: that finally gives us a chance to unwind back to

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Speaker 4: our original first question, which was, were there are lots

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Speaker 4: of other Homo species previously? How many do we need

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Speaker 4: to think about as we attracting the development of the

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Speaker 4: population that would eventually birth us.

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Speaker 3: Yeah, so we now think that there were something like

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Speaker 3: twenty species, maybe more twenty that existed between the common

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Speaker 3: ancestor that we shared with chimpanzees and our species Homo sapiens.

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Speaker 3: Now the exact number is something that the scientists that

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Speaker 3: study human evolution like to argue about a lot. That's

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Speaker 3: a very kind of contentious. So exactly where to draw

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Speaker 3: those lines between species gets complicated, and partially that has

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Speaker 3: to do with what you were saying annual about, Like

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Speaker 3: the process of speciation isn't always clean. It can be

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Speaker 3: a messy process, and so sometimes it's like, well, is

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Speaker 3: that really a different species? Maybe that was like something

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Speaker 3: that started to become different but maybe didn't proceed all

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Speaker 3: the way to what we would normally consider to be

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Speaker 3: a new species. That could explain part of it, and

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Speaker 3: the other part of it is like any species you

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Speaker 3: look at, you know, there's always variation, Like these guys

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Speaker 3: over there look a little different. These ones over here

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Speaker 3: have an interesting, weird behavior that's different any species right

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Speaker 3: that you look at. So that always makes it a

435
00:21:32,920 --> 00:21:35,240
Speaker 3: little messier when you try to say, like where do

436
00:21:35,320 --> 00:21:39,199
Speaker 3: we draw the boundaries around the edge of what is

437
00:21:39,200 --> 00:21:39,840
Speaker 3: a species?

438
00:21:40,000 --> 00:21:41,760
Speaker 4: And just to clarify, when you say twenty, do you

439
00:21:41,840 --> 00:21:45,919
Speaker 4: mean there's like twenty steps along that line between the

440
00:21:45,960 --> 00:21:48,679
Speaker 4: split between chimps and us or do you mean there

441
00:21:48,680 --> 00:21:51,880
Speaker 4: are twenty sort of parallel tracks there where different kinds

442
00:21:51,880 --> 00:21:53,080
Speaker 4: of Homo species split off.

443
00:21:53,160 --> 00:21:56,200
Speaker 3: Yeah, exactly, it's it's the latter, So it's not it's

444
00:21:56,240 --> 00:21:59,320
Speaker 3: not the case that there was a step wise sequence

445
00:21:59,359 --> 00:22:01,680
Speaker 3: of A led to B, B, led to C, C

446
00:22:01,880 --> 00:22:03,359
Speaker 3: led to D and kind of them all up and

447
00:22:03,400 --> 00:22:07,160
Speaker 3: there's twenty. It's more of picturing like a bush, right,

448
00:22:07,240 --> 00:22:09,480
Speaker 3: So you've got like one stem and you can trace

449
00:22:09,520 --> 00:22:11,480
Speaker 3: that that stem branch is off and you get two

450
00:22:11,520 --> 00:22:14,639
Speaker 3: more leaves over there. But then on another branch just

451
00:22:14,760 --> 00:22:17,680
Speaker 3: over here, there's you know, there's three stems and they

452
00:22:17,680 --> 00:22:20,720
Speaker 3: each have three leaves. So some of these species we're

453
00:22:20,760 --> 00:22:24,040
Speaker 3: living actually at the same time, and that gets to

454
00:22:24,040 --> 00:22:25,960
Speaker 3: be really intriguing to think about.

455
00:22:25,800 --> 00:22:28,119
Speaker 4: The banana politics were bananas.

456
00:22:29,840 --> 00:22:32,800
Speaker 1: So you said we have maybe twenty species, which I'm

457
00:22:32,800 --> 00:22:35,000
Speaker 1: guessing that number must have arisen from a bunch of

458
00:22:35,000 --> 00:22:38,400
Speaker 1: fossils that we found. Do you think we'll be arguing

459
00:22:38,400 --> 00:22:40,920
Speaker 1: over these same twenty forever or do you think there's

460
00:22:40,960 --> 00:22:44,000
Speaker 1: a lot of additional Homo fossils out there that we

461
00:22:44,040 --> 00:22:45,960
Speaker 1: haven't found yet, and maybe we'll end up saying there's

462
00:22:46,000 --> 00:22:47,800
Speaker 1: like a hundred Homo species.

463
00:22:48,000 --> 00:22:49,800
Speaker 3: Yeah, it's a good question. I mean, I think two

464
00:22:49,800 --> 00:22:52,120
Speaker 3: things have been happening in the last few decades, both

465
00:22:52,119 --> 00:22:54,000
Speaker 3: of which are super exciting. One is that, like we

466
00:22:54,080 --> 00:22:58,760
Speaker 3: keep finding new species of you know, I'm gonna say hominis.

467
00:22:58,800 --> 00:23:01,159
Speaker 3: Hominid is the term that we us to describe anything

468
00:23:01,200 --> 00:23:04,560
Speaker 3: on our side of the split from chimpanzees, right, So

469
00:23:04,760 --> 00:23:07,080
Speaker 3: they're not all in the genus Homo. We get to

470
00:23:07,119 --> 00:23:10,040
Speaker 3: the genus Homo at some point in that history, but

471
00:23:10,119 --> 00:23:14,760
Speaker 3: that's a relatively recent development. There are other types of

472
00:23:14,760 --> 00:23:19,960
Speaker 3: hominids that were in different genera, Like Astralopithecus is another one,

473
00:23:20,040 --> 00:23:23,480
Speaker 3: So folks might be familiar with Lucy. That was a

474
00:23:23,520 --> 00:23:29,360
Speaker 3: species known as Astralopithecus aphorensis, and that is another example

475
00:23:29,440 --> 00:23:31,879
Speaker 3: of a hominid, so more on our it's definitely on

476
00:23:31,960 --> 00:23:36,639
Speaker 3: our side of that split, but not in the genus Homo.

477
00:23:37,000 --> 00:23:40,360
Speaker 3: So of all of those, if you add them all up,

478
00:23:40,480 --> 00:23:42,760
Speaker 3: then you can get something like twenty. And so, like

479
00:23:42,840 --> 00:23:45,800
Speaker 3: I said, there's you know, new discoveries that keep happening

480
00:23:45,880 --> 00:23:49,200
Speaker 3: of new species, some of which are in the genus Homo,

481
00:23:49,280 --> 00:23:52,159
Speaker 3: some of which are in some of these other hominid genera.

482
00:23:52,680 --> 00:23:55,119
Speaker 3: So that keeps happening, and that's of course super exciting

483
00:23:55,119 --> 00:23:58,719
Speaker 3: because these are you know, helping fill in the full story.

484
00:23:59,000 --> 00:24:01,520
Speaker 3: But the other thing that keeps happening is we keep

485
00:24:01,560 --> 00:24:04,560
Speaker 3: finding more and more examples of things that we already

486
00:24:04,640 --> 00:24:06,560
Speaker 3: knew about. And one of the things that that has

487
00:24:06,600 --> 00:24:09,719
Speaker 3: been doing is helping us to recognize that sometimes these

488
00:24:09,760 --> 00:24:12,080
Speaker 3: two things that we thought were different, if you find

489
00:24:12,080 --> 00:24:14,800
Speaker 3: something kind of intermediate in between them, you start to

490
00:24:14,840 --> 00:24:17,199
Speaker 3: sort of get a fuller picture and recognize maybe this

491
00:24:17,320 --> 00:24:19,760
Speaker 3: is actually all one thing, and maybe we need to

492
00:24:20,560 --> 00:24:23,520
Speaker 3: you know, not be always splitting everything up, but maybe

493
00:24:23,600 --> 00:24:25,879
Speaker 3: sort of you know, we talk about lumpers and splitters

494
00:24:25,920 --> 00:24:30,479
Speaker 3: in the science of taxonomy, and people tend to you know,

495
00:24:30,560 --> 00:24:33,119
Speaker 3: be more along the lines of kind of Oh, every

496
00:24:33,240 --> 00:24:35,240
Speaker 3: difference I see, I'm going to call a new species

497
00:24:35,280 --> 00:24:38,199
Speaker 3: those or we call those splitters, and the lumpers are

498
00:24:38,200 --> 00:24:40,560
Speaker 3: those that say, well, there's variation within a species. We

499
00:24:40,600 --> 00:24:43,720
Speaker 3: can lump all these together into one and it's always

500
00:24:43,720 --> 00:24:46,080
Speaker 3: a back and forth and their reality is often somewhere

501
00:24:46,119 --> 00:24:48,440
Speaker 3: in between. But yeah, both of those things are happening

502
00:24:48,520 --> 00:24:50,640
Speaker 3: right now, and that, like I said, it's super exciting,

503
00:24:50,680 --> 00:24:53,480
Speaker 3: but it also means it's hard to predict where we're

504
00:24:53,520 --> 00:24:55,440
Speaker 3: going to end up in terms of like how many

505
00:24:55,480 --> 00:24:59,080
Speaker 3: species might there end up being. Yeah, I don't know.

506
00:24:59,160 --> 00:25:01,320
Speaker 1: You're doing such a good job of explaining this stuff, Scott.

507
00:25:01,359 --> 00:25:03,440
Speaker 1: I love hearing you talk about humans. All Right, we're

508
00:25:03,480 --> 00:25:05,120
Speaker 1: gonna take a break and when we come back, we're

509
00:25:05,119 --> 00:25:07,320
Speaker 1: going to hear more about how we go ahead and

510
00:25:07,359 --> 00:25:29,640
Speaker 1: study hominids. And we're back. Scott was telling us that

511
00:25:29,680 --> 00:25:32,960
Speaker 1: there's maybe twenty hominids, but who knows where that number

512
00:25:33,040 --> 00:25:35,360
Speaker 1: is going to be in the next decades, So let's

513
00:25:35,400 --> 00:25:37,960
Speaker 1: go ahead and talk about how we study these. So,

514
00:25:38,040 --> 00:25:40,240
Speaker 1: first of all, you know, you mentioned that a lot

515
00:25:40,280 --> 00:25:43,000
Speaker 1: of these species are found in Africa, but that there's

516
00:25:43,040 --> 00:25:45,639
Speaker 1: not a lot of fossils like what kind of conditions

517
00:25:45,640 --> 00:25:48,240
Speaker 1: do you need to get a fossil in the first place.

518
00:25:48,520 --> 00:25:50,920
Speaker 3: Yeah, I mean when you think about what has to

519
00:25:50,920 --> 00:25:54,359
Speaker 3: happen for a fossil to be not only formed but

520
00:25:54,520 --> 00:25:57,560
Speaker 3: also like found, it's kind of amazing that we have any.

521
00:25:57,640 --> 00:26:00,320
Speaker 3: I mean, first of all, like when something dies, right,

522
00:26:00,800 --> 00:26:03,399
Speaker 3: a lot of times what happens is it gets eaten,

523
00:26:03,640 --> 00:26:06,800
Speaker 3: It gets chewed up, it gets you know, broken down,

524
00:26:06,880 --> 00:26:09,760
Speaker 3: destroyed in some way, either immediately upon death. I mean

525
00:26:09,800 --> 00:26:12,080
Speaker 3: if something gets eaten, right, you know, if you go

526
00:26:12,160 --> 00:26:15,320
Speaker 3: to East Africa today and go on a safari and

527
00:26:15,359 --> 00:26:18,879
Speaker 3: you see the big animals, there's big predators and you know,

528
00:26:19,000 --> 00:26:22,120
Speaker 3: scavengers that live out there, it's amazing that any bones

529
00:26:22,160 --> 00:26:25,680
Speaker 3: have made it at all up until today. So first

530
00:26:25,680 --> 00:26:28,560
Speaker 3: of all, when that individual died, it had to not

531
00:26:29,119 --> 00:26:34,399
Speaker 3: have its bones destroyed. But then later something had to

532
00:26:34,600 --> 00:26:38,320
Speaker 3: preserve them. So one of the places that I've been

533
00:26:38,440 --> 00:26:41,199
Speaker 3: very fortunate to spend some time is a place in

534
00:26:41,240 --> 00:26:45,680
Speaker 3: Tanzania called Olduvai Gorge. And this is a very famous

535
00:26:45,680 --> 00:26:48,800
Speaker 3: site in the history of like our study of human

536
00:26:48,840 --> 00:26:52,200
Speaker 3: evolution because a lot of hominid fossils have been found

537
00:26:52,240 --> 00:26:56,160
Speaker 3: there and I co teach a field course there with

538
00:26:56,200 --> 00:27:00,199
Speaker 3: my colleague here at Rice University, Manuel Domingas Rodrigo, and

539
00:27:00,240 --> 00:27:05,520
Speaker 3: he oversees excavations of fossils at Olduvai Gorge. So we

540
00:27:05,600 --> 00:27:08,919
Speaker 3: take students there and you know, it's incredible because you

541
00:27:09,000 --> 00:27:12,119
Speaker 3: walk around and in this one particular gorge, it's like

542
00:27:12,160 --> 00:27:16,760
Speaker 3: a canyon, right, there's literally fossils just strewn about on

543
00:27:17,240 --> 00:27:20,919
Speaker 3: the ground. And so it's a perfect example of like

544
00:27:21,119 --> 00:27:25,680
Speaker 3: how if you get the ideal conditions, fossils can actually

545
00:27:25,720 --> 00:27:27,639
Speaker 3: be common. This is one of the few places in

546
00:27:27,680 --> 00:27:30,359
Speaker 3: the world where the conditions were really ideal. And what

547
00:27:30,400 --> 00:27:32,280
Speaker 3: I mean by that is, first of all, it was

548
00:27:32,320 --> 00:27:35,879
Speaker 3: a place where a lot of animals and hominids, it

549
00:27:35,920 --> 00:27:39,560
Speaker 3: turns out, gathered together. And the reason is that between

550
00:27:40,119 --> 00:27:42,480
Speaker 3: you know, about one point eight million years ago and

551
00:27:42,880 --> 00:27:45,760
Speaker 3: a million or so years ago, this area was a

552
00:27:46,080 --> 00:27:48,439
Speaker 3: it was a lake. It was a shallow lake, and

553
00:27:48,480 --> 00:27:50,679
Speaker 3: so of course like a water hole, we all know

554
00:27:50,800 --> 00:27:53,680
Speaker 3: that's a good place to go to find wildlife, and

555
00:27:53,760 --> 00:27:55,920
Speaker 3: you know, hominids would have gone there for water as well,

556
00:27:56,000 --> 00:27:59,480
Speaker 3: and maybe also for hunting. It turns out, so there's

557
00:27:59,480 --> 00:28:02,960
Speaker 3: a lot of speed there and then when those individuals died.

558
00:28:03,720 --> 00:28:06,760
Speaker 3: It turns out that the second thing that is ideal

559
00:28:06,800 --> 00:28:10,720
Speaker 3: about it is that there are these volcanoes nearby, and

560
00:28:10,840 --> 00:28:15,840
Speaker 3: these volcanoes will spew out ash periodically when they erupt,

561
00:28:16,320 --> 00:28:19,760
Speaker 3: and that ash can bury all of the things in

562
00:28:19,800 --> 00:28:24,399
Speaker 3: the area, including the bodies of anything that had recently died,

563
00:28:24,880 --> 00:28:29,359
Speaker 3: and that then can basically preserve them. And basically what

564
00:28:29,440 --> 00:28:32,080
Speaker 3: happens is they go through a process in which all

565
00:28:32,119 --> 00:28:35,560
Speaker 3: of the kind of organic all the carbon based you know,

566
00:28:35,920 --> 00:28:41,640
Speaker 3: chemicals in our body get gradually converted into minerals basically

567
00:28:41,720 --> 00:28:43,360
Speaker 3: into rock, right, I mean, that's what a fossil is.

568
00:28:43,400 --> 00:28:46,840
Speaker 3: It's a rock that has the same you know, shape

569
00:28:46,920 --> 00:28:50,400
Speaker 3: as bone or other structures. And so you had the

570
00:28:50,440 --> 00:28:53,960
Speaker 3: perfect conditions for preserving all of this there. And then

571
00:28:54,040 --> 00:28:57,840
Speaker 3: the third thing, which is really remarkable is that now

572
00:28:57,920 --> 00:29:01,760
Speaker 3: you have today are a river or running through that area,

573
00:29:01,800 --> 00:29:04,480
Speaker 3: and of course that caused erosion, and then the erosion

574
00:29:04,560 --> 00:29:07,440
Speaker 3: means that the layers that have the fossils are actually

575
00:29:07,440 --> 00:29:10,160
Speaker 3: exposed at the surface. Wow, So all of those things

576
00:29:10,240 --> 00:29:12,920
Speaker 3: kind of all have to take place in order for

577
00:29:13,080 --> 00:29:16,240
Speaker 3: a fossil to not only be formed but also to

578
00:29:16,360 --> 00:29:17,440
Speaker 3: be accessible.

579
00:29:17,640 --> 00:29:20,400
Speaker 4: Why can't we develop some sort of technology that looks

580
00:29:20,440 --> 00:29:22,560
Speaker 4: into the ground to see if there's a fossil there.

581
00:29:22,760 --> 00:29:26,040
Speaker 3: Yeah, I know, I was telling a semi colleague, Manuel

582
00:29:26,080 --> 00:29:29,000
Speaker 3: Domingas RODRIGUOI every time i'm in the field with him,

583
00:29:29,080 --> 00:29:32,440
Speaker 3: I'm just so amazed by how patient he and his

584
00:29:32,480 --> 00:29:35,120
Speaker 3: team are, because they're showing us all of the ways

585
00:29:35,160 --> 00:29:38,280
Speaker 3: that they do these excavations. They're so meticulous and careful,

586
00:29:38,720 --> 00:29:45,120
Speaker 3: documenting every millimeter literally, and then they're slowly chipping away

587
00:29:45,200 --> 00:29:47,400
Speaker 3: at the edge of this canyon, and we're looking at

588
00:29:47,400 --> 00:29:50,120
Speaker 3: the canyon. I'm going like, Manuel, what's in there? Like,

589
00:29:50,160 --> 00:29:52,320
Speaker 3: don't you aren't you dying to find out what's in there?

590
00:29:52,320 --> 00:29:53,960
Speaker 3: And he's like, I mean, yeah, of course. Like I

591
00:29:53,960 --> 00:29:56,840
Speaker 3: don't know how you avoid the temptation to just kind

592
00:29:56,880 --> 00:29:58,480
Speaker 3: of hack away at it, but we know that you

593
00:29:58,560 --> 00:30:00,080
Speaker 3: have to be careful when you do thesex.

594
00:30:00,920 --> 00:30:03,000
Speaker 4: Well, actually, let's put a finer point on that, because

595
00:30:03,040 --> 00:30:06,440
Speaker 4: this is something that I see people misunderstanding online, you know,

596
00:30:06,520 --> 00:30:09,240
Speaker 4: when they're impatient about excavations all over the place. Why

597
00:30:09,280 --> 00:30:10,880
Speaker 4: do you have to be so careful? Why can't you

598
00:30:10,960 --> 00:30:13,560
Speaker 4: just take a bulldozer and find a bunch of cool fossils?

599
00:30:13,720 --> 00:30:16,320
Speaker 3: Actually, It's a really good point to discuss because you know,

600
00:30:16,320 --> 00:30:18,160
Speaker 3: there have been times in the past when that is

601
00:30:18,160 --> 00:30:21,240
Speaker 3: what people have done, and there still are certain situations

602
00:30:21,240 --> 00:30:23,720
Speaker 3: in which people still do that today. The problem is,

603
00:30:23,760 --> 00:30:26,000
Speaker 3: sure you might find well, first of all, you might

604
00:30:26,080 --> 00:30:29,160
Speaker 3: destroy the fossils in the process of excavating. That's a

605
00:30:29,200 --> 00:30:29,720
Speaker 3: real risk.

606
00:30:29,840 --> 00:30:30,040
Speaker 4: Yeah.

607
00:30:30,080 --> 00:30:32,760
Speaker 3: But the second thing is, even if you find them,

608
00:30:32,920 --> 00:30:35,080
Speaker 3: a lot of what we can learn about a fossil

609
00:30:35,320 --> 00:30:38,120
Speaker 3: comes from the exact situation in which it was found.

610
00:30:38,320 --> 00:30:40,880
Speaker 3: So you can hand me a fossil bone and I

611
00:30:40,960 --> 00:30:43,280
Speaker 3: might be able to tell you some things about it,

612
00:30:43,400 --> 00:30:45,120
Speaker 3: or more to the point, I can hand it to

613
00:30:45,480 --> 00:30:47,440
Speaker 3: Menuel and he will tell you some things about it.

614
00:30:47,480 --> 00:30:49,960
Speaker 3: But you know that we can get a lot more

615
00:30:50,000 --> 00:30:52,880
Speaker 3: information by saying, oh, yeah, but this fossil was found

616
00:30:53,200 --> 00:30:56,920
Speaker 3: together with maybe this stone tool, or with these other fossils,

617
00:30:57,000 --> 00:31:00,560
Speaker 3: or maybe there were multiple individuals together in place. That

618
00:31:00,600 --> 00:31:04,280
Speaker 3: starts to tell us something about the social interactions among

619
00:31:04,320 --> 00:31:08,760
Speaker 3: these individuals. And they've literally found carcasses of animals with

620
00:31:09,320 --> 00:31:12,160
Speaker 3: stone tool cut marks on the bones and the stone

621
00:31:12,200 --> 00:31:15,680
Speaker 3: tools are still there, like it's just it's insane, right,

622
00:31:15,720 --> 00:31:19,400
Speaker 3: So you can learn so much about what people or

623
00:31:19,600 --> 00:31:22,960
Speaker 3: hominids were doing at the time by understanding the exact

624
00:31:23,160 --> 00:31:27,120
Speaker 3: context in which these were found. So if you destroy that,

625
00:31:27,600 --> 00:31:30,520
Speaker 3: you've lost the opportunity to learn anything that we can learn.

626
00:31:30,560 --> 00:31:32,880
Speaker 4: And if you rush through your excavation, then you're sort

627
00:31:32,920 --> 00:31:35,400
Speaker 4: of using it up for future generations where people might

628
00:31:35,440 --> 00:31:40,120
Speaker 4: develop better technology, less invasive or understand there's questions that

629
00:31:40,160 --> 00:31:41,960
Speaker 4: they want to ask that we can no longer ask

630
00:31:42,040 --> 00:31:45,840
Speaker 4: because people excavated using technique X instead of technique why.

631
00:31:46,040 --> 00:31:48,480
Speaker 3: Yeah, And that's actually something that you know, archaeologists and

632
00:31:48,520 --> 00:31:52,120
Speaker 3: paleontologists today recognize and part of their sort of standard

633
00:31:52,160 --> 00:31:55,320
Speaker 3: practice is to always keep a section that is not

634
00:31:55,520 --> 00:31:58,160
Speaker 3: excavated and think that might be really interesting, but to

635
00:31:58,880 --> 00:32:02,640
Speaker 3: preserve it for future generations under the assumption, as you said,

636
00:32:02,680 --> 00:32:04,959
Speaker 3: that like at some point in the future, people are

637
00:32:05,000 --> 00:32:07,920
Speaker 3: going to have other ways of studying this that we

638
00:32:08,000 --> 00:32:10,400
Speaker 3: don't have today, and we don't want to, you know,

639
00:32:10,680 --> 00:32:12,600
Speaker 3: cause them to miss out on that opportunity.

640
00:32:12,960 --> 00:32:15,320
Speaker 4: So why can't we like put a thumper on the

641
00:32:15,360 --> 00:32:18,080
Speaker 4: surface and like gatherunce your data and feed it into

642
00:32:18,120 --> 00:32:19,760
Speaker 4: AI and have it tell us like here are all

643
00:32:19,760 --> 00:32:20,320
Speaker 4: the fossils.

644
00:32:20,680 --> 00:32:23,240
Speaker 3: Yeah, So I think there have been some developments along

645
00:32:23,240 --> 00:32:26,000
Speaker 3: those lines. They can use things like ground penetrating radar

646
00:32:26,120 --> 00:32:28,440
Speaker 3: to like look underground and try to get some sense

647
00:32:28,720 --> 00:32:30,320
Speaker 3: of what's there, and you might be able to find

648
00:32:30,440 --> 00:32:33,560
Speaker 3: some large things that way, but to find you know,

649
00:32:33,600 --> 00:32:35,840
Speaker 3: some of the fossils that they pull out of these

650
00:32:35,880 --> 00:32:39,720
Speaker 3: sites are incredibly tiny, and so, you know, I think

651
00:32:39,760 --> 00:32:43,640
Speaker 3: part of it is is just the resolution of these technologies.

652
00:32:43,920 --> 00:32:45,440
Speaker 3: And the other thing I think is that you know,

653
00:32:45,640 --> 00:32:48,200
Speaker 3: keep in mind, the fossil is rock, yeah, and you're

654
00:32:48,240 --> 00:32:51,800
Speaker 3: looking for one rock embedded within a bunch of other rocks. So, like,

655
00:32:52,320 --> 00:32:54,320
Speaker 3: you know, I don't know much about the specifics of

656
00:32:54,320 --> 00:32:56,520
Speaker 3: how the technology works, but I'm guessing that just being

657
00:32:56,560 --> 00:32:59,600
Speaker 3: able to differentiate between those two types of things is

658
00:32:59,640 --> 00:33:00,480
Speaker 3: probably really hard.

659
00:33:00,560 --> 00:33:02,600
Speaker 4: Yeah, you're looking for a needle in a needlestack.

660
00:33:02,760 --> 00:33:03,240
Speaker 3: Basically.

661
00:33:03,480 --> 00:33:05,960
Speaker 1: How many hamidid species has manuel found in there?

662
00:33:06,560 --> 00:33:08,400
Speaker 3: Well, they have found a few, but you know, in

663
00:33:08,480 --> 00:33:11,560
Speaker 3: old of I Gorge generally there are three species that

664
00:33:11,600 --> 00:33:14,720
Speaker 3: are known from the fossil record from that particular site,

665
00:33:14,720 --> 00:33:17,000
Speaker 3: and it's actually the place where two of them were

666
00:33:17,000 --> 00:33:20,600
Speaker 3: first discovered. So the very first hominid fossil found at

667
00:33:20,600 --> 00:33:24,360
Speaker 3: old of I Gorge was found by Mary Leaky along

668
00:33:24,400 --> 00:33:26,680
Speaker 3: with her her husband Lewis Leaky. They were sort of

669
00:33:26,680 --> 00:33:30,600
Speaker 3: the pioneers of looking for human hominid fossils in that site,

670
00:33:30,880 --> 00:33:34,520
Speaker 3: and they found one that they called zinge z i

671
00:33:34,720 --> 00:33:39,600
Speaker 3: in j was the nickname. It was short for Zinganthropists

672
00:33:39,760 --> 00:33:42,920
Speaker 3: boisei as the species, and the genus name has been

673
00:33:43,000 --> 00:33:47,240
Speaker 3: revised since those days. It's now known as Paranthropist Boisey.

674
00:33:47,400 --> 00:33:49,280
Speaker 3: But that was a really big deal, and that's a

675
00:33:49,320 --> 00:33:51,920
Speaker 3: good example of a hominid that we think was on

676
00:33:52,040 --> 00:33:55,920
Speaker 3: a branch that didn't eventually lead to us. There's you know,

677
00:33:56,040 --> 00:33:58,720
Speaker 3: like I said, there's debate among folks in this field

678
00:33:58,760 --> 00:34:02,120
Speaker 3: about exactly what the the shape of that family tree

679
00:34:02,480 --> 00:34:05,120
Speaker 3: looked like and which species led to which other species,

680
00:34:05,120 --> 00:34:07,320
Speaker 3: et cetera. But they are pretty different from us. They

681
00:34:07,360 --> 00:34:10,080
Speaker 3: were more sort of like large bodied, very thick jaw.

682
00:34:10,200 --> 00:34:14,759
Speaker 3: They looked like they were eating like grasses or other

683
00:34:14,960 --> 00:34:17,960
Speaker 3: very like fibrous foods that are really hard to break down.

684
00:34:18,040 --> 00:34:21,239
Speaker 3: So their skull is quite different from the species that

685
00:34:22,200 --> 00:34:24,440
Speaker 3: we think are the ones that eventually led to us.

686
00:34:25,120 --> 00:34:29,000
Speaker 3: Another species that was first found in OLDEVII Gorge is

687
00:34:29,160 --> 00:34:33,600
Speaker 3: Homo habilis, so this is now in the genus Homo, right,

688
00:34:34,080 --> 00:34:37,000
Speaker 3: and so this is something that is certainly more close

689
00:34:37,120 --> 00:34:40,160
Speaker 3: to Homo sapiens, but still still pretty distinct from us.

690
00:34:40,200 --> 00:34:42,000
Speaker 3: And in part it's based on like the size of

691
00:34:42,080 --> 00:34:44,600
Speaker 3: the head, which of course is you know, an indication

692
00:34:44,680 --> 00:34:46,839
Speaker 3: of the size of the brain. So we talked before

693
00:34:46,840 --> 00:34:49,759
Speaker 3: about like walking upright being one of the big transitions

694
00:34:49,800 --> 00:34:52,200
Speaker 3: that took place. The other major one, I mean, there

695
00:34:52,200 --> 00:34:54,120
Speaker 3: were a lot that the other major one was the

696
00:34:54,760 --> 00:34:58,600
Speaker 3: expansion of the brain and therefore the expansion of the skull.

697
00:34:59,080 --> 00:35:02,960
Speaker 3: And so in part our genus Homo is defined by

698
00:35:03,239 --> 00:35:06,040
Speaker 3: the size of the skull, but we also see within

699
00:35:06,280 --> 00:35:09,800
Speaker 3: species of Homo kind of more and more expansion of

700
00:35:10,120 --> 00:35:14,759
Speaker 3: the brain, which you know, is at least correlated with intelligence.

701
00:35:14,800 --> 00:35:18,880
Speaker 3: Intelligence is famously hard to hard to define, hard to measure.

702
00:35:18,960 --> 00:35:21,760
Speaker 3: It's not, you know, brain size is a perfect measurement

703
00:35:21,800 --> 00:35:24,719
Speaker 3: of intelligence by any means. But at least in looking

704
00:35:24,800 --> 00:35:26,840
Speaker 3: at the history of human evolution, we do think that

705
00:35:27,360 --> 00:35:30,359
Speaker 3: with a larger brain, you know, generally speaking, you start

706
00:35:30,440 --> 00:35:34,200
Speaker 3: to see more intelligence and more sophisticated types of behaviors.

707
00:35:34,719 --> 00:35:37,120
Speaker 4: It is amazing that we have any fossils, given how

708
00:35:37,239 --> 00:35:39,640
Speaker 4: hard it is to arrange all of those things to

709
00:35:39,760 --> 00:35:43,120
Speaker 4: happen just the right way. Don't you worry that you're

710
00:35:43,160 --> 00:35:47,960
Speaker 4: looking at an unusual, unrepresentative sample of the ancient population

711
00:35:48,440 --> 00:35:51,600
Speaker 4: because you know that it doesn't happen evenly everywhere. For example,

712
00:35:51,680 --> 00:35:55,040
Speaker 4: if future humans only studied like current physics professors, I

713
00:35:55,080 --> 00:35:58,160
Speaker 4: wouldn't want them to extrapolate, you know, the whole population

714
00:35:58,480 --> 00:36:00,920
Speaker 4: based on a few of us. Don't you worry about that?

715
00:36:01,040 --> 00:36:02,880
Speaker 4: And how big a sample are we talking about? Like

716
00:36:02,960 --> 00:36:05,440
Speaker 4: how many different individuals have we found fossils of?

717
00:36:05,840 --> 00:36:07,480
Speaker 3: Yeah, that's a really good point. So you've got the

718
00:36:07,520 --> 00:36:11,080
Speaker 3: small sample size problem. Anytime you're dealing with fossils, right,

719
00:36:11,120 --> 00:36:13,920
Speaker 3: you're gonna, like I said, it's so hard to you know,

720
00:36:14,320 --> 00:36:17,360
Speaker 3: even have them be preserved, much less find them. So

721
00:36:17,520 --> 00:36:20,120
Speaker 3: what often happens is, you know, somebody finds something and

722
00:36:20,200 --> 00:36:23,239
Speaker 3: it's the first of that kind, right, and then that

723
00:36:23,360 --> 00:36:26,840
Speaker 3: makes it hard to draw too many conclusions because we

724
00:36:26,920 --> 00:36:30,080
Speaker 3: don't know, you know, how representative it was. But what

725
00:36:30,280 --> 00:36:33,719
Speaker 3: has fortunately happened in the last I would say, you know,

726
00:36:33,800 --> 00:36:35,879
Speaker 3: sort of fifty years or so, especially in the last

727
00:36:35,920 --> 00:36:39,480
Speaker 3: few decades, is we've found more and more examples of

728
00:36:39,680 --> 00:36:43,960
Speaker 3: the same what people generally accept as being the same species,

729
00:36:44,040 --> 00:36:45,759
Speaker 3: And like I said, there's some debate about it. Is

730
00:36:45,840 --> 00:36:48,040
Speaker 3: this the same? Is this not where to draw the line.

731
00:36:48,120 --> 00:36:50,880
Speaker 3: But there's some exceptions, some of the earliest species that

732
00:36:50,920 --> 00:36:53,920
Speaker 3: are only known from a few specimens. But as you

733
00:36:54,040 --> 00:36:56,200
Speaker 3: get more and more recent, as you get to something like,

734
00:36:56,280 --> 00:37:00,880
Speaker 3: for example, homoerectus. That's a really interesting species because we

735
00:37:01,080 --> 00:37:04,200
Speaker 3: know that the earliest Homo Erectus were found in Africa,

736
00:37:04,600 --> 00:37:08,080
Speaker 3: but then you start to see Homo Erectus popping up

737
00:37:08,280 --> 00:37:11,600
Speaker 3: in the Middle East, in parts of Europe, and in

738
00:37:11,719 --> 00:37:14,200
Speaker 3: parts of Asia and Southeast Asia. In fact, the first

739
00:37:14,280 --> 00:37:16,480
Speaker 3: one was found on the island of Java in what

740
00:37:16,640 --> 00:37:19,680
Speaker 3: is today Indonesia. So that was the very first member

741
00:37:19,760 --> 00:37:22,720
Speaker 3: of our lineage, the very first hominid to leave Africa

742
00:37:22,920 --> 00:37:25,880
Speaker 3: and spread out across a lot of the world. So

743
00:37:25,920 --> 00:37:28,680
Speaker 3: there's a lot now of fossils of homoerectus.

744
00:37:29,000 --> 00:37:30,880
Speaker 4: Is that like one hundred or a thousand? A million?

745
00:37:30,920 --> 00:37:31,879
Speaker 4: How many are we talking about?

746
00:37:31,960 --> 00:37:36,200
Speaker 3: Not a million? I don't know the exact count, but

747
00:37:36,280 --> 00:37:39,440
Speaker 3: I would hazard a guess that we're talking about you know,

748
00:37:39,680 --> 00:37:42,640
Speaker 3: hundreds something like that. Yeah, And you know, some of

749
00:37:42,680 --> 00:37:45,600
Speaker 3: these are very fragmentary, so you might only have one bone, right,

750
00:37:45,719 --> 00:37:47,800
Speaker 3: and in other cases you have part of a skull,

751
00:37:48,280 --> 00:37:51,080
Speaker 3: but kind of putting it all together, we have a

752
00:37:51,320 --> 00:37:54,400
Speaker 3: very good sense of what the entire body looked like.

753
00:37:54,480 --> 00:37:56,239
Speaker 3: That's the other thing, right, is like you might only

754
00:37:56,360 --> 00:37:59,080
Speaker 3: have a tiny piece of something, and you have to

755
00:37:59,120 --> 00:38:01,239
Speaker 3: figure out how much information can you get about the

756
00:38:01,520 --> 00:38:05,279
Speaker 3: entire individual, much less the entire species from that one

757
00:38:05,360 --> 00:38:08,000
Speaker 3: little fragment. In some cases we can learn a lot,

758
00:38:08,160 --> 00:38:10,480
Speaker 3: but you know, it certainly helps to have more and

759
00:38:10,680 --> 00:38:12,400
Speaker 3: more pieces of that puzzle.

760
00:38:12,560 --> 00:38:14,520
Speaker 1: Can we talk about timeframe a little? So I think

761
00:38:14,520 --> 00:38:17,200
Speaker 1: you said that the split between chimpanzees and humans was

762
00:38:17,320 --> 00:38:20,440
Speaker 1: like six to seven million years ago, and then you

763
00:38:20,520 --> 00:38:23,840
Speaker 1: were talking about Manuel study site, and I never remember

764
00:38:23,840 --> 00:38:24,880
Speaker 1: the name of the place, so I'm just going to

765
00:38:24,920 --> 00:38:28,000
Speaker 1: say Manuel Study site that was one million to one

766
00:38:28,000 --> 00:38:29,200
Speaker 1: point eight million years ago.

767
00:38:29,520 --> 00:38:30,239
Speaker 2: What is the like.

768
00:38:31,719 --> 00:38:34,960
Speaker 1: Earliest date when there were other hominids around? And this

769
00:38:35,080 --> 00:38:36,480
Speaker 1: question is going to lead into whether or not we

770
00:38:36,520 --> 00:38:37,680
Speaker 1: can get DNA out of any.

771
00:38:37,560 --> 00:38:41,080
Speaker 3: Of these Yeah, yeah, that's really important questions. So yeah,

772
00:38:41,160 --> 00:38:44,600
Speaker 3: so yeah, you know, you start to see, let's see,

773
00:38:44,760 --> 00:38:49,200
Speaker 3: I think Lucy's species that's Astralopithecus e forensis is around

774
00:38:49,280 --> 00:38:51,759
Speaker 3: three and a half million years ago. So there you

775
00:38:51,920 --> 00:38:55,360
Speaker 3: have an example of a species that is definitely walking

776
00:38:55,520 --> 00:38:58,080
Speaker 3: upright on two feet, very much like us. We even

777
00:38:58,520 --> 00:39:01,320
Speaker 3: have footprints. This is a credible there's a site in

778
00:39:01,440 --> 00:39:06,960
Speaker 3: Tanzania near Oldevi Gorge where there are preserved footprints where yeah,

779
00:39:07,120 --> 00:39:09,920
Speaker 3: I mean it really is like basically like perfect conditions.

780
00:39:09,920 --> 00:39:13,360
Speaker 3: The volcano, one of those volcanoes erupted, there was ash

781
00:39:13,600 --> 00:39:15,880
Speaker 3: all over the ground and then it rained, so then

782
00:39:15,920 --> 00:39:19,000
Speaker 3: you have like a wet cement situation, and then some

783
00:39:19,200 --> 00:39:23,600
Speaker 3: of these individuals walked through that area and the ash

784
00:39:23,719 --> 00:39:27,080
Speaker 3: hardened and then that was preserved, so we could actually

785
00:39:27,280 --> 00:39:30,120
Speaker 3: retrace their exact gate. You know, the kind of like

786
00:39:30,160 --> 00:39:32,440
Speaker 3: if you go to get fitted for like running shoes

787
00:39:32,560 --> 00:39:34,719
Speaker 3: or something, they'll go and they'll like analyze your gait,

788
00:39:34,840 --> 00:39:37,560
Speaker 3: like how long are your strides, where are you kind

789
00:39:37,560 --> 00:39:39,719
Speaker 3: of putting pressure on your foot, and they'll give you

790
00:39:39,800 --> 00:39:43,080
Speaker 3: the right shoe to kind of help with your specific gate.

791
00:39:43,280 --> 00:39:46,279
Speaker 3: They can do those types of reconstructions on the gate

792
00:39:46,400 --> 00:39:49,680
Speaker 3: of Astralopithecus eforensus at three and a half million years ago.

793
00:39:50,160 --> 00:39:52,080
Speaker 3: Because of these tracks.

794
00:39:51,800 --> 00:39:54,120
Speaker 4: Incredible, so cool can they tell if they had to

795
00:39:54,200 --> 00:39:56,040
Speaker 4: like drag a screaming toddler along or something.

796
00:39:56,239 --> 00:40:01,359
Speaker 3: Well, actually, so there is a prehistoric There is an

797
00:40:01,400 --> 00:40:05,640
Speaker 3: indication of older individuals and younger individuals in some cases,

798
00:40:06,040 --> 00:40:09,320
Speaker 3: and we have now also found fossils of individuals of

799
00:40:09,400 --> 00:40:11,560
Speaker 3: different ages for some of these species. So we're starting

800
00:40:11,600 --> 00:40:13,560
Speaker 3: to fill in a little bit of what the kind

801
00:40:13,640 --> 00:40:15,360
Speaker 3: of you know, what does a childhood look like for

802
00:40:15,440 --> 00:40:18,359
Speaker 3: homoerectus and things like that. But you know, the other

803
00:40:18,400 --> 00:40:20,360
Speaker 3: thing I was going to say is so for that species,

804
00:40:20,440 --> 00:40:23,560
Speaker 3: for Lucy's species, as Trollopithecus e forensis they were walking

805
00:40:23,640 --> 00:40:25,560
Speaker 3: upright like us, but they didn't have a big brain

806
00:40:25,680 --> 00:40:28,000
Speaker 3: like us yet. So we're starting to sort of see

807
00:40:28,080 --> 00:40:30,880
Speaker 3: pieces that we know walking upright happened first. So by

808
00:40:30,920 --> 00:40:32,680
Speaker 3: three and a half million years ago, you had people

809
00:40:32,760 --> 00:40:35,320
Speaker 3: walking around in much the same way that we walk around,

810
00:40:35,640 --> 00:40:38,719
Speaker 3: but they didn't have a brain nearly the size of ours.

811
00:40:38,760 --> 00:40:40,680
Speaker 3: It was more of a chimpanzee sized brain. So we

812
00:40:40,800 --> 00:40:47,000
Speaker 3: assume that means most aspects of complex human behavior, language, art, social,

813
00:40:47,320 --> 00:40:50,520
Speaker 3: you know, dynamics wouldn't have yet been in place. Now

814
00:40:50,560 --> 00:40:53,400
Speaker 3: there's a lot of you know, guesswork that has to

815
00:40:53,480 --> 00:40:57,080
Speaker 3: be done, but that's that's the best guess for that,

816
00:40:57,320 --> 00:41:01,400
Speaker 3: So you don't get the you know, the very enlarged

817
00:41:01,560 --> 00:41:06,160
Speaker 3: brain happening until just the last couple of million years,

818
00:41:06,640 --> 00:41:10,240
Speaker 3: and it's it keeps increasing over the last two million years.

819
00:41:10,320 --> 00:41:13,040
Speaker 3: And this is super interesting because you also want to know, well,

820
00:41:13,120 --> 00:41:18,759
Speaker 3: why why did we become more intelligent at this particular time, right,

821
00:41:19,640 --> 00:41:22,440
Speaker 3: And one of the things that is fascinating is that

822
00:41:22,760 --> 00:41:25,400
Speaker 3: the time at which our brain started to really shoot

823
00:41:25,480 --> 00:41:28,680
Speaker 3: up in size coincides with the time in which the

824
00:41:28,840 --> 00:41:33,719
Speaker 3: climate in East Africa was very volatile, like it was,

825
00:41:34,000 --> 00:41:37,040
Speaker 3: you know, swinging wildly from you know, hot and wet

826
00:41:37,239 --> 00:41:40,320
Speaker 3: to cold and dry, and it kept changing in a

827
00:41:40,440 --> 00:41:44,399
Speaker 3: much faster way than it had previously. And so there's

828
00:41:44,480 --> 00:41:49,120
Speaker 3: this idea that those wild fluctuations in climate led to uncertainty, right,

829
00:41:49,360 --> 00:41:53,160
Speaker 3: and you had to kind of keep adapting, adjusting, but

830
00:41:53,280 --> 00:41:56,520
Speaker 3: maybe in a way that evolution itself can't keep up with, right,

831
00:41:56,640 --> 00:41:59,480
Speaker 3: So you can't adapt through natural selection when the environment

832
00:41:59,800 --> 00:42:04,120
Speaker 3: is constantly changing. Rather, maybe a better way to do

833
00:42:04,200 --> 00:42:08,239
Speaker 3: it is to develop intelligence that allows you to be

834
00:42:08,600 --> 00:42:11,480
Speaker 3: more adaptable yourself, to be able to use your intelligence

835
00:42:11,520 --> 00:42:16,080
Speaker 3: to work together as a cooperative society to try to

836
00:42:16,160 --> 00:42:19,960
Speaker 3: solve problems like finding food, finding water, protecting yourself from enemies.

837
00:42:20,239 --> 00:42:24,080
Speaker 3: So there's this idea that that climate being of going

838
00:42:24,120 --> 00:42:28,440
Speaker 3: through these wild changes might have driven the intelligence of

839
00:42:28,719 --> 00:42:29,480
Speaker 3: our ancestors.

840
00:42:29,800 --> 00:42:32,000
Speaker 1: So that leads nicely into a question we have from

841
00:42:32,200 --> 00:42:35,120
Speaker 1: listener Jesse. And so here's the question, if there is

842
00:42:35,160 --> 00:42:39,200
Speaker 1: a physical and or sociological advantage to becoming an upright

843
00:42:39,360 --> 00:42:43,160
Speaker 1: tool using intelligent species, would the same advantages apply to

844
00:42:43,200 --> 00:42:46,840
Speaker 1: the rise of an intelligent alien species on another habitable planet.

845
00:42:47,280 --> 00:42:50,840
Speaker 1: And if physical characteristics are essential for becoming an intelligent species,

846
00:42:51,440 --> 00:42:55,000
Speaker 1: must they then be more human? Like surely we could

847
00:42:55,000 --> 00:42:57,920
Speaker 1: have limbs grown out of our heads or otherwise. Okay,

848
00:42:57,960 --> 00:42:59,800
Speaker 1: So I feel like that kind of ties into what

849
00:43:00,280 --> 00:43:03,000
Speaker 1: is needed to become an intelligent species. And this is

850
00:43:03,000 --> 00:43:05,320
Speaker 1: also a question for Daniel, who thinks a lot about aliens.

851
00:43:06,840 --> 00:43:08,480
Speaker 3: Well, you know, I love this question for a lot

852
00:43:08,520 --> 00:43:10,560
Speaker 3: of reasons, one of which is I'm teaching a class

853
00:43:10,719 --> 00:43:14,879
Speaker 3: right now on astrobiology and we're asking exactly these kinds

854
00:43:14,880 --> 00:43:17,160
Speaker 3: of questions and talking about them with our students, like

855
00:43:17,239 --> 00:43:19,959
Speaker 3: how how much can we use the history of life

856
00:43:20,000 --> 00:43:23,840
Speaker 3: on Earth, to think about what might have already happened

857
00:43:23,880 --> 00:43:25,799
Speaker 3: on other planets, and to think about what could happen

858
00:43:25,880 --> 00:43:28,400
Speaker 3: in the future on other planets and other worlds and

859
00:43:28,440 --> 00:43:31,480
Speaker 3: different lineages of life. And so, you know, I think

860
00:43:32,440 --> 00:43:36,719
Speaker 3: there is this idea at least that some species on

861
00:43:36,920 --> 00:43:40,680
Speaker 3: Earth would have become as intelligent as we are. That's

862
00:43:40,800 --> 00:43:43,120
Speaker 3: one way of thinking about it that like, it happened

863
00:43:43,160 --> 00:43:46,279
Speaker 3: to be us because you know, the asteroid hit the

864
00:43:46,360 --> 00:43:49,440
Speaker 3: Earth and killed the dinosaurs and it ended up being mammals,

865
00:43:49,520 --> 00:43:51,960
Speaker 3: But maybe we could have had a super intelligent dinosaur

866
00:43:52,120 --> 00:43:55,480
Speaker 3: slash bird or something like that. That's like one argument

867
00:43:55,600 --> 00:43:57,520
Speaker 3: that has been made that like somebody was going to

868
00:43:57,520 --> 00:44:00,960
Speaker 3: become super smart and it happened to be us. There's

869
00:44:00,960 --> 00:44:04,319
Speaker 3: another argument that, like, it doesn't have to happen at all,

870
00:44:04,880 --> 00:44:07,920
Speaker 3: and the conditions had to really just be just right.

871
00:44:08,120 --> 00:44:10,680
Speaker 3: And in that way of thinking about it, you know,

872
00:44:10,840 --> 00:44:12,719
Speaker 3: we happen to be at the right place at the

873
00:44:12,840 --> 00:44:18,279
Speaker 3: right time and have the right kind of combination of

874
00:44:18,440 --> 00:44:22,520
Speaker 3: traits already in existence that allowed us to sort of

875
00:44:22,960 --> 00:44:27,200
Speaker 3: evolve through natural selection to be able to you know,

876
00:44:27,719 --> 00:44:30,640
Speaker 3: basically solve problems in one particular way, and that way

877
00:44:30,960 --> 00:44:34,360
Speaker 3: appears to have been through the use of language and

878
00:44:34,480 --> 00:44:39,319
Speaker 3: collective problem solving and social you know, complex social interactions

879
00:44:39,400 --> 00:44:41,360
Speaker 3: that we know how to manage. And that's kind of

880
00:44:41,400 --> 00:44:44,960
Speaker 3: a uniquely human way of solving the problems of of

881
00:44:45,280 --> 00:44:48,239
Speaker 3: you know, adjusting to this extreme environment. So, you know,

882
00:44:48,520 --> 00:44:51,279
Speaker 3: I tend to kind of lean more that way that

883
00:44:51,520 --> 00:44:54,000
Speaker 3: like we got lucky, you know, like it didn't have

884
00:44:54,160 --> 00:44:58,040
Speaker 3: to happen this way. And while you know that has

885
00:44:58,080 --> 00:45:00,799
Speaker 3: implications for understanding our origin, and I also do think

886
00:45:00,840 --> 00:45:04,359
Speaker 3: it has implications for thinking about what could happen elsewhere. Right,

887
00:45:04,560 --> 00:45:08,800
Speaker 3: So it doesn't necessarily mean that there has to be

888
00:45:09,360 --> 00:45:13,279
Speaker 3: intelligent life elsewhere, but maybe if the conditions are just right,

889
00:45:13,400 --> 00:45:17,279
Speaker 3: and there are species elsewhere that happen to have the

890
00:45:17,560 --> 00:45:20,719
Speaker 3: conditions that are necessary and be at the right place

891
00:45:20,760 --> 00:45:22,640
Speaker 3: in the right time, then that that might happen for

892
00:45:22,719 --> 00:45:23,000
Speaker 3: them too.

893
00:45:23,680 --> 00:45:25,400
Speaker 4: I think it's really important to try to tell these

894
00:45:25,400 --> 00:45:28,360
Speaker 4: stories and try to understand our history. But something I

895
00:45:28,440 --> 00:45:31,840
Speaker 4: struggle with is knowing how to test these ideas, Like

896
00:45:31,960 --> 00:45:34,560
Speaker 4: it sounds compelling, but you know, there could be another

897
00:45:34,640 --> 00:45:37,880
Speaker 4: idea that explains that there could be another factor. Usually

898
00:45:37,960 --> 00:45:40,120
Speaker 4: in science, you don't just tell a compelling story that

899
00:45:40,200 --> 00:45:42,480
Speaker 4: describes you, dit you try to predict something that happens

900
00:45:42,560 --> 00:45:44,840
Speaker 4: and say, well, here's a prediction I can use to

901
00:45:44,920 --> 00:45:48,160
Speaker 4: test this theory versus that theory are aliens. The way

902
00:45:48,200 --> 00:45:50,040
Speaker 4: we can do that you build a model for how

903
00:45:50,080 --> 00:45:51,880
Speaker 4: intelligence develops, and then you can apply it to some

904
00:45:52,000 --> 00:45:54,800
Speaker 4: new data sete. You're like, I predict intelligence on this planet,

905
00:45:54,880 --> 00:45:57,320
Speaker 4: or I predict no intelligence on this planet, or is

906
00:45:57,360 --> 00:46:00,279
Speaker 4: this just an impossible standard because we're talking about in

907
00:46:00,320 --> 00:46:02,360
Speaker 4: the deep past and things that move very slowly.

908
00:46:02,840 --> 00:46:04,879
Speaker 3: Yeah. No, I think it's a really good, really good point,

909
00:46:04,960 --> 00:46:06,839
Speaker 3: And you're right that we always want to be able

910
00:46:06,920 --> 00:46:10,440
Speaker 3: to back up our assertions with data and so otherwise

911
00:46:10,480 --> 00:46:13,520
Speaker 3: it's a nice story, but you know, there's no way

912
00:46:13,600 --> 00:46:16,239
Speaker 3: to know that that's the correct interpretation. So one of

913
00:46:16,280 --> 00:46:18,280
Speaker 3: the problems we have with the study of human evolution

914
00:46:18,760 --> 00:46:21,080
Speaker 3: is that, as far as we know, it only happened once.

915
00:46:21,280 --> 00:46:24,120
Speaker 3: And so you know, even if we could reconstruct the

916
00:46:24,239 --> 00:46:28,360
Speaker 3: exact sequence of events that led to us, it still

917
00:46:28,480 --> 00:46:31,880
Speaker 3: doesn't tell us how generalizable that is. It still doesn't

918
00:46:31,920 --> 00:46:33,799
Speaker 3: tell us how likely it was to We can say

919
00:46:33,800 --> 00:46:37,160
Speaker 3: that it did happen, but we can't necessarily know well,

920
00:46:37,280 --> 00:46:39,279
Speaker 3: if you change X, Y and Z, would it have

921
00:46:39,400 --> 00:46:42,040
Speaker 3: played out that same way again? So I mean there

922
00:46:42,080 --> 00:46:44,880
Speaker 3: are ways to do simulations, right, There are ways to

923
00:46:45,080 --> 00:46:49,760
Speaker 3: run experiments with other organisms, you know, that aren't humans,

924
00:46:49,800 --> 00:46:52,359
Speaker 3: that we can try to recreate certain conditions, but it's

925
00:46:52,400 --> 00:46:54,440
Speaker 3: not quite the same. So I think part of this

926
00:46:54,800 --> 00:46:58,239
Speaker 3: is the inherent problem we have of you know, human

927
00:46:58,280 --> 00:47:02,800
Speaker 3: evolution happened once. There's only one lineage of hominids, although

928
00:47:03,280 --> 00:47:06,240
Speaker 3: if there were multiple species living in the same place,

929
00:47:06,719 --> 00:47:09,200
Speaker 3: that does allow us to ask some questions about the

930
00:47:09,239 --> 00:47:13,440
Speaker 3: differences that existed between them, and you know, maybe someday

931
00:47:13,480 --> 00:47:16,400
Speaker 3: we'll know why our lineage is the one that survived

932
00:47:16,480 --> 00:47:19,200
Speaker 3: and not any of the others that very well could have.

933
00:47:19,560 --> 00:47:21,359
Speaker 1: All right, let's take a break, and when we get back,

934
00:47:21,400 --> 00:47:24,120
Speaker 1: we'll take a question from Alberto about whether or not

935
00:47:24,520 --> 00:47:28,200
Speaker 1: our hominid species has let's say, mixed our genetic information

936
00:47:28,400 --> 00:47:31,080
Speaker 1: with some of the other hominid species in our early history.

937
00:47:50,880 --> 00:47:53,760
Speaker 1: And we're back, and let's start with a question from Alberto.

938
00:47:53,840 --> 00:47:57,239
Speaker 1: All right, So Alberto asked, I recently learned about another

939
00:47:57,280 --> 00:48:00,680
Speaker 1: hominin branch called Demnis evans. Would you be willing to

940
00:48:00,760 --> 00:48:03,560
Speaker 1: share more information about them. Are there modern humans that

941
00:48:03,680 --> 00:48:06,719
Speaker 1: share their DNA? And I'll add I think Neanderthals we

942
00:48:06,760 --> 00:48:09,480
Speaker 1: also share some DNA with them, So yeah, tell us

943
00:48:09,520 --> 00:48:12,360
Speaker 1: about our species doing the hanky panky with some others.

944
00:48:12,760 --> 00:48:14,880
Speaker 3: Yeah, I mean, this is one example of some of

945
00:48:15,000 --> 00:48:17,360
Speaker 3: the just absolutely incredible work that has happened in the

946
00:48:17,440 --> 00:48:19,759
Speaker 3: last few decades that's really kind of given us a

947
00:48:19,880 --> 00:48:24,120
Speaker 3: much much more complete picture of our ancestors and how

948
00:48:24,160 --> 00:48:27,239
Speaker 3: we got here, but also like a much much more

949
00:48:27,600 --> 00:48:31,080
Speaker 3: i would say, interesting, a much more complex version of

950
00:48:31,160 --> 00:48:34,040
Speaker 3: the story. So yeah, So what happened with the Denis Evans.

951
00:48:34,120 --> 00:48:36,480
Speaker 3: This is a discovery that took place in two thousand

952
00:48:36,520 --> 00:48:39,560
Speaker 3: and eight in a cave called Denis of a cave

953
00:48:39,719 --> 00:48:43,480
Speaker 3: in the Altai Mountains of Siberia, And what was found

954
00:48:43,840 --> 00:48:47,080
Speaker 3: was a part of a finger and a tooth, so

955
00:48:47,280 --> 00:48:50,680
Speaker 3: not much, not much to go by, but because this

956
00:48:50,960 --> 00:48:54,960
Speaker 3: cave is a place that is pretty cold and dry,

957
00:48:55,160 --> 00:48:57,720
Speaker 3: that turns out to be pretty good for preserving DNA,

958
00:48:58,360 --> 00:49:00,840
Speaker 3: And in this case they were able to to actually

959
00:49:01,400 --> 00:49:06,000
Speaker 3: extract and sequence the entire genome of the individual that

960
00:49:06,160 --> 00:49:09,600
Speaker 3: was found, just based on this tiny little fragment of

961
00:49:09,760 --> 00:49:10,479
Speaker 3: bone and teeth.

962
00:49:10,640 --> 00:49:12,680
Speaker 4: So this is bone and teeth, not fossils, just to

963
00:49:12,719 --> 00:49:13,080
Speaker 4: be clear.

964
00:49:13,400 --> 00:49:15,959
Speaker 3: So it was in a state that was I guess

965
00:49:16,120 --> 00:49:20,879
Speaker 3: partially fossilized, and so there was still organic material in there,

966
00:49:21,040 --> 00:49:24,560
Speaker 3: and so they were able to actually get enough of it.

967
00:49:25,000 --> 00:49:27,000
Speaker 3: And you know, part of what happens with looking at

968
00:49:27,040 --> 00:49:29,640
Speaker 3: ancient DNA is you can still have some DNA present,

969
00:49:29,760 --> 00:49:32,520
Speaker 3: but if it's broken up enough, if it's degraded enough,

970
00:49:32,800 --> 00:49:35,080
Speaker 3: then you can't necessarily make much sense out of it.

971
00:49:35,200 --> 00:49:38,960
Speaker 3: So this was both preserved and intact enough for them

972
00:49:39,040 --> 00:49:43,400
Speaker 3: to actually sequence the entire genome that was published in

973
00:49:43,480 --> 00:49:47,800
Speaker 3: twenty ten, and basically what they determined is that this

974
00:49:48,000 --> 00:49:52,480
Speaker 3: is a new type of hominid and they were similar

975
00:49:52,640 --> 00:49:57,320
Speaker 3: to Neanderthals because we also have DNA in fact complete

976
00:49:57,400 --> 00:50:01,320
Speaker 3: genomes from Neanderthals that had already been published, and so

977
00:50:01,480 --> 00:50:05,640
Speaker 3: this is basically a branch of our family tree that

978
00:50:05,920 --> 00:50:09,879
Speaker 3: is similar to Neanderthals and yet distinct enough that they're

979
00:50:09,960 --> 00:50:14,360
Speaker 3: kind of considered a separate, separate type of hominid. And

980
00:50:14,440 --> 00:50:17,800
Speaker 3: I'm not using the term species because there's debates about

981
00:50:18,000 --> 00:50:20,800
Speaker 3: is it actually different species, is it, you know, the

982
00:50:20,840 --> 00:50:24,200
Speaker 3: same species as us what we do know is by

983
00:50:24,280 --> 00:50:28,440
Speaker 3: looking at the DNA of these Denisovans, is that we

984
00:50:28,640 --> 00:50:33,160
Speaker 3: actually still have some of the DNA from Denisovans in

985
00:50:33,320 --> 00:50:37,520
Speaker 3: people living today. And so, yes, we know that our ancestors,

986
00:50:37,520 --> 00:50:41,719
Speaker 3: I say us as Homo sapiens modern humans, that at

987
00:50:41,760 --> 00:50:44,120
Speaker 3: some point in the past, and actually we now know

988
00:50:44,239 --> 00:50:48,040
Speaker 3: this happened multiple times in the past, that there were

989
00:50:48,120 --> 00:50:52,120
Speaker 3: episodes in which our ancestors, Homo sapiens, made it and

990
00:50:52,239 --> 00:50:56,239
Speaker 3: had children with Denisovans. And not only that, but that

991
00:50:56,800 --> 00:51:00,880
Speaker 3: that led to a child and that child was you know,

992
00:51:01,120 --> 00:51:05,440
Speaker 3: cared for and nurtured and survived itself to be an

993
00:51:05,480 --> 00:51:07,200
Speaker 3: adult and to go on and have its own kids.

994
00:51:07,239 --> 00:51:09,560
Speaker 3: So I think it's useful to point that out right.

995
00:51:09,600 --> 00:51:12,360
Speaker 3: It's not just people talk about, oh, we made it

996
00:51:12,440 --> 00:51:16,279
Speaker 3: with you know, Denisovans, yes, and had kids with them,

997
00:51:16,400 --> 00:51:20,520
Speaker 3: and those kids were you know, presumably loved, right. I mean,

998
00:51:20,800 --> 00:51:23,520
Speaker 3: we all know that that kids require a lot of care,

999
00:51:24,560 --> 00:51:27,320
Speaker 3: certainly when they're young, and so so somebody you know,

1000
00:51:27,880 --> 00:51:30,200
Speaker 3: cared enough for those kids to nurture them, and they

1001
00:51:30,280 --> 00:51:33,920
Speaker 3: survived and eventually some of their genes have ended up

1002
00:51:33,960 --> 00:51:36,240
Speaker 3: in us. So it's not a lot of their genes,

1003
00:51:36,320 --> 00:51:40,120
Speaker 3: So the highest percentages are like five percent Denisovans. So

1004
00:51:40,160 --> 00:51:43,400
Speaker 3: you can have individuals alive today who like five percent

1005
00:51:43,480 --> 00:51:46,600
Speaker 3: of their genes. So these are like the parts of

1006
00:51:46,680 --> 00:51:49,320
Speaker 3: our genome that, like, you know, the DNA is coding

1007
00:51:49,480 --> 00:51:53,000
Speaker 3: for a protein that does something in the body, about

1008
00:51:53,000 --> 00:51:56,880
Speaker 3: five percent of that could be traced back to Denisovan DNA.

1009
00:51:57,280 --> 00:51:59,759
Speaker 4: Wow, I'm intrigued by your use of the word us

1010
00:52:00,000 --> 00:52:02,560
Speaker 4: and denis Evans, Like, aren't we the Denisovans. Aren't we

1011
00:52:02,680 --> 00:52:04,600
Speaker 4: all just descendants of all these people?

1012
00:52:04,719 --> 00:52:07,960
Speaker 3: Yeah? Exactly, And so I think we're starting to come

1013
00:52:08,040 --> 00:52:10,480
Speaker 3: around to thinking about it exactly that way at least

1014
00:52:10,520 --> 00:52:10,839
Speaker 3: I am.

1015
00:52:11,000 --> 00:52:11,120
Speaker 4: Right.

1016
00:52:11,239 --> 00:52:14,200
Speaker 3: So when we say that we you know, we made

1017
00:52:14,200 --> 00:52:16,320
Speaker 3: it with them, we had kids with them, Like that

1018
00:52:16,520 --> 00:52:19,239
Speaker 3: gives you a sense of like, how did people at

1019
00:52:19,280 --> 00:52:23,320
Speaker 3: the time think about them? Right, Like, well, I'm fascinated

1020
00:52:23,360 --> 00:52:25,759
Speaker 3: by by imagining what that world was like with that

1021
00:52:25,880 --> 00:52:29,040
Speaker 3: interaction was like. And obviously we don't know any of

1022
00:52:29,120 --> 00:52:31,560
Speaker 3: the details about how the interaction took place, you know,

1023
00:52:31,719 --> 00:52:33,920
Speaker 3: was it consensual or not, who knows, But we do

1024
00:52:34,120 --> 00:52:36,400
Speaker 3: know that a child was conceived and that child was

1025
00:52:36,840 --> 00:52:38,840
Speaker 3: cared for, and that does I think tell us something.

1026
00:52:39,040 --> 00:52:40,480
Speaker 4: I mean, I've read Clan of the Cave there.

1027
00:52:40,640 --> 00:52:43,200
Speaker 3: Yeah, that's right, I mean that's exactly exactly.

1028
00:52:44,040 --> 00:52:46,440
Speaker 1: So there have been a lot of hominids. We argue

1029
00:52:46,480 --> 00:52:48,960
Speaker 1: about how many species there have been, but now there's

1030
00:52:49,040 --> 00:52:52,640
Speaker 1: only us. And so what happened to the rest of them?

1031
00:52:52,719 --> 00:52:55,360
Speaker 1: Did they breed with us and they're still with us today?

1032
00:52:55,480 --> 00:52:56,439
Speaker 1: Did they die off?

1033
00:52:56,560 --> 00:52:57,720
Speaker 5: What? What happened?

1034
00:52:57,960 --> 00:52:58,120
Speaker 1: Yeah?

1035
00:52:58,200 --> 00:53:00,160
Speaker 3: So I mean you can think in some sense that

1036
00:53:00,360 --> 00:53:02,920
Speaker 3: like Denis Evans and Neanderthals, because we have some you know,

1037
00:53:03,040 --> 00:53:06,719
Speaker 3: Neanderthal DNA in us today as well, in a sense

1038
00:53:06,760 --> 00:53:09,200
Speaker 3: they're still here. And as Daniel said, they are us, right,

1039
00:53:09,200 --> 00:53:11,279
Speaker 3: I mean, if we have their DNA, then why do

1040
00:53:11,400 --> 00:53:13,600
Speaker 3: we say that they're extinct. I think the thing is that,

1041
00:53:13,800 --> 00:53:16,800
Speaker 3: like now we have enough of fossil evidence, and we

1042
00:53:16,840 --> 00:53:19,360
Speaker 3: found more fossil evidence by the way, for Denisovans. So

1043
00:53:19,440 --> 00:53:21,680
Speaker 3: what I was talking about is the initial discovery. We

1044
00:53:21,760 --> 00:53:26,720
Speaker 3: have now found more fossils, including a very intact skull

1045
00:53:27,640 --> 00:53:30,279
Speaker 3: that has a fascinating backstory, and so we're starting to

1046
00:53:30,400 --> 00:53:34,200
Speaker 3: know more about what physical features they had. We do

1047
00:53:34,360 --> 00:53:36,960
Speaker 3: know a ton about the physical features of Neanderthals, which

1048
00:53:37,040 --> 00:53:40,640
Speaker 3: lived more in Europe and Central Asia and Western Asia,

1049
00:53:41,640 --> 00:53:45,359
Speaker 3: and so they had physical features that are different enough

1050
00:53:45,480 --> 00:53:48,439
Speaker 3: from people living today that you know, for the most part,

1051
00:53:48,560 --> 00:53:51,200
Speaker 3: what people say is, you know, wouldn't pass the subway test, right,

1052
00:53:51,239 --> 00:53:54,279
Speaker 3: which is to say that, like, you know, if a

1053
00:53:54,360 --> 00:53:58,360
Speaker 3: Neanderthal or Genisovan we're about to board a subway in

1054
00:53:58,440 --> 00:54:01,680
Speaker 3: New York or any city for that matter, you know,

1055
00:54:01,840 --> 00:54:03,560
Speaker 3: would would would someone look twice?

1056
00:54:03,920 --> 00:54:05,880
Speaker 4: That says a lot, because New York City has some

1057
00:54:05,960 --> 00:54:07,040
Speaker 4: weird people on the subway.

1058
00:54:07,160 --> 00:54:10,360
Speaker 3: Well exactly, I guess you know. That's why the subway

1059
00:54:10,440 --> 00:54:13,120
Speaker 3: test sort of rings true. It's like people are willing

1060
00:54:13,200 --> 00:54:16,080
Speaker 3: to accept a whole wide diversity of humanity as just

1061
00:54:16,160 --> 00:54:19,880
Speaker 3: being totally normal. But the Neanderthals, if a Neanderthal boarded

1062
00:54:19,920 --> 00:54:22,840
Speaker 3: the subway, you might look twice, you know. So in

1063
00:54:22,920 --> 00:54:26,279
Speaker 3: that sense, it's like, well, humans that look like that

1064
00:54:26,960 --> 00:54:29,880
Speaker 3: aren't around today, but they did leave a legacy. I mean,

1065
00:54:29,920 --> 00:54:33,160
Speaker 3: they left the legacy in our DNA. And there's interesting

1066
00:54:33,239 --> 00:54:38,480
Speaker 3: examples of like particular genes, traits, things that you know,

1067
00:54:38,960 --> 00:54:41,200
Speaker 3: happen in our bodies that we can actually trace back

1068
00:54:41,320 --> 00:54:45,280
Speaker 3: to Neanderthals and Denisovans in some cases amazing.

1069
00:54:45,600 --> 00:54:49,120
Speaker 1: But what happens to the Okay, so forget Denisovans and Neanderthals,

1070
00:54:49,200 --> 00:54:50,759
Speaker 1: the rest of them, Where did they go?

1071
00:54:51,320 --> 00:54:55,800
Speaker 3: Yeah, So, in the case of other hominid species, partly

1072
00:54:55,880 --> 00:54:59,920
Speaker 3: we don't know whether any of their DNA has survived

1073
00:55:00,400 --> 00:55:03,520
Speaker 3: in modern humans because they lived long enough ago that

1074
00:55:03,600 --> 00:55:06,600
Speaker 3: we haven't been able to get any intact DNA from

1075
00:55:06,719 --> 00:55:09,160
Speaker 3: those fossils in order to be able to like understand

1076
00:55:09,239 --> 00:55:13,520
Speaker 3: their genetics. So it's possible that some of those older ones,

1077
00:55:13,640 --> 00:55:16,319
Speaker 3: like you know, homo Erectus for example, you know, there

1078
00:55:16,400 --> 00:55:18,920
Speaker 3: might be homoerectus genes in us today and we just

1079
00:55:18,960 --> 00:55:20,920
Speaker 3: don't know because we haven't been able to look at

1080
00:55:20,960 --> 00:55:24,840
Speaker 3: a homo erectus genome. But in other cases, there's certainly

1081
00:55:24,880 --> 00:55:27,839
Speaker 3: lineages of haman Is that we don't think left any

1082
00:55:28,120 --> 00:55:30,920
Speaker 3: descendants that are still alive today. So yeah, there's a

1083
00:55:30,960 --> 00:55:33,560
Speaker 3: big question of like why us and not them, right,

1084
00:55:34,000 --> 00:55:36,920
Speaker 3: And there have been debates about did our ancestors kill them?

1085
00:55:37,200 --> 00:55:40,800
Speaker 3: Did we just outcompete them? We were smarter, we were faster,

1086
00:55:41,080 --> 00:55:44,840
Speaker 3: we were better at working together, you know, And so

1087
00:55:45,320 --> 00:55:47,680
Speaker 3: you know, the short answer is, we don't know. That's

1088
00:55:47,719 --> 00:55:52,040
Speaker 3: an ongoing debate. But I think the fascinating part that

1089
00:55:52,120 --> 00:55:55,120
Speaker 3: we now do have a better insight into from looking

1090
00:55:55,200 --> 00:55:57,520
Speaker 3: at Neanderthals and Denis Evans is that part of the

1091
00:55:57,600 --> 00:56:00,560
Speaker 3: answer is we mixed with them, we enter with them,

1092
00:56:01,160 --> 00:56:03,120
Speaker 3: and as you said, we are them in a sense

1093
00:56:03,160 --> 00:56:05,759
Speaker 3: and they are us, and they're still with us in

1094
00:56:05,840 --> 00:56:08,359
Speaker 3: some way, and maybe that was what happened further back

1095
00:56:08,400 --> 00:56:10,600
Speaker 3: as well. And we won't know until we're able to

1096
00:56:11,239 --> 00:56:16,759
Speaker 3: hopefully someday get some DNA or protein, some other kind

1097
00:56:16,800 --> 00:56:19,719
Speaker 3: of you know, molecular evidence that would allow us to

1098
00:56:20,360 --> 00:56:21,520
Speaker 3: answer some of those questions.

1099
00:56:21,880 --> 00:56:23,640
Speaker 4: And so as we look back in time, how far

1100
00:56:23,800 --> 00:56:28,240
Speaker 4: back would you consider our ancestors to be modern humans

1101
00:56:28,360 --> 00:56:30,280
Speaker 4: the kinds of people who would get on the subway

1102
00:56:30,760 --> 00:56:34,040
Speaker 4: or could just like be plopped into modern society, grow

1103
00:56:34,160 --> 00:56:36,600
Speaker 4: up in our schools and become a totally normal person.

1104
00:56:36,920 --> 00:56:39,719
Speaker 3: Yeah, so it's hard to say where we draw that line,

1105
00:56:39,760 --> 00:56:42,040
Speaker 3: but I mean one way to do it is to

1106
00:56:42,160 --> 00:56:46,239
Speaker 3: say our species Homo sapiens as we currently define it, right, So,

1107
00:56:47,040 --> 00:56:50,440
Speaker 3: you know, paleor anthropologists who study human evolution, they give

1108
00:56:50,480 --> 00:56:53,239
Speaker 3: a name, a species name to every fossil that they

1109
00:56:53,320 --> 00:56:56,680
Speaker 3: find or every you know, piece of fossil that they

1110
00:56:56,719 --> 00:56:59,759
Speaker 3: can get a genome from, and so only those that

1111
00:57:00,160 --> 00:57:03,600
Speaker 3: are given the name Homo sapiens are technically our species

1112
00:57:03,840 --> 00:57:06,759
Speaker 3: as we currently consider it. So the way you could

1113
00:57:06,760 --> 00:57:09,320
Speaker 3: answer that is how old is our species, Homo sapiens,

1114
00:57:09,920 --> 00:57:13,480
Speaker 3: And the answer is, yet again that people debate this,

1115
00:57:13,800 --> 00:57:17,120
Speaker 3: but it's between two hundred thousand and three hundred thousand

1116
00:57:17,200 --> 00:57:19,640
Speaker 3: years old. So that's kind of the brackets on when

1117
00:57:19,720 --> 00:57:25,040
Speaker 3: are the earliest fossils that some people attribute to Homo sapiens,

1118
00:57:25,680 --> 00:57:28,200
Speaker 3: So somewhere in the two hundred to three hundred thousand

1119
00:57:28,280 --> 00:57:31,120
Speaker 3: year old range, which again I always say, like to me,

1120
00:57:31,320 --> 00:57:34,400
Speaker 3: that's so recent, like our species is so new to

1121
00:57:34,560 --> 00:57:40,680
Speaker 3: this planet. That's yesterday in the perspective of evolutionary biology.

1122
00:57:41,120 --> 00:57:43,040
Speaker 4: But just to underscore that, you're saying, if you took

1123
00:57:43,080 --> 00:57:46,040
Speaker 4: a baby from a quarter million years ago and time

1124
00:57:46,120 --> 00:57:49,440
Speaker 4: traveled them into the future and were raised by a

1125
00:57:49,520 --> 00:57:51,800
Speaker 4: normal human family, they would be indistinguishable.

1126
00:57:52,120 --> 00:57:56,160
Speaker 3: Well, there are some ways in which anthropologists distinguish between

1127
00:57:56,800 --> 00:57:59,680
Speaker 3: what they call archaic Homo sapiens and what they call

1128
00:57:59,800 --> 00:58:03,240
Speaker 3: an atomically modern Homo sapiens. These are getting into like

1129
00:58:03,480 --> 00:58:07,320
Speaker 3: what I would consider to be pretty like nuanced anatomical

1130
00:58:07,400 --> 00:58:11,120
Speaker 3: differences in in you know, skull shape, in which features

1131
00:58:11,160 --> 00:58:14,320
Speaker 3: are slightly larger, and these types of things. So this

1132
00:58:14,520 --> 00:58:17,000
Speaker 3: is the sort of splitting hairs part of doing this

1133
00:58:17,240 --> 00:58:21,320
Speaker 3: kind of science that you know, can be challenging when

1134
00:58:21,360 --> 00:58:23,960
Speaker 3: you start to get into like reading the research papers.

1135
00:58:24,080 --> 00:58:27,360
Speaker 3: But you know, it's still Homo sapiens. So as far

1136
00:58:27,440 --> 00:58:30,800
Speaker 3: as I'm concerned, like, I think, you know, there's interesting

1137
00:58:31,080 --> 00:58:34,120
Speaker 3: certainly questions to ask about, like well, what changes were

1138
00:58:34,160 --> 00:58:38,320
Speaker 3: taking place? Certainly there, you know, must have been some differences,

1139
00:58:38,480 --> 00:58:41,440
Speaker 3: even if it's cultural differences between the people living then

1140
00:58:41,480 --> 00:58:45,440
Speaker 3: and the people living today, but anatomically physically right, Like

1141
00:58:45,680 --> 00:58:49,240
Speaker 3: if you look at the skull of an early Homo

1142
00:58:49,360 --> 00:58:53,360
Speaker 3: sapiens and the skull of somebody from today, they're very similar.

1143
00:58:53,520 --> 00:58:56,720
Speaker 3: I mean, they're very very much like us. You'd have

1144
00:58:56,760 --> 00:58:58,400
Speaker 3: a beer with them, I would. Yeah.

1145
00:59:00,000 --> 00:59:02,440
Speaker 1: I also feel like Daniel's question is like Laiden, with

1146
00:59:02,560 --> 00:59:05,600
Speaker 1: his assumption about what makes people human? Could they survive

1147
00:59:06,000 --> 00:59:08,200
Speaker 1: today in our modern era? And I think plenty of

1148
00:59:08,240 --> 00:59:11,840
Speaker 1: people would argue that that's not the important thing about humans.

1149
00:59:11,880 --> 00:59:15,760
Speaker 1: It's you know, maybe social behavior or language or chins.

1150
00:59:15,800 --> 00:59:17,920
Speaker 1: One of our listeners said, chins, and I don't understand

1151
00:59:17,920 --> 00:59:18,440
Speaker 1: the chin thing.

1152
00:59:18,600 --> 00:59:20,760
Speaker 3: The chin thing is super interesting because it's one of

1153
00:59:20,800 --> 00:59:23,640
Speaker 3: the few physical features you can see in the fossils

1154
00:59:24,120 --> 00:59:27,600
Speaker 3: that distinguish Homo sapiens from other species. We are the

1155
00:59:27,800 --> 00:59:30,640
Speaker 3: only hominid that has a chin. So what did the

1156
00:59:30,760 --> 00:59:34,680
Speaker 3: chin do for us? I don't think anybody really has

1157
00:59:34,720 --> 00:59:37,640
Speaker 3: given a satisfying answer to that one. It seems to

1158
00:59:37,680 --> 00:59:40,080
Speaker 3: be an example of a trait that comes about through evolution,

1159
00:59:40,800 --> 00:59:44,880
Speaker 3: maybe just randomly and persists. It doesn't not all the

1160
00:59:44,920 --> 00:59:48,160
Speaker 3: traits have to have an adaptive value, doesn't always have

1161
00:59:48,280 --> 00:59:50,360
Speaker 3: to be useful for something. They can just come about.

1162
00:59:50,440 --> 00:59:52,080
Speaker 3: But I do like my chin, so I'm glad we

1163
00:59:52,160 --> 00:59:52,400
Speaker 3: have them.

1164
00:59:52,520 --> 00:59:55,640
Speaker 1: I like mine too. All Right, that was fantastic, Scott.

1165
00:59:55,720 --> 00:59:57,960
Speaker 1: Thank you so much for telling us all about ancient humans.

1166
00:59:58,040 --> 01:00:00,560
Speaker 1: But you're not just interested in ancient humans, interested in

1167
01:00:00,720 --> 01:00:04,240
Speaker 1: like ancient human evolution and future human evolution. So tell

1168
01:00:04,320 --> 01:00:05,520
Speaker 1: us about your upcoming book.

1169
01:00:05,960 --> 01:00:08,480
Speaker 3: Yeah, well, I you know, I've been interested in like

1170
01:00:08,760 --> 01:00:13,760
Speaker 3: the idea that humans are still evolving for quite some time, right, So,

1171
01:00:14,040 --> 01:00:16,640
Speaker 3: so my first book, published in twenty sixteen, was called

1172
01:00:16,840 --> 01:00:20,440
Speaker 3: Future Humans Inside the Science of our Continuing evolution, and

1173
01:00:20,520 --> 01:00:23,320
Speaker 3: that's all about the ways in which you know, natural

1174
01:00:23,400 --> 01:00:27,360
Speaker 3: selection and other evolutionary processes have continued until today. But

1175
01:00:27,520 --> 01:00:32,720
Speaker 3: then more recently, I've been exploring this one particular possibility

1176
01:00:32,840 --> 01:00:35,760
Speaker 3: for our evolutionary future, and that is what would happen

1177
01:00:35,840 --> 01:00:39,640
Speaker 3: if some of us left Earth and created settlements on

1178
01:00:39,760 --> 01:00:43,080
Speaker 3: other planets, something that you have also thought quite a

1179
01:00:43,120 --> 01:00:45,760
Speaker 3: bit about, Kelly. I know, we've had lots of conversations

1180
01:00:45,800 --> 01:00:49,160
Speaker 3: about the idea of space settlement, and it's been super fun.

1181
01:00:49,440 --> 01:00:52,200
Speaker 1: I love our parallel careers. Your aunts and space and

1182
01:00:52,280 --> 01:00:54,720
Speaker 1: I'm parasites and space, and we're both in like an

1183
01:00:54,760 --> 01:00:58,280
Speaker 1: evolution in ecology sort of track and a space future

1184
01:00:58,280 --> 01:01:00,840
Speaker 1: of humans in space track And anyway, it's always fun

1185
01:01:00,880 --> 01:01:01,200
Speaker 1: talking to you.

1186
01:01:01,440 --> 01:01:03,000
Speaker 3: I guess that tells us that there's a lot of

1187
01:01:03,040 --> 01:01:07,760
Speaker 3: ways to get to space. Huh, that's right, And so yeah,

1188
01:01:07,880 --> 01:01:10,920
Speaker 3: I mean so basically, yeah, I've spent the last several

1189
01:01:11,080 --> 01:01:14,360
Speaker 3: years doing a deep dive into this question of you know,

1190
01:01:14,720 --> 01:01:19,400
Speaker 3: if at some point people are successful in creating space settlements,

1191
01:01:20,400 --> 01:01:22,800
Speaker 3: what would that mean for the people living in those

1192
01:01:22,800 --> 01:01:27,120
Speaker 3: space settlements, Like, what would happen to the descendants of

1193
01:01:27,280 --> 01:01:30,920
Speaker 3: those first pioneers, those first settlers on you know, Mars

1194
01:01:31,280 --> 01:01:34,120
Speaker 3: or anywhere else for that matter. You know, questions like

1195
01:01:34,520 --> 01:01:37,680
Speaker 3: could a baby born on Mars come back to Earth,

1196
01:01:38,280 --> 01:01:42,480
Speaker 3: and you know, would people gradually adapt to the conditions

1197
01:01:42,600 --> 01:01:46,160
Speaker 3: on that planet, and would they eventually become a new

1198
01:01:46,400 --> 01:01:49,919
Speaker 3: species of human. So yeah, So the book is called

1199
01:01:50,120 --> 01:01:53,760
Speaker 3: Becoming Martian How living in Space will change our bodies

1200
01:01:53,800 --> 01:01:57,960
Speaker 3: and minds And it comes out February seventeenth of twenty

1201
01:01:58,040 --> 01:02:01,680
Speaker 3: twenty six. So super excited, and it's actually already available

1202
01:02:01,720 --> 01:02:03,400
Speaker 3: for pre order if folks want to get a copy.

1203
01:02:03,680 --> 01:02:05,600
Speaker 1: And I got to read it, and I can say

1204
01:02:05,640 --> 01:02:07,520
Speaker 1: that it's amazing. And it starts with a full word

1205
01:02:07,600 --> 01:02:11,280
Speaker 1: by astronaut Scott Kelly, which is the wider Smiths didn't

1206
01:02:11,320 --> 01:02:15,040
Speaker 1: snag an astronaut forward, So bravo. Not that the Wiener

1207
01:02:15,080 --> 01:02:17,160
Speaker 1: Smiths are, you know, a bar against which anyone should

1208
01:02:17,200 --> 01:02:19,280
Speaker 1: judge themselves. But I was pretty excited you got an

1209
01:02:19,280 --> 01:02:20,080
Speaker 1: astronaut forward.

1210
01:02:20,280 --> 01:02:22,480
Speaker 3: Well, thank you, No, I was too. That was a

1211
01:02:22,600 --> 01:02:27,360
Speaker 3: real wonderful thing that Scott Kelly agreed to contribute a forward.

1212
01:02:28,400 --> 01:02:31,080
Speaker 3: But you and Zach actually helped tremendously with this book,

1213
01:02:31,120 --> 01:02:34,200
Speaker 3: both in terms of sharing ideas and notes and reading

1214
01:02:34,360 --> 01:02:37,240
Speaker 3: you know, draft copies and support all on the way.

1215
01:02:37,360 --> 01:02:38,720
Speaker 3: So super appreciate it.

1216
01:02:39,000 --> 01:02:42,360
Speaker 1: Our pleasure. Yay Space and yeay Scott. Okay, so everyone

1217
01:02:42,400 --> 01:02:45,520
Speaker 1: should pick up Becoming Martian and we'll see you on

1218
01:02:45,600 --> 01:02:46,360
Speaker 1: the next episode.

1219
01:02:46,400 --> 01:02:48,200
Speaker 3: Thanks everyone, thanks for having me on again.

1220
01:02:54,960 --> 01:02:58,760
Speaker 1: Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio. We

1221
01:02:58,840 --> 01:03:01,320
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1222
01:03:01,560 --> 01:03:04,240
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1223
01:03:04,520 --> 01:03:06,120
Speaker 4: Extraordinary Universe.

1224
01:03:06,280 --> 01:03:09,160
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1225
01:03:09,200 --> 01:03:12,200
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1226
01:03:12,240 --> 01:03:12,600
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1227
01:03:12,920 --> 01:03:16,400
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1228
01:03:16,480 --> 01:03:19,600
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1229
01:03:18,760 --> 01:03:20,800
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1230
01:03:20,920 --> 01:03:24,680
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1231
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1233
01:03:28,960 --> 01:03:30,440
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