Speaker 1: Welcome to Stuff to Blow your Mind from how Stuff
Speaker 1: Works dot com. Hey you welcome to Stuff to Blow
Speaker 1: your mind. My name is Robert Lamb and I'm Joe McCormick.
Speaker 1: And today we're talking about bipeds, bipedalism. Uh. And this
Speaker 1: is a this is a topic that I was just
Speaker 1: kind of rattling around my brain the other day because
Speaker 1: for most of us, walking is just kind of every day, right,
Speaker 1: you run a little bit, uh, maybe you hop a
Speaker 1: little bit. It's of course involved multiple times and mammals.
Speaker 1: You have macropods, kangaroo rats in my spring hair hopping,
Speaker 1: my pangolins, and of course homing a apes um much
Speaker 1: which includes ourselves and sometimes scientists, you know, make the
Speaker 1: distinction between facultative and obligate bypeds, though this isn't a
Speaker 1: standard distinction, suffice to say they're creatures such as the
Speaker 1: human flightless birds, and to draw on a prehistoric example,
Speaker 1: the t w rex, that have no real alternative to
Speaker 1: bipedal movement. I mean, I can crab walk around, Yeah,
Speaker 1: I wouldn't. If if you're crab walking, you're still bipedal
Speaker 1: unless you can grow some crab legs. It depends which
Speaker 1: version of the crab walk. Are you're talking, you're talking
Speaker 1: about where you're I'm talking where you know, you lean
Speaker 1: back and you go on all four your belly up
Speaker 1: in the air. Because there's also the Zoidberg walk, where
Speaker 1: you walk from side to side. That's a good one,
Speaker 1: but that's not that that would just be bi Zoidberg
Speaker 1: is a biped No no, no, no, I mean the
Speaker 1: the Exorcist down the stairs. Well oh yes, yes, okay,
Speaker 1: well that that would count, but I fully grant you
Speaker 1: I probably wouldn't get around very quickly doing that all
Speaker 1: the time. Other creatures, of course, are capable of bipedal locomotion,
Speaker 1: but only employed under certain circumstances, like, for instance, a
Speaker 1: lemur dancing you know, sort of prancing sideways across a
Speaker 1: clearing between two trees, a giant ground sloth in in
Speaker 1: in old and olden days, rising up to reach higher branches,
Speaker 1: or or one of my favorites, a cat standing on
Speaker 1: its hind lay eggs to better view pray or something
Speaker 1: of interest. This is always a creepy, weird side if
Speaker 1: you're lucky enough to witness it. Oh but it also
Speaker 1: can be very cute when dogs stand on two legs
Speaker 1: to to get up there closer to the treat that
Speaker 1: they want. Oh, yeah, it's adorable. It's yeah. When dogs
Speaker 1: do it, it's adorable. When cats do it, it is
Speaker 1: it's a little unsettling, like they've suddenly become tiny people,
Speaker 1: like they've been people all along, um or that's my
Speaker 1: read on it. Now. When it comes to the hominans,
Speaker 1: which again includes humans, the oldest evidence of bipedal movement
Speaker 1: in a hominant species was probably six million years ago.
Speaker 1: This would have been the selmthropists, and there's some dispute
Speaker 1: over this, but any rate, we were mostly bipedal by
Speaker 1: say four million years ago. We had a curved spine
Speaker 1: by two point five million years ago, and it altered
Speaker 1: our hip support by one point nine five million years ago,
Speaker 1: and we were fully bipedal by the time of Fomo erectus,
Speaker 1: with signature pelvis and thigh bones evident in the fossil record.
Speaker 1: The legs lengthened over time, allowing for longer strides everything
Speaker 1: that would enable the ministry of silly walks to do
Speaker 1: its thing. Yeah. Now, some of what we know about
Speaker 1: the posture and gate of our ancient ancestors and their
Speaker 1: close relatives has to be inferred indirectly. I mean, you
Speaker 1: can get a pretty good idea from like the shapes
Speaker 1: of bones and stuff that that will tell you a lot.
Speaker 1: There's other there's other evidence that's very direct. A great
Speaker 1: piece of early direct evidence for bipedality is the fossil
Speaker 1: formation known as the Late Totally Footprints. So, Robert, have
Speaker 1: you have you seen what these look like? I think
Speaker 1: I have everybody very cool in In nineteen seventy six
Speaker 1: there was a team working with the paleontologist Mary Leaky,
Speaker 1: and they discovered a collection of fossilized animal tracks in
Speaker 1: late Totally Tanzania, which is south of the Old Duvai Gorge.
Speaker 1: And the tracks were preserved in what had been a
Speaker 1: soft bed of volcanic ash about three point six million
Speaker 1: years ago or three point three point six three point
Speaker 1: seven uh and it had hardened and been preserved for
Speaker 1: us to discover in the twentieth century. And then so
Speaker 1: after these tracks were initially discovered, in nineteen seventy eight,
Speaker 1: Paul Able, a colleague of Leaky's, discovered that the formation
Speaker 1: also contained a twenty seven meter or about eighty eight
Speaker 1: foot long trail of ancient hominin footprints in addition to
Speaker 1: the other animal footprints, probably made by Australian Epithecus afarensis,
Speaker 1: the species to which Lucy belonged, And there were about
Speaker 1: seventy hominin footprints at all in all in this formation.
Speaker 1: And so the thing about these footprints is they're quite
Speaker 1: clearly bipedal. You know, you're not seeing four legged movement,
Speaker 1: and somebody was just walking on two feet through this
Speaker 1: volcanic ash. The prints i've read are space close together,
Speaker 1: meaning a short stride might mean short legs. And the
Speaker 1: prints also show a big toe in line with the
Speaker 1: foot rather than opposed to the foot, as you see
Speaker 1: in arboreal apes. So like you know, your human big
Speaker 1: toes go straight out, the arboreal apes have more kind
Speaker 1: of a toe thumb, like a big toe thumb, uh,
Speaker 1: that they used to climb trees and grab hold of stuff.
Speaker 1: And also their footfalls apparently went heel toe, just like
Speaker 1: ours tend to. So by about three point six million
Speaker 1: years ago, we we've got direct evidence that our ancestors
Speaker 1: and their close relatives were walking on two feet. Uh.
Speaker 1: And I also can't help but mention I've read supposedly
Speaker 1: there's this story of how the prints were discovered because
Speaker 1: one of Leaky's colleagues, a paleo anthropologist named Andrew hill Uh,
Speaker 1: stumbled across the fossil formation when he and another colleague
Speaker 1: were running around throwing elephant poop at each other. Oh well,
Speaker 1: you know you gotta keep it lighthearted on the dick, right, So, um,
Speaker 1: like you said, we we know all of this based
Speaker 1: on mostly fossil remains, and by that this, you know,
Speaker 1: we're looking at the bones of our ancestors and observing
Speaker 1: what the gradual shift to bipedalism did to us. And
Speaker 1: it certainly certainly came at a cost. Yeah, now, to
Speaker 1: be sure it was it was worth it, I guess.
Speaker 1: I mean. It made it easier for us to pick
Speaker 1: up fruits and pick up pick from a low line branches.
Speaker 1: It gave us free hands for carrying food and also
Speaker 1: very importantly carrying tools, carrying our young as well. It
Speaker 1: allowed us to rise up and appear larger and more
Speaker 1: fearsome to our enemies. Are many enemies of the wild.
Speaker 1: This is something that I think we often don't think about.
Speaker 1: But unless you're being instructed on how to react to
Speaker 1: a bear in the win the wild, you know, they say,
Speaker 1: make yourself as big as possible, and certainly there are
Speaker 1: other animals that do just the same thing, but that's
Speaker 1: one of the strengths of being able to at least
Speaker 1: rise up on two feet. Yeah, now you can't know
Speaker 1: this for sure, but I tend to think that bipedalism
Speaker 1: is a sort of necessary precursor to advanced tool using intelligence.
Speaker 1: I mean, you see some use of tools in quadrupedal apes,
Speaker 1: but the fact that the fact that you're walking on
Speaker 1: two feet gives you free hands, and having free hands,
Speaker 1: it seems like suddenly you've got much more incentive to
Speaker 1: be using them for all kinds of stuff. Well, it's
Speaker 1: interesting when you think about the animals that do display
Speaker 1: some form of tool use. I mean, certainly you have
Speaker 1: the the apes, which are going to more or less
Speaker 1: aligned with the human experience of tool use. But then
Speaker 1: of course you have like the corvids uh and uh
Speaker 1: and a few other birds that that also use tools. Now,
Speaker 1: obviously they are engaging in bipedal ground movement. Their wings
Speaker 1: are tucked away, but it's perhaps and it's a slightly
Speaker 1: different situation with birds because those wings do have a purpose. Uh,
Speaker 1: They've just specialized their their their beak functionality, and I've
Speaker 1: learned how to use tools with that. The same is
Speaker 1: truy of dolphins. You know they're using when they engage
Speaker 1: in tool use, are using their snout um octopi slightly
Speaker 1: different situation they have they have They have a wide
Speaker 1: variety of limbs and are not necessarily gonna become bipedal
Speaker 1: anytime soon. So anyway you shake it the back to
Speaker 1: the human scenario, it helped us expand our range. It
Speaker 1: It definitely played a part in our our ascension or dominance,
Speaker 1: certainly our ability to invent things and expand, but we
Speaker 1: also paid a price. We had to distribute all of
Speaker 1: our weights on two limbs, resulting in all sorts of
Speaker 1: painful experiences such as a lower back pain, slip discs,
Speaker 1: arthritis in the lower body, fallen arches. Our spines are
Speaker 1: ultimately just kind of weird. We evolved wider hips and
Speaker 1: stronger knees to kind of cope with it to a
Speaker 1: certain extent. But this is the reason that roughly of
Speaker 1: adult humans will experience back pain in their lives. I
Speaker 1: would say one of the biggest anatomical drawbacks is that
Speaker 1: we can make finger guns at each other. I mean
Speaker 1: that that is a true blow to the species you mean,
Speaker 1: I mean the beneficial kind where like kids playing cowboys
Speaker 1: and Indians or whatever on the playground, know the like
Speaker 1: the like catch you later, bro Okay. So also it
Speaker 1: also affected the way that we give birth and uh
Speaker 1: and this is a I have to say, this is
Speaker 1: a topic that we could easily have devoted an entire episode.
Speaker 1: There's a lot of scholarship and debate on exactly how
Speaker 1: the modern human birthing scenario pans out towards prehistoric examples,
Speaker 1: but the move towards the bipedal form changed our skeletons.
Speaker 1: This affected the pelvis. Most primates have a pretty straight
Speaker 1: birth canal, but hominans soon boasted a narrow, distorted, kind
Speaker 1: of fun house tube of a birth canal. The offspring
Speaker 1: had to twist and turn in order to pass through.
Speaker 1: This is true of our our ancestors. But our bodies
Speaker 1: continued to evolve. We became taller, we grew larger brains.
Speaker 1: That means meant bigger brained babies having to make it
Speaker 1: through that twisting tunnel. Everything became tighter. Child birth became
Speaker 1: a potentially more dangerous affair, because it also means giving
Speaker 1: birth to a child an earlier stage of its development
Speaker 1: in order to actually break it free from the confines
Speaker 1: of our bipedally twisted bodies. Now, again, there's a lot
Speaker 1: more to this. Scientists have gone back and forth on
Speaker 1: the so called obstetric dilemma, but bipedal evolution certainly changed things.
Speaker 1: All right, I think we should take a quick break.
Speaker 1: We will be right back to discuss why bipedalism evolved
Speaker 1: in humans. Thank alright, we're back. So this is a
Speaker 1: big question because certainly we can point to all of
Speaker 1: these like the pros and all the cons, but like,
Speaker 1: what is the driving force right right now? What caused
Speaker 1: our our ancient hominin ancestors to go on two legs? Primarily,
Speaker 1: why did our ancestors become bipetle And this is an
Speaker 1: ongoing debate. We know at some point we transitioned from
Speaker 1: mostly four footed gate to a mostly two footed gate,
Speaker 1: but why did it happen and what type of pressure
Speaker 1: selected for this? So, first of all, when answering questions
Speaker 1: like this, it's often hard to be certain, right, you know,
Speaker 1: we only have the evidence we can find. Fossil evidence helps,
Speaker 1: but it's hard to like run new experiments to test this.
Speaker 1: We you know, we only have the fossil finds we
Speaker 1: have and can only draw the conclusions we can draw
Speaker 1: from them. And there have been all kinds of answers
Speaker 1: over the years. So for a long time, consensus seem
Speaker 1: to be that bipedalism was an adaptation to a change
Speaker 1: in our primary habitat, as our ancestors moved down out
Speaker 1: of the trees into a flat grassland, perhaps driven by
Speaker 1: changing climate, like changing climate killed off forests and left
Speaker 1: these you know, savannahs with tall grasses in their place,
Speaker 1: or these creatures just moved down into the savannahs to
Speaker 1: follow food sources or something. In this case, uh, these
Speaker 1: hominins needed to stand up to see over the tall grass.
Speaker 1: And this explanation is not still favored. This has fallen
Speaker 1: out of favor among experts, and one reason is that
Speaker 1: climate history analysis and physical fossil evidence indicate that we
Speaker 1: were becoming bipedal at the same time that we were
Speaker 1: still adapted to climbing and living in trees. And I
Speaker 1: think there are multiple lines of evidence supporting this. It
Speaker 1: appears that at some point our ancestors were both like
Speaker 1: living in forests and climbing trees, but also having skeletons.
Speaker 1: That's supported bipedal walking gate. Also, it's worth pointing out
Speaker 1: that plenty of other animals that occupy areas with tall
Speaker 1: grasses tall grasslands do just find staying on all fours right.
Speaker 1: They don't need to stand up to see over the
Speaker 1: grass in order to survive. Like grassland baboons today are
Speaker 1: still quadrupedal. So that used to be what people thought,
Speaker 1: but that is not no longer the main hypothesis. So
Speaker 1: another theory that is popular with the public but not
Speaker 1: with scientists in the relevant fields is the much much
Speaker 1: beloved aquatic ape theory. Oh yes, we talked about this
Speaker 1: um last year. Yeah, and our Aquatic Humanoids episode. We
Speaker 1: concluded that there's not really any good evidence for this.
Speaker 1: There's no direct fossil evidence for whatsoever. And the indirect
Speaker 1: reasoning that causes people to think that there's evidence for
Speaker 1: this is, uh, it's just not very good. But we
Speaker 1: should mention it because this is bound to come up
Speaker 1: whenever people address bipedality in its origins. I think it's
Speaker 1: just because it's fun to imagine, maybe, and because it's
Speaker 1: unconventional that makes it more interesting to people. Basically, it
Speaker 1: says that the explanation for the main phenotypic variations between
Speaker 1: us and our closest ape relatives is that our direct
Speaker 1: ancestors briefly evolved to become water dwelling primates so sort
Speaker 1: of like fishmen and uh, and then moved back to
Speaker 1: dry land after that. And under this theory, bipedality evolves
Speaker 1: because we need to keep our heads above water when
Speaker 1: we're waiting around in search of shellfish for food. All Right,
Speaker 1: it would be kind of like the idea that that
Speaker 1: we became bipedal because we didn't want to get our
Speaker 1: t shirts wet, you know, I mean, it's it's not
Speaker 1: that bad, but yeah. So this was first proposed by
Speaker 1: Alistair Hardy, and it was mainly developed by somebody named
Speaker 1: Elaine Morgan. And in short, Morgan says, look, we're the
Speaker 1: only mammal that consistently walks on two legs, but some
Speaker 1: four legged animals can occasionally stand up on two legs
Speaker 1: and wind. Do our closest stape relatives walk on two legs? Well?
Speaker 1: She claims there's only one circumstance when they always walk
Speaker 1: on two legs, and that's when they're waiting in water.
Speaker 1: I see some pretty clear evidence running counter to this assertion,
Speaker 1: just in publicly available video like primates. You look this up.
Speaker 1: Primates sometimes stand up on two legs for all kinds
Speaker 1: of reasons while carrying objects and moving around with them
Speaker 1: during dominance displays to reach something like they don't. And
Speaker 1: they also, on top of that, don't always stand up
Speaker 1: when waiting in water. I found video of guerrillas waiting
Speaker 1: around in water, and they tend to stay on all fours.
Speaker 1: So if the classic explanation about seeing over the grass
Speaker 1: is probably wrong and we don't put any stock in
Speaker 1: the aquatic ape, what is the real explanation? Of course,
Speaker 1: we still don't know, but there are a lot of
Speaker 1: competing theories. Maybe there was a selection pressure on having
Speaker 1: free hands, so maybe some of our ancestors began carrying
Speaker 1: or throwing things, and for some reason this got started,
Speaker 1: and then there was a great survival or reproduction advantage
Speaker 1: for the ones that did this more and more of
Speaker 1: the time. So being able this comes back to the
Speaker 1: examples of being able to carry ones young, being able
Speaker 1: to carry food that you've gathered, or being able to
Speaker 1: carry a tool or a weapon, say a nice you
Speaker 1: know jaw bone for smacking the other epe creatures around. Well,
Speaker 1: I mean a big one I've seen suggested actually is throwing,
Speaker 1: Like if if we evolved somehow a throwing hunting strategy
Speaker 1: where you would throw objects, that this could have spurred
Speaker 1: bipedality or some bridge to it. Another thing I was
Speaker 1: reading about in a BBC article is that recent research
Speaker 1: has suggested that perhaps partial bipedality helped these hominins adapt
Speaker 1: to rocky, uneven terrain in geologically active areas. Essentially that
Speaker 1: our ancestors were not only tree climbers, but rock climbers,
Speaker 1: and this encouraged them to take on some traits that
Speaker 1: bridge the gap to bipedalism. Another is, I guess sort
Speaker 1: of the least the least interesting is an idea but
Speaker 1: has seems to have a lot going for it, And
Speaker 1: it's simply that a certain kind of bipedalism in tree
Speaker 1: dwelling life became useful, as it is in many orangutans today.
Speaker 1: Like you can look at orangutans living in the trees
Speaker 1: that walk around on two feet, like they'll reach up
Speaker 1: and grab branches with their arms over their heads while
Speaker 1: walking around on other branches with two feet, it's just
Speaker 1: a great way to anchor yourself between a lower and
Speaker 1: upper branch. So there are a lot of competing theories.
Speaker 1: I mean, I know there are other ones we didn't
Speaker 1: even cover here, but this is this is an unsolved question.
Speaker 1: We still don't know the answer now anyway to shake it.
Speaker 1: We were not the first bipeds, not even close. I
Speaker 1: already mentioned the t rex, you know that, that famous
Speaker 1: the famous Cretaceous period, the carnivore Cretaceous spirit, of course,
Speaker 1: banned hundred forty five million years ago to sixty six
Speaker 1: million years ago. And this again, it's just an animal
Speaker 1: that could scarcely be more of a biped you know,
Speaker 1: those tiny little arms. And of course he or she
Speaker 1: is just one of the many therapods that roamed the
Speaker 1: prehistoric Earth, and in many cases not not not just
Speaker 1: roamed it, but ran after their prey, running a key
Speaker 1: advantage of their bipedal morphology. But even they, it seems
Speaker 1: we're not the first. Um there's a two hundred and
Speaker 1: ninety million year old fossil of a species that is
Speaker 1: dubbed ood Obama's Kersaurus. This is a creature that was
Speaker 1: very lizard like it seems, and it's a probable appearance,
Speaker 1: had short fore limbs, relatively long tail and high and
Speaker 1: also relatively long hind limbs. So these are kind of
Speaker 1: the hallmarks of of a bipedal creature. But the other
Speaker 1: curious thing about it is that it seems to have
Speaker 1: been a herbivore rather than a meat eat or like
Speaker 1: the theropods. Therefore it probably palin. I just think it
Speaker 1: probably depended on bipedal running to flee from quadrupedal danger.
Speaker 1: And on the subject of dinosaurs and quadrupedal and bipedal arrangement,
Speaker 1: I found a two thousand five article in Astrobiology magazine
Speaker 1: that brings up a species that is dubbed Masso spondulous.
Speaker 1: And this is a pro sorrow pod now Sara pods
Speaker 1: as everyone remember that. You know, they're the giant Diplodocus
Speaker 1: Brachiosaurus style kind of creatures, you know, big, enormous quadrupeds.
Speaker 1: It just enormous, just ponderous creatures. The pro sauropods, unlike
Speaker 1: their descendants, they could rise up on their hind legs
Speaker 1: and go after food bi petally. So back in two
Speaker 1: thousand five, University of Toronto at Mississaugua thiss ut M
Speaker 1: biology professor Robert Rice. He looked at an embryo of
Speaker 1: one of these massospondulous creatures and he found the thing
Speaker 1: was that it looked like a four legged saara pod.
Speaker 1: So he hypothesized that it would have grown into a
Speaker 1: full bipedal form as it matured. Uh this is what
Speaker 1: he told Astro Astrobiology magazine quote. Because the embryo of
Speaker 1: massospondos looks like a tiny saua pod with massive limbs
Speaker 1: in a quadrupedal gait. We proposed in our paper that
Speaker 1: the sauropods gate probably evolved through a phenomenon called ptomorphosis,
Speaker 1: the retention of embryonic and juvenile features in the adult.
Speaker 1: So this is interesting cause we're talking about a creature
Speaker 1: that potentially adapted bipedal, the bipedal gate, but then left
Speaker 1: it behind. Uh paedomor morphosis. By the way, it's it's
Speaker 1: something we see today in various amphibian speeches species. But
Speaker 1: for for these saua pods and for the true sauropods,
Speaker 1: it would mean that they were essentially man babies of
Speaker 1: the prehistoric world, like they simply no longer had to
Speaker 1: grow up like they were the biggest forest eating dumpsters
Speaker 1: on the planet, and therefore they really didn't have to
Speaker 1: augment their more or less larval form anymore. You know,
Speaker 1: I have often wondered something when looking at bipedal therapod
Speaker 1: dinosaurs like the t rex. Just look at that powerful
Speaker 1: lower body and then the tiny little baby arms out front.
Speaker 1: If this dinosaur fell down or even just you know,
Speaker 1: went to have a little lie down in the meadow,
Speaker 1: how did it get back up. I'm not saying it
Speaker 1: would be impossible, it just seems very awkward. Of course,
Speaker 1: we're by peedle and we can get up from the ground,
Speaker 1: but we have long arms and strong upper bodies to
Speaker 1: help us. Try lying down on the ground and then
Speaker 1: getting up without using your arms at all. You can
Speaker 1: probably do it, but it's not so easy, is it?
Speaker 1: And the t rex probably has an even lower relative
Speaker 1: center of mass than you. So what's going on? Like,
Speaker 1: was it this much of a struggle for the t
Speaker 1: rex every time it had to get up from the ground.
Speaker 1: That's a great question. Well, I've been wondering this for
Speaker 1: a while. I finally looked it up. There's actually a
Speaker 1: really good explainer on this in Scientific American provided by
Speaker 1: the paleontologist Gregory M. Ericson of Florida State University. And
Speaker 1: so here's what Erickson says. First of all, there has
Speaker 1: long been a dispute over exactly what the t rex
Speaker 1: is tiny four limbs were four uh maybe you know.
Speaker 1: One idea says, maybe they're just a vestigial, meaning they're
Speaker 1: actually not good for much of anything at all, and
Speaker 1: they only existed in diminished form because the rex hadn't
Speaker 1: fully lost them yet. And then the next idea says, well,
Speaker 1: maybe they're grasping arms used in copulation. And then the
Speaker 1: next idea says, maybe there's some sort of meat hook
Speaker 1: for feeding chunks of flesh into the mouth. Though this
Speaker 1: hypothesis was beaten down when it became clear that the
Speaker 1: arms of a t rex could not reach its mouth. Yeah,
Speaker 1: this is one of those things that when we went
Speaker 1: to the museum in Chicago, the Field Museum, that became obvious.
Speaker 1: You can when you go up to the arm, Uh,
Speaker 1: the fossil bones of the t rex's arm, they are
Speaker 1: the size of my arm. But the t rex is
Speaker 1: the size of like a two story house. And uh,
Speaker 1: clearly this is a shrunken limb exactly. But another hypothesis
Speaker 1: is that the baby arms were useful exactly for helping
Speaker 1: the t rex get back up when it was lying
Speaker 1: on the ground. So in the year nine seventy, the
Speaker 1: British paleontologist Barney Newman speculated that maybe the arms could
Speaker 1: help the t rex do a do a thing kind
Speaker 1: of like a push up. It would be a push
Speaker 1: up motion where the where it would help the rex
Speaker 1: keep from sliding forward along the ground as it tried
Speaker 1: to raise its body to a standing position. Just imagine
Speaker 1: trying to rise without anything to brace you, like lie
Speaker 1: flat on your stomach and then try to push yourself
Speaker 1: up to standing using your legs alone. You might be
Speaker 1: able to do it, but it's not easy. It's a
Speaker 1: lot easier if you can use your arms right, and
Speaker 1: it requires a fair amount of sort of coiling and
Speaker 1: slithering around for for most people, I think, And it's
Speaker 1: it's easier to imagine that kind of movement in our
Speaker 1: bodies as opposed to the t rex. Yes, so Ericson says,
Speaker 1: you know, now we know more about the biomechanics of
Speaker 1: the t rex than we did back when these ideas
Speaker 1: were hypothesized. So of course, and I'm one. As we mentioned,
Speaker 1: the arms can't reach them out the mouth, so the
Speaker 1: meat hook theory that's dead. One thing we have learned
Speaker 1: is that t rex arms were often broken during life,
Speaker 1: as opposed to in an injury that immediately caused death.
Speaker 1: And this tells us some interesting things. First of all,
Speaker 1: it tells us that the arms were probably kind of
Speaker 1: bad at whatever the rexes were using them for. And
Speaker 1: number two, they were not absolutely necessary for survival. The
Speaker 1: fact that we could have like examples of them having
Speaker 1: healed or not immediately killed the rex means that the
Speaker 1: rex could break an arm and survive for at least
Speaker 1: a month afterward. If an animal in the wild breaks
Speaker 1: a survival essential limb, that I mean that animal is
Speaker 1: generally pretty much done for, right, like a cheetah breaking
Speaker 1: a leg, etcetera. It's it's, it's done. And this suggests
Speaker 1: four limbs that were not survival essential. Also, though the
Speaker 1: rex arms would have been strong by our standards, like
Speaker 1: he says they could probably curl four hundred pounds, they
Speaker 1: would not have had strong enough bone structure in the
Speaker 1: wrists to lift what he calls large mechanical loads, and
Speaker 1: that would include the rex's own body. So this means
Speaker 1: Newman's push up hypothesis is probably wrong, right, that the
Speaker 1: t rex did a push up in order to get
Speaker 1: up from the ground. So how did they get up
Speaker 1: once they were lying down? Well Ericson suggests looking to
Speaker 1: birds who get up without the aid of four limbs,
Speaker 1: and apparently what they do is they simply tuck their
Speaker 1: legs directly underneath their center of gravity and then push
Speaker 1: straight up. Actually, probably sort of the exact same thing
Speaker 1: you would do if you tried to stand up from
Speaker 1: the ground without using your arms. You try to gather
Speaker 1: your legs under you and then push up right. Yeah, exactly.
Speaker 1: But also therapod dinosaurs with tiny arms like the t
Speaker 1: rex would have had the aid of their tails to
Speaker 1: help gain additional leverage or bracing against the ground. So
Speaker 1: the way I'm imagining this I could be wrong, but
Speaker 1: it's the same way you would brace your hands against
Speaker 1: the ground in front of you while extending your legs
Speaker 1: to stand up. Imagine a t rex may being able
Speaker 1: to brace its tail against the ground behind it while
Speaker 1: pushing up with its legs, a sort of backwards standing.
Speaker 1: You know, all of this, I think it goes It's
Speaker 1: just another reminder that the t Rex one of the
Speaker 1: most famous dinosaurs, if not the most famous dinosaur, that
Speaker 1: was the specimen out there, and also one that we
Speaker 1: we know a fair amount about there in a number
Speaker 1: of the fossils that have been found, and yet there
Speaker 1: are there's there's so much that we do not know
Speaker 1: about the t Rex. There are things about it that
Speaker 1: we will we will never know unless we get that
Speaker 1: time machine to go back and start hunting them, or
Speaker 1: if we somehow bring them back to life with a
Speaker 1: Jurassic Park scenario. I propose a pre emptive ban on
Speaker 1: dinosaur hunting before we have any time machines. We've got
Speaker 1: to get the regulations in place. That's right, We've got
Speaker 1: to think ahead of our technology. Alright. Well, on that note,
Speaker 1: we're going to take a quick break and we'll be
Speaker 1: right back. Thank alright, we're back, alright. So one of
Speaker 1: the big questions I had to in all of this is, alright,
Speaker 1: we we've looked at bipeds in prehistoric times, look at
Speaker 1: the bipedal world around us, uh that the humans have built.
Speaker 1: We're always trying to figure out what's going on or
Speaker 1: what could be going on in other worlds, What other
Speaker 1: kinds of life have evolved, are evolving, or will evolve
Speaker 1: in the future. So, assuming the entire universe isn't dead
Speaker 1: other than us, which you know, might be right. So, um,
Speaker 1: what's the deal? Would we find legged creatures on other worlds?
Speaker 1: And if we did, would we find bipedal creatures? We
Speaker 1: can certainly imagine extraterrestrial life that doesn't depend on legged locomotion,
Speaker 1: but intelligent life, life capable of achieving technology along the
Speaker 1: same lines as the human model. You know, we've we've
Speaker 1: got into this a bit in the past, discussing the
Speaker 1: notion of say a hypothetical aquatic species and what sort
Speaker 1: of technology they might be able to develop. Uh. As
Speaker 1: technico technology entails the mina manipulation of matter, one would
Speaker 1: need some sort of limbs of manipulation. Now, terrestrial nature
Speaker 1: provides us with other forms of manipulation beyond UH. You know,
Speaker 1: our hands, in our arms, they are the arms and
Speaker 1: tentacles of cephalopods. Uh, one could maybe turned to pseudopods
Speaker 1: and UH and other organisms so they're not used for
Speaker 1: tool use. But if we're just imagining some sort of
Speaker 1: an organism manipulating things, I think pseudopods are on the table.
Speaker 1: I just had a crazy idea, what about a magnetic organism,
Speaker 1: like it's got like a skin surface that can manipulate
Speaker 1: things by changing magnetic attraction or yeah, or it's picked up.
Speaker 1: I mean there are animals in the natural world that
Speaker 1: utilize magnetism to a certain extent, right, so maybe there's
Speaker 1: something there. Um. But when we try and think of
Speaker 1: tool users that engage in tool use, uh without engaging
Speaker 1: in pipedal movement, well, you know, a few varieties of
Speaker 1: of octopus come to mind. Uh. We can think of dolphins,
Speaker 1: and we of course do see a lot of bipedole
Speaker 1: use in apes and birds. But then we have these
Speaker 1: animals that engage in tool use via the mouthparts or
Speaker 1: in the case of elephants, with their trunks. You know
Speaker 1: Ian M. Banks, the sci Fia writer, he actually explored
Speaker 1: this idea, uh in his excellent novel Surface Detail. There
Speaker 1: are these creatures called the the pav Pavoolians, and they
Speaker 1: are they're like an elephant like quadrupedal species, but they
Speaker 1: have a pair of trunks that they use for tool use.
Speaker 1: In computer interface in the front, now, I was looking
Speaker 1: around for for any writings on this subject, and I
Speaker 1: ran across UH this paper Some engineering considerations on the
Speaker 1: controversial issue of humanoids by Gean Carlo Guinta from the
Speaker 1: Department of Mechanics and UH. This is UH from the
Speaker 1: Polytechnico Deterreno and this was collected in Cellular Origin, Life
Speaker 1: and Extreme Habitats and Astrobiology and UH. Guinta actually lays
Speaker 1: out much of what I said concerning UH possible mobility methods,
Speaker 1: UH and more in a very succinct way. He writes, quote,
Speaker 1: mobility of a living being is strictly linked with how
Speaker 1: it gets its food and energy. Autotrophic beings may not
Speaker 1: need any sort of mobility, while heterotrophic ones and particularly predators,
Speaker 1: usually need to move to obtain food. Large animals either
Speaker 1: are supported on a solid surface, float in a fluid
Speaker 1: under the effect of hydrostatic forces, or fly using aerodynamic forces.
Speaker 1: Very small beings may use other supporting mechanisms like surface tension,
Speaker 1: molecular interactions, etcetera. Since it is likely that an intelligent
Speaker 1: being has a minimum size larger than allowing to to
Speaker 1: use these mechanisms, they will not be considered. Other solutions
Speaker 1: like magnetic levitation or jets are conceivable, but are quite
Speaker 1: hypothetical and will not be considered and uh. He goes
Speaker 1: on to point out that most animals on solid surface
Speaker 1: surfaces do have legs, and the evolution on our planet
Speaker 1: at least is characterized by a gradual reduction in the
Speaker 1: number of legs. He continues quote in general, the large
Speaker 1: is the animal and the lower is the gravity of
Speaker 1: the planet. The easier it is to remain an equilibrium
Speaker 1: on a small number of legs, in the sense that
Speaker 1: the response of the nervous system to avoid falling down
Speaker 1: maybe less quick. From this point of view, low gravity,
Speaker 1: uh simplifies all operations related to motion. They go on
Speaker 1: to point out that the speed is important, that speed
Speaker 1: of course, is important for survival and uh and it's
Speaker 1: an important factor in natural selection. And we can see
Speaker 1: this reflected in our dinosaur examples, right, are prehistoric creature examples,
Speaker 1: because something like the t rex is running quickly to
Speaker 1: catch prey, as are its theropod um um uh kin.
Speaker 1: And then that earlier example, the kind of weird lizard
Speaker 1: herbivore that would have conceivably been running to escape from predator.
Speaker 1: It seems another example where so much in evolution ends
Speaker 1: up having to do with speed. Like you know, when
Speaker 1: we talked about what called the ideas behind what caused
Speaker 1: the Cambrian explosion, you know, this is another big open
Speaker 1: question in UH, in paleon oology and in the history
Speaker 1: of biology and evolution UH. And one of the ideas
Speaker 1: there is that maybe suddenly the introduction of predation into
Speaker 1: the food chain drove an explosion in body plan adaptation
Speaker 1: because suddenly things needed to protect themselves and move quickly
Speaker 1: in order to survive or in order to well sylvia,
Speaker 1: in order to survive, to catch or evade predation. Indeed,
Speaker 1: so again to continues and says that all of this
Speaker 1: UH means there will be quote a strong incentive to
Speaker 1: shift from walking a sequel of static equilibrium positions to running,
Speaker 1: which includes positions in which static equilibrium is not guaranteed.
Speaker 1: Large animals, possibly with a smaller number of legs may
Speaker 1: have been an advantage, and bipeds are a very good
Speaker 1: configuration for beings having an adequate controlled system. This is interesting.
Speaker 1: So he's pointing out how one of the features of
Speaker 1: running is that that, like you, you can be off
Speaker 1: balance while you're running, because it's the same way like
Speaker 1: a bicycle works. You know, a bicycle works because you're
Speaker 1: by maintaining speed, you could do this thing that you
Speaker 1: couldn't stay balanced to the lower speed. Yeah. And if
Speaker 1: you're the t rex, ideally that that that herbivore is
Speaker 1: going to break your fall and you're gonna do it
Speaker 1: with mouth wide open. Right. So they also touch on
Speaker 1: the fact that that tool use and manipulation amounts to
Speaker 1: a shortcut and evolution uh quote objects that increase the
Speaker 1: potentialities of its body working like prostheses. Uh Why why
Speaker 1: slowly augment your body over the course of you know,
Speaker 1: long stretches of time when you can do something like
Speaker 1: this within a lifetime be a tool use. So they
Speaker 1: conclude that such an alien, if if we're trying to
Speaker 1: imagine an alien emerging in another world, that it would
Speaker 1: need to have some sort of of locomotion and some
Speaker 1: sort of manipulation organs quote the ladder being best derived
Speaker 1: from locomotion organs like legs, the humanoid layout with two
Speaker 1: arms and two legs seems to be optimal. This is
Speaker 1: an interesting point. Yeah, I would I would have maybe said, okay, uh,
Speaker 1: who knows how many legs an alien we encounter might have,
Speaker 1: but if it's moving around on the land, I think
Speaker 1: this is some pretty solid reasoning. There tends to be
Speaker 1: evolution toward fewer numbers of legs over time for to
Speaker 1: increase speed, and that this can free up other limbs
Speaker 1: for tool use, which seems to be an important part
Speaker 1: of tool using intelligence. Like you, you wouldn't need tool
Speaker 1: using intelligence if you didn't have hands to use tools with, right, Yeah,
Speaker 1: it's it's it's an interesting paper. I'm sure there's some
Speaker 1: there's some astrobiologists and biologists that might evolutionary biologist that
Speaker 1: may take issue with this, but but I think I
Speaker 1: think the author makes an interesting argument here. And it
Speaker 1: also as much as I love multi legged aliens in
Speaker 1: my sci fi, it also gives me a little support
Speaker 1: for visions of bipedal aliens being the dominant UH form
Speaker 1: in so many different science fiction visions. Now, this also
Speaker 1: makes me question what unexamined assumptions are we bringing on
Speaker 1: void that could be clouding our vision Right here, we're
Speaker 1: we're thinking, Okay, I'm just trying to universalize about like
Speaker 1: the physics of planets and the principles of evolution and
Speaker 1: not be you know, Earth chauvinist. But but I bet
Speaker 1: there are ways that that we're somehow being Earth chauvinists
Speaker 1: that we're not noticing. Yeah, and I we haven't even
Speaker 1: talked about tales. I can easily imagine some sort of
Speaker 1: an alien creature with a prehensile tail um or you know,
Speaker 1: some other prehensile uh that if they're an animate that
Speaker 1: they're able to use for tool use and manipulation. Well,
Speaker 1: to bring it back to the t rex is, I
Speaker 1: think we did mention this, but despite the fact that
Speaker 1: we don't have tales, tales often form an extremely important
Speaker 1: part of bipedal locomotion. The tails are there to counter
Speaker 1: as a counterweight for the front of the body. If
Speaker 1: you've only got two legs and you're like a t rex,
Speaker 1: you're leading forward. You know, you saw these old pictures
Speaker 1: where people used to illustrate t rex is with their
Speaker 1: tail is dragging on the ground. That doesn't make any
Speaker 1: sense that they of course had to have their tails
Speaker 1: up in the air as a counterweight to the body
Speaker 1: so they could move. Yeah. I am also reminded of kangaroos,
Speaker 1: who have you know, engage in bipedal gates and their
Speaker 1: tails is often utilized as a is a third limb.
Speaker 1: So yeah, there's a whole bunch that we could do there.
Speaker 1: I also have to say there's a whole episode we
Speaker 1: should probably record on just bipedal robots and the attempt
Speaker 1: to create functional bipedal robots, and perhaps getting into the
Speaker 1: idea of why we want to do it as well,
Speaker 1: because they've got to be like us, gotta be like us.
Speaker 1: We got to create a mechanical man. So we'll will
Speaker 1: inevitably come back to that topic in a future episode,
Speaker 1: but for now, there you have it. Bipedalism something we do,
Speaker 1: something other organisms do, something organisms have been doing on
Speaker 1: this planet for a very long time, and conceivably there
Speaker 1: could be other bipeds out there in the universe doing
Speaker 1: their thing as well. Now, if you want to check
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