WEBVTT - The Alien Biped 0:00:03.040 --> 0:00:05.840 Welcome to Stuff to Blow your Mind from how Stuff 0:00:05.840 --> 0:00:14.160 Works dot com. Hey you welcome to Stuff to Blow 0:00:14.200 --> 0:00:17.160 your mind. My name is Robert Lamb and I'm Joe McCormick. 0:00:17.640 --> 0:00:22.680 And today we're talking about bipeds, bipedalism. Uh. And this 0:00:22.760 --> 0:00:25.000 is a this is a topic that I was just 0:00:25.079 --> 0:00:27.840 kind of rattling around my brain the other day because 0:00:28.440 --> 0:00:31.400 for most of us, walking is just kind of every day, right, 0:00:31.440 --> 0:00:33.839 you run a little bit, uh, maybe you hop a 0:00:33.920 --> 0:00:36.640 little bit. It's of course involved multiple times and mammals. 0:00:36.680 --> 0:00:40.440 You have macropods, kangaroo rats in my spring hair hopping, 0:00:40.440 --> 0:00:43.480 my pangolins, and of course homing a apes um much 0:00:44.200 --> 0:00:47.519 which includes ourselves and sometimes scientists, you know, make the 0:00:47.560 --> 0:00:51.920 distinction between facultative and obligate bypeds, though this isn't a 0:00:52.080 --> 0:00:55.600 standard distinction, suffice to say they're creatures such as the 0:00:55.680 --> 0:00:59.600 human flightless birds, and to draw on a prehistoric example, 0:00:59.680 --> 0:01:02.720 the t w rex, that have no real alternative to 0:01:02.840 --> 0:01:06.720 bipedal movement. I mean, I can crab walk around, Yeah, 0:01:06.760 --> 0:01:09.120 I wouldn't. If if you're crab walking, you're still bipedal 0:01:09.360 --> 0:01:12.000 unless you can grow some crab legs. It depends which 0:01:12.080 --> 0:01:13.479 version of the crab walk. Are you're talking, you're talking 0:01:13.480 --> 0:01:15.720 about where you're I'm talking where you know, you lean 0:01:15.840 --> 0:01:17.880 back and you go on all four your belly up 0:01:17.920 --> 0:01:20.040 in the air. Because there's also the Zoidberg walk, where 0:01:20.080 --> 0:01:23.080 you walk from side to side. That's a good one, 0:01:23.120 --> 0:01:25.759 but that's not that that would just be bi Zoidberg 0:01:25.840 --> 0:01:28.160 is a biped No no, no, no, I mean the 0:01:28.160 --> 0:01:30.560 the Exorcist down the stairs. Well oh yes, yes, okay, 0:01:30.560 --> 0:01:34.200 well that that would count, but I fully grant you 0:01:34.319 --> 0:01:36.679 I probably wouldn't get around very quickly doing that all 0:01:36.680 --> 0:01:41.479 the time. Other creatures, of course, are capable of bipedal locomotion, 0:01:41.560 --> 0:01:45.160 but only employed under certain circumstances, like, for instance, a 0:01:45.240 --> 0:01:48.640 lemur dancing you know, sort of prancing sideways across a 0:01:48.720 --> 0:01:53.440 clearing between two trees, a giant ground sloth in in 0:01:53.680 --> 0:01:56.720 in old and olden days, rising up to reach higher branches, 0:01:56.800 --> 0:01:59.120 or or one of my favorites, a cat standing on 0:01:59.200 --> 0:02:02.160 its hind lay eggs to better view pray or something 0:02:02.200 --> 0:02:05.320 of interest. This is always a creepy, weird side if 0:02:05.320 --> 0:02:08.160 you're lucky enough to witness it. Oh but it also 0:02:08.240 --> 0:02:11.440 can be very cute when dogs stand on two legs 0:02:11.480 --> 0:02:13.480 to to get up there closer to the treat that 0:02:13.520 --> 0:02:17.240 they want. Oh, yeah, it's adorable. It's yeah. When dogs 0:02:17.280 --> 0:02:19.160 do it, it's adorable. When cats do it, it is 0:02:19.400 --> 0:02:22.400 it's a little unsettling, like they've suddenly become tiny people, 0:02:22.480 --> 0:02:25.840 like they've been people all along, um or that's my 0:02:25.880 --> 0:02:28.800 read on it. Now. When it comes to the hominans, 0:02:28.960 --> 0:02:33.200 which again includes humans, the oldest evidence of bipedal movement 0:02:33.240 --> 0:02:36.680 in a hominant species was probably six million years ago. 0:02:36.760 --> 0:02:39.760 This would have been the selmthropists, and there's some dispute 0:02:39.800 --> 0:02:42.040 over this, but any rate, we were mostly bipedal by 0:02:42.160 --> 0:02:45.239 say four million years ago. We had a curved spine 0:02:45.280 --> 0:02:48.160 by two point five million years ago, and it altered 0:02:48.160 --> 0:02:51.880 our hip support by one point nine five million years ago, 0:02:52.600 --> 0:02:55.560 and we were fully bipedal by the time of Fomo erectus, 0:02:55.680 --> 0:02:59.120 with signature pelvis and thigh bones evident in the fossil record. 0:02:59.440 --> 0:03:03.160 The legs lengthened over time, allowing for longer strides everything 0:03:03.200 --> 0:03:05.440 that would enable the ministry of silly walks to do 0:03:05.520 --> 0:03:08.239 its thing. Yeah. Now, some of what we know about 0:03:08.520 --> 0:03:11.799 the posture and gate of our ancient ancestors and their 0:03:11.800 --> 0:03:15.080 close relatives has to be inferred indirectly. I mean, you 0:03:15.080 --> 0:03:16.919 can get a pretty good idea from like the shapes 0:03:16.960 --> 0:03:19.320 of bones and stuff that that will tell you a lot. 0:03:19.840 --> 0:03:22.919 There's other there's other evidence that's very direct. A great 0:03:22.960 --> 0:03:26.680 piece of early direct evidence for bipedality is the fossil 0:03:26.720 --> 0:03:30.480 formation known as the Late Totally Footprints. So, Robert, have 0:03:30.560 --> 0:03:32.720 you have you seen what these look like? I think 0:03:32.800 --> 0:03:36.720 I have everybody very cool in In nineteen seventy six 0:03:37.080 --> 0:03:40.200 there was a team working with the paleontologist Mary Leaky, 0:03:40.240 --> 0:03:44.080 and they discovered a collection of fossilized animal tracks in 0:03:44.200 --> 0:03:47.480 late Totally Tanzania, which is south of the Old Duvai Gorge. 0:03:47.920 --> 0:03:50.720 And the tracks were preserved in what had been a 0:03:50.800 --> 0:03:54.640 soft bed of volcanic ash about three point six million 0:03:54.720 --> 0:03:57.440 years ago or three point three point six three point 0:03:57.480 --> 0:04:01.120 seven uh and it had hardened and been preserved for 0:04:01.200 --> 0:04:04.000 us to discover in the twentieth century. And then so 0:04:04.120 --> 0:04:07.000 after these tracks were initially discovered, in nineteen seventy eight, 0:04:07.000 --> 0:04:10.480 Paul Able, a colleague of Leaky's, discovered that the formation 0:04:10.560 --> 0:04:14.000 also contained a twenty seven meter or about eighty eight 0:04:14.000 --> 0:04:18.080 foot long trail of ancient hominin footprints in addition to 0:04:18.160 --> 0:04:22.680 the other animal footprints, probably made by Australian Epithecus afarensis, 0:04:22.839 --> 0:04:25.919 the species to which Lucy belonged, And there were about 0:04:26.040 --> 0:04:29.640 seventy hominin footprints at all in all in this formation. 0:04:30.160 --> 0:04:32.560 And so the thing about these footprints is they're quite 0:04:32.640 --> 0:04:35.960 clearly bipedal. You know, you're not seeing four legged movement, 0:04:36.000 --> 0:04:39.039 and somebody was just walking on two feet through this 0:04:39.160 --> 0:04:43.000 volcanic ash. The prints i've read are space close together, 0:04:43.080 --> 0:04:46.440 meaning a short stride might mean short legs. And the 0:04:46.480 --> 0:04:49.359 prints also show a big toe in line with the 0:04:49.400 --> 0:04:51.760 foot rather than opposed to the foot, as you see 0:04:51.800 --> 0:04:54.920 in arboreal apes. So like you know, your human big 0:04:54.960 --> 0:04:57.640 toes go straight out, the arboreal apes have more kind 0:04:57.640 --> 0:05:00.600 of a toe thumb, like a big toe thumb, uh, 0:05:00.600 --> 0:05:03.320 that they used to climb trees and grab hold of stuff. 0:05:03.800 --> 0:05:06.880 And also their footfalls apparently went heel toe, just like 0:05:06.920 --> 0:05:09.960 ours tend to. So by about three point six million 0:05:10.000 --> 0:05:12.760 years ago, we we've got direct evidence that our ancestors 0:05:12.760 --> 0:05:16.200 and their close relatives were walking on two feet. Uh. 0:05:16.279 --> 0:05:19.080 And I also can't help but mention I've read supposedly 0:05:19.120 --> 0:05:22.120 there's this story of how the prints were discovered because 0:05:22.160 --> 0:05:26.120 one of Leaky's colleagues, a paleo anthropologist named Andrew hill Uh, 0:05:26.240 --> 0:05:29.599 stumbled across the fossil formation when he and another colleague 0:05:29.600 --> 0:05:34.159 were running around throwing elephant poop at each other. Oh well, 0:05:34.560 --> 0:05:38.839 you know you gotta keep it lighthearted on the dick, right, So, um, 0:05:39.040 --> 0:05:41.320 like you said, we we know all of this based 0:05:41.400 --> 0:05:44.400 on mostly fossil remains, and by that this, you know, 0:05:44.400 --> 0:05:46.760 we're looking at the bones of our ancestors and observing 0:05:47.080 --> 0:05:50.520 what the gradual shift to bipedalism did to us. And 0:05:50.560 --> 0:05:53.359 it certainly certainly came at a cost. Yeah, now, to 0:05:53.400 --> 0:05:55.679 be sure it was it was worth it, I guess. 0:05:55.680 --> 0:05:57.479 I mean. It made it easier for us to pick 0:05:57.560 --> 0:06:00.440 up fruits and pick up pick from a low line branches. 0:06:00.480 --> 0:06:04.040 It gave us free hands for carrying food and also 0:06:04.160 --> 0:06:08.080 very importantly carrying tools, carrying our young as well. It 0:06:08.160 --> 0:06:11.000 allowed us to rise up and appear larger and more 0:06:11.120 --> 0:06:14.520 fearsome to our enemies. Are many enemies of the wild. 0:06:14.600 --> 0:06:16.640 This is something that I think we often don't think about. 0:06:16.760 --> 0:06:19.160 But unless you're being instructed on how to react to 0:06:19.200 --> 0:06:22.040 a bear in the win the wild, you know, they say, 0:06:22.080 --> 0:06:24.560 make yourself as big as possible, and certainly there are 0:06:24.560 --> 0:06:28.600 other animals that do just the same thing, but that's 0:06:28.640 --> 0:06:30.520 one of the strengths of being able to at least 0:06:30.600 --> 0:06:32.960 rise up on two feet. Yeah, now you can't know 0:06:33.040 --> 0:06:37.719 this for sure, but I tend to think that bipedalism 0:06:37.920 --> 0:06:43.320 is a sort of necessary precursor to advanced tool using intelligence. 0:06:43.360 --> 0:06:47.400 I mean, you see some use of tools in quadrupedal apes, 0:06:48.040 --> 0:06:50.680 but the fact that the fact that you're walking on 0:06:50.760 --> 0:06:54.760 two feet gives you free hands, and having free hands, 0:06:54.880 --> 0:06:57.760 it seems like suddenly you've got much more incentive to 0:06:57.839 --> 0:07:01.400 be using them for all kinds of stuff. Well, it's 0:07:01.440 --> 0:07:03.679 interesting when you think about the animals that do display 0:07:03.680 --> 0:07:05.440 some form of tool use. I mean, certainly you have 0:07:05.520 --> 0:07:08.480 the the apes, which are going to more or less 0:07:08.520 --> 0:07:10.320 aligned with the human experience of tool use. But then 0:07:10.360 --> 0:07:12.880 of course you have like the corvids uh and uh 0:07:12.920 --> 0:07:16.760 and a few other birds that that also use tools. Now, 0:07:16.760 --> 0:07:21.600 obviously they are engaging in bipedal ground movement. Their wings 0:07:21.600 --> 0:07:26.920 are tucked away, but it's perhaps and it's a slightly 0:07:26.920 --> 0:07:30.320 different situation with birds because those wings do have a purpose. Uh, 0:07:30.400 --> 0:07:33.960 They've just specialized their their their beak functionality, and I've 0:07:34.040 --> 0:07:36.440 learned how to use tools with that. The same is 0:07:36.440 --> 0:07:38.480 truy of dolphins. You know they're using when they engage 0:07:38.480 --> 0:07:42.480 in tool use, are using their snout um octopi slightly 0:07:42.480 --> 0:07:45.640 different situation they have they have They have a wide 0:07:45.720 --> 0:07:49.760 variety of limbs and are not necessarily gonna become bipedal 0:07:49.800 --> 0:07:52.320 anytime soon. So anyway you shake it the back to 0:07:52.360 --> 0:07:55.080 the human scenario, it helped us expand our range. It 0:07:55.240 --> 0:07:58.920 It definitely played a part in our our ascension or dominance, 0:07:59.200 --> 0:08:02.400 certainly our ability to invent things and expand, but we 0:08:02.480 --> 0:08:05.840 also paid a price. We had to distribute all of 0:08:05.840 --> 0:08:08.360 our weights on two limbs, resulting in all sorts of 0:08:08.360 --> 0:08:11.840 painful experiences such as a lower back pain, slip discs, 0:08:12.200 --> 0:08:16.520 arthritis in the lower body, fallen arches. Our spines are 0:08:16.640 --> 0:08:20.120 ultimately just kind of weird. We evolved wider hips and 0:08:20.160 --> 0:08:22.040 stronger knees to kind of cope with it to a 0:08:22.040 --> 0:08:25.800 certain extent. But this is the reason that roughly of 0:08:25.840 --> 0:08:28.960 adult humans will experience back pain in their lives. I 0:08:28.960 --> 0:08:31.760 would say one of the biggest anatomical drawbacks is that 0:08:31.800 --> 0:08:34.400 we can make finger guns at each other. I mean 0:08:34.440 --> 0:08:38.360 that that is a true blow to the species you mean, 0:08:38.400 --> 0:08:41.240 I mean the beneficial kind where like kids playing cowboys 0:08:41.240 --> 0:08:43.960 and Indians or whatever on the playground, know the like 0:08:44.040 --> 0:08:48.640 the like catch you later, bro Okay. So also it 0:08:48.679 --> 0:08:51.559 also affected the way that we give birth and uh 0:08:51.600 --> 0:08:53.160 and this is a I have to say, this is 0:08:53.160 --> 0:08:56.000 a topic that we could easily have devoted an entire episode. 0:08:56.200 --> 0:09:00.720 There's a lot of scholarship and debate on exactly how 0:09:00.760 --> 0:09:07.440 the modern human birthing scenario pans out towards prehistoric examples, 0:09:07.480 --> 0:09:10.640 but the move towards the bipedal form changed our skeletons. 0:09:10.679 --> 0:09:13.880 This affected the pelvis. Most primates have a pretty straight 0:09:13.960 --> 0:09:17.640 birth canal, but hominans soon boasted a narrow, distorted, kind 0:09:17.640 --> 0:09:20.760 of fun house tube of a birth canal. The offspring 0:09:20.760 --> 0:09:22.800 had to twist and turn in order to pass through. 0:09:23.200 --> 0:09:26.400 This is true of our our ancestors. But our bodies 0:09:26.440 --> 0:09:29.760 continued to evolve. We became taller, we grew larger brains. 0:09:29.880 --> 0:09:32.760 That means meant bigger brained babies having to make it 0:09:32.840 --> 0:09:37.720 through that twisting tunnel. Everything became tighter. Child birth became 0:09:37.760 --> 0:09:41.520 a potentially more dangerous affair, because it also means giving 0:09:41.559 --> 0:09:44.120 birth to a child an earlier stage of its development 0:09:44.120 --> 0:09:46.760 in order to actually break it free from the confines 0:09:47.080 --> 0:09:50.520 of our bipedally twisted bodies. Now, again, there's a lot 0:09:50.520 --> 0:09:52.680 more to this. Scientists have gone back and forth on 0:09:52.720 --> 0:09:57.679 the so called obstetric dilemma, but bipedal evolution certainly changed things. 0:09:58.320 --> 0:09:59.840 All right, I think we should take a quick break. 0:10:00.000 --> 0:10:03.120 We will be right back to discuss why bipedalism evolved 0:10:03.120 --> 0:10:08.959 in humans. Thank alright, we're back. So this is a 0:10:09.000 --> 0:10:11.040 big question because certainly we can point to all of 0:10:11.080 --> 0:10:14.240 these like the pros and all the cons, but like, 0:10:14.280 --> 0:10:17.439 what is the driving force right right now? What caused 0:10:17.640 --> 0:10:22.559 our our ancient hominin ancestors to go on two legs? Primarily, 0:10:22.679 --> 0:10:25.240 why did our ancestors become bipetle And this is an 0:10:25.240 --> 0:10:29.440 ongoing debate. We know at some point we transitioned from 0:10:29.480 --> 0:10:32.680 mostly four footed gate to a mostly two footed gate, 0:10:32.720 --> 0:10:34.920 but why did it happen and what type of pressure 0:10:35.000 --> 0:10:38.760 selected for this? So, first of all, when answering questions 0:10:38.800 --> 0:10:41.080 like this, it's often hard to be certain, right, you know, 0:10:41.120 --> 0:10:44.800 we only have the evidence we can find. Fossil evidence helps, 0:10:44.840 --> 0:10:47.880 but it's hard to like run new experiments to test this. 0:10:48.000 --> 0:10:50.120 We you know, we only have the fossil finds we 0:10:50.200 --> 0:10:53.240 have and can only draw the conclusions we can draw 0:10:53.280 --> 0:10:56.320 from them. And there have been all kinds of answers 0:10:56.320 --> 0:10:59.800 over the years. So for a long time, consensus seem 0:10:59.840 --> 0:11:03.800 to be that bipedalism was an adaptation to a change 0:11:03.840 --> 0:11:08.160 in our primary habitat, as our ancestors moved down out 0:11:08.160 --> 0:11:12.199 of the trees into a flat grassland, perhaps driven by 0:11:12.360 --> 0:11:16.320 changing climate, like changing climate killed off forests and left 0:11:16.400 --> 0:11:19.199 these you know, savannahs with tall grasses in their place, 0:11:20.200 --> 0:11:22.839 or these creatures just moved down into the savannahs to 0:11:22.880 --> 0:11:26.160 follow food sources or something. In this case, uh, these 0:11:26.160 --> 0:11:30.400 hominins needed to stand up to see over the tall grass. 0:11:30.440 --> 0:11:33.560 And this explanation is not still favored. This has fallen 0:11:33.600 --> 0:11:36.520 out of favor among experts, and one reason is that 0:11:36.880 --> 0:11:41.079 climate history analysis and physical fossil evidence indicate that we 0:11:41.080 --> 0:11:44.360 were becoming bipedal at the same time that we were 0:11:44.400 --> 0:11:48.160 still adapted to climbing and living in trees. And I 0:11:48.160 --> 0:11:50.439 think there are multiple lines of evidence supporting this. It 0:11:50.720 --> 0:11:54.560 appears that at some point our ancestors were both like 0:11:54.800 --> 0:11:58.200 living in forests and climbing trees, but also having skeletons. 0:11:58.320 --> 0:12:02.920 That's supported bipedal walking gate. Also, it's worth pointing out 0:12:03.000 --> 0:12:07.000 that plenty of other animals that occupy areas with tall 0:12:07.040 --> 0:12:11.319 grasses tall grasslands do just find staying on all fours right. 0:12:11.679 --> 0:12:13.920 They don't need to stand up to see over the 0:12:13.960 --> 0:12:18.000 grass in order to survive. Like grassland baboons today are 0:12:18.000 --> 0:12:20.920 still quadrupedal. So that used to be what people thought, 0:12:21.000 --> 0:12:25.079 but that is not no longer the main hypothesis. So 0:12:25.320 --> 0:12:28.160 another theory that is popular with the public but not 0:12:28.320 --> 0:12:32.480 with scientists in the relevant fields is the much much 0:12:32.520 --> 0:12:35.640 beloved aquatic ape theory. Oh yes, we talked about this 0:12:35.800 --> 0:12:39.520 um last year. Yeah, and our Aquatic Humanoids episode. We 0:12:39.600 --> 0:12:42.360 concluded that there's not really any good evidence for this. 0:12:42.480 --> 0:12:46.520 There's no direct fossil evidence for whatsoever. And the indirect 0:12:46.600 --> 0:12:49.440 reasoning that causes people to think that there's evidence for 0:12:49.480 --> 0:12:52.559 this is, uh, it's just not very good. But we 0:12:52.600 --> 0:12:54.679 should mention it because this is bound to come up 0:12:54.679 --> 0:12:58.280 whenever people address bipedality in its origins. I think it's 0:12:58.320 --> 0:13:01.160 just because it's fun to imagine, maybe, and because it's 0:13:01.200 --> 0:13:04.960 unconventional that makes it more interesting to people. Basically, it 0:13:05.040 --> 0:13:09.320 says that the explanation for the main phenotypic variations between 0:13:09.440 --> 0:13:12.320 us and our closest ape relatives is that our direct 0:13:12.360 --> 0:13:17.120 ancestors briefly evolved to become water dwelling primates so sort 0:13:17.160 --> 0:13:21.320 of like fishmen and uh, and then moved back to 0:13:21.440 --> 0:13:25.200 dry land after that. And under this theory, bipedality evolves 0:13:25.320 --> 0:13:28.320 because we need to keep our heads above water when 0:13:28.360 --> 0:13:32.000 we're waiting around in search of shellfish for food. All Right, 0:13:32.280 --> 0:13:33.960 it would be kind of like the idea that that 0:13:34.040 --> 0:13:36.640 we became bipedal because we didn't want to get our 0:13:36.679 --> 0:13:41.680 t shirts wet, you know, I mean, it's it's not 0:13:41.800 --> 0:13:44.760 that bad, but yeah. So this was first proposed by 0:13:44.800 --> 0:13:48.040 Alistair Hardy, and it was mainly developed by somebody named 0:13:48.040 --> 0:13:52.320 Elaine Morgan. And in short, Morgan says, look, we're the 0:13:52.360 --> 0:13:55.760 only mammal that consistently walks on two legs, but some 0:13:55.880 --> 0:13:58.920 four legged animals can occasionally stand up on two legs 0:13:59.280 --> 0:14:02.679 and wind. Do our closest stape relatives walk on two legs? Well? 0:14:02.720 --> 0:14:05.720 She claims there's only one circumstance when they always walk 0:14:05.800 --> 0:14:08.080 on two legs, and that's when they're waiting in water. 0:14:08.679 --> 0:14:12.400 I see some pretty clear evidence running counter to this assertion, 0:14:12.760 --> 0:14:17.200 just in publicly available video like primates. You look this up. 0:14:17.240 --> 0:14:20.280 Primates sometimes stand up on two legs for all kinds 0:14:20.320 --> 0:14:23.480 of reasons while carrying objects and moving around with them 0:14:23.680 --> 0:14:28.120 during dominance displays to reach something like they don't. And 0:14:28.200 --> 0:14:30.800 they also, on top of that, don't always stand up 0:14:30.840 --> 0:14:33.680 when waiting in water. I found video of guerrillas waiting 0:14:33.680 --> 0:14:36.560 around in water, and they tend to stay on all fours. 0:14:36.600 --> 0:14:39.320 So if the classic explanation about seeing over the grass 0:14:39.400 --> 0:14:41.760 is probably wrong and we don't put any stock in 0:14:41.800 --> 0:14:45.680 the aquatic ape, what is the real explanation? Of course, 0:14:45.720 --> 0:14:47.040 we still don't know, but there are a lot of 0:14:47.080 --> 0:14:51.200 competing theories. Maybe there was a selection pressure on having 0:14:51.360 --> 0:14:55.080 free hands, so maybe some of our ancestors began carrying 0:14:55.240 --> 0:14:59.840 or throwing things, and for some reason this got started, 0:15:00.000 --> 0:15:03.119 and then there was a great survival or reproduction advantage 0:15:03.160 --> 0:15:05.760 for the ones that did this more and more of 0:15:05.800 --> 0:15:08.000 the time. So being able this comes back to the 0:15:08.000 --> 0:15:10.120 examples of being able to carry ones young, being able 0:15:10.160 --> 0:15:12.240 to carry food that you've gathered, or being able to 0:15:12.280 --> 0:15:14.680 carry a tool or a weapon, say a nice you 0:15:14.720 --> 0:15:18.200 know jaw bone for smacking the other epe creatures around. Well, 0:15:18.360 --> 0:15:21.760 I mean a big one I've seen suggested actually is throwing, 0:15:22.360 --> 0:15:26.800 Like if if we evolved somehow a throwing hunting strategy 0:15:26.800 --> 0:15:29.800 where you would throw objects, that this could have spurred 0:15:30.080 --> 0:15:33.640 bipedality or some bridge to it. Another thing I was 0:15:33.680 --> 0:15:36.560 reading about in a BBC article is that recent research 0:15:36.600 --> 0:15:41.560 has suggested that perhaps partial bipedality helped these hominins adapt 0:15:41.600 --> 0:15:46.720 to rocky, uneven terrain in geologically active areas. Essentially that 0:15:46.760 --> 0:15:50.200 our ancestors were not only tree climbers, but rock climbers, 0:15:50.560 --> 0:15:52.920 and this encouraged them to take on some traits that 0:15:53.000 --> 0:15:57.800 bridge the gap to bipedalism. Another is, I guess sort 0:15:57.840 --> 0:16:01.240 of the least the least interesting is an idea but 0:16:01.360 --> 0:16:03.400 has seems to have a lot going for it, And 0:16:03.440 --> 0:16:06.800 it's simply that a certain kind of bipedalism in tree 0:16:06.880 --> 0:16:11.400 dwelling life became useful, as it is in many orangutans today. 0:16:11.440 --> 0:16:14.320 Like you can look at orangutans living in the trees 0:16:15.120 --> 0:16:17.640 that walk around on two feet, like they'll reach up 0:16:17.680 --> 0:16:20.680 and grab branches with their arms over their heads while 0:16:20.720 --> 0:16:23.280 walking around on other branches with two feet, it's just 0:16:23.320 --> 0:16:26.000 a great way to anchor yourself between a lower and 0:16:26.280 --> 0:16:29.120 upper branch. So there are a lot of competing theories. 0:16:29.200 --> 0:16:30.880 I mean, I know there are other ones we didn't 0:16:30.920 --> 0:16:33.600 even cover here, but this is this is an unsolved question. 0:16:33.640 --> 0:16:36.520 We still don't know the answer now anyway to shake it. 0:16:36.840 --> 0:16:41.480 We were not the first bipeds, not even close. I 0:16:41.480 --> 0:16:44.280 already mentioned the t rex, you know that, that famous 0:16:44.320 --> 0:16:48.600 the famous Cretaceous period, the carnivore Cretaceous spirit, of course, 0:16:48.640 --> 0:16:51.440 banned hundred forty five million years ago to sixty six 0:16:51.440 --> 0:16:54.520 million years ago. And this again, it's just an animal 0:16:54.560 --> 0:16:58.000 that could scarcely be more of a biped you know, 0:16:58.160 --> 0:17:01.400 those tiny little arms. And of course he or she 0:17:01.560 --> 0:17:04.040 is just one of the many therapods that roamed the 0:17:04.040 --> 0:17:07.359 prehistoric Earth, and in many cases not not not just 0:17:07.960 --> 0:17:11.880 roamed it, but ran after their prey, running a key 0:17:11.920 --> 0:17:16.960 advantage of their bipedal morphology. But even they, it seems 0:17:17.000 --> 0:17:19.919 we're not the first. Um there's a two hundred and 0:17:20.040 --> 0:17:23.320 ninety million year old fossil of a species that is 0:17:23.400 --> 0:17:28.480 dubbed ood Obama's Kersaurus. This is a creature that was 0:17:28.800 --> 0:17:32.440 very lizard like it seems, and it's a probable appearance, 0:17:32.760 --> 0:17:36.560 had short fore limbs, relatively long tail and high and 0:17:36.880 --> 0:17:39.800 also relatively long hind limbs. So these are kind of 0:17:39.800 --> 0:17:43.160 the hallmarks of of a bipedal creature. But the other 0:17:43.200 --> 0:17:44.879 curious thing about it is that it seems to have 0:17:44.920 --> 0:17:47.440 been a herbivore rather than a meat eat or like 0:17:47.640 --> 0:17:51.840 the theropods. Therefore it probably palin. I just think it 0:17:51.880 --> 0:17:56.520 probably depended on bipedal running to flee from quadrupedal danger. 0:17:57.359 --> 0:18:01.920 And on the subject of dinosaurs and quadrupedal and bipedal arrangement, 0:18:02.200 --> 0:18:06.000 I found a two thousand five article in Astrobiology magazine 0:18:06.560 --> 0:18:10.919 that brings up a species that is dubbed Masso spondulous. 0:18:11.240 --> 0:18:15.119 And this is a pro sorrow pod now Sara pods 0:18:15.160 --> 0:18:19.040 as everyone remember that. You know, they're the giant Diplodocus 0:18:19.520 --> 0:18:24.280 Brachiosaurus style kind of creatures, you know, big, enormous quadrupeds. 0:18:24.280 --> 0:18:30.640 It just enormous, just ponderous creatures. The pro sauropods, unlike 0:18:30.760 --> 0:18:34.600 their descendants, they could rise up on their hind legs 0:18:34.680 --> 0:18:38.040 and go after food bi petally. So back in two 0:18:38.080 --> 0:18:43.080 thousand five, University of Toronto at Mississaugua thiss ut M 0:18:43.160 --> 0:18:46.719 biology professor Robert Rice. He looked at an embryo of 0:18:46.760 --> 0:18:50.920 one of these massospondulous creatures and he found the thing 0:18:51.040 --> 0:18:53.200 was that it looked like a four legged saara pod. 0:18:53.800 --> 0:18:57.480 So he hypothesized that it would have grown into a 0:18:57.560 --> 0:19:01.159 full bipedal form as it matured. Uh this is what 0:19:01.200 --> 0:19:05.480 he told Astro Astrobiology magazine quote. Because the embryo of 0:19:05.560 --> 0:19:09.719 massospondos looks like a tiny saua pod with massive limbs 0:19:09.720 --> 0:19:12.520 in a quadrupedal gait. We proposed in our paper that 0:19:12.560 --> 0:19:17.560 the sauropods gate probably evolved through a phenomenon called ptomorphosis, 0:19:18.040 --> 0:19:21.560 the retention of embryonic and juvenile features in the adult. 0:19:22.520 --> 0:19:25.000 So this is interesting cause we're talking about a creature 0:19:25.080 --> 0:19:30.760 that potentially adapted bipedal, the bipedal gate, but then left 0:19:30.800 --> 0:19:35.199 it behind. Uh paedomor morphosis. By the way, it's it's 0:19:35.240 --> 0:19:38.479 something we see today in various amphibian speeches species. But 0:19:38.560 --> 0:19:41.560 for for these saua pods and for the true sauropods, 0:19:41.600 --> 0:19:44.480 it would mean that they were essentially man babies of 0:19:44.520 --> 0:19:47.440 the prehistoric world, like they simply no longer had to 0:19:47.480 --> 0:19:50.639 grow up like they were the biggest forest eating dumpsters 0:19:50.680 --> 0:19:53.840 on the planet, and therefore they really didn't have to 0:19:53.960 --> 0:19:57.560 augment their more or less larval form anymore. You know, 0:19:57.680 --> 0:20:02.240 I have often wondered something when looking at bipedal therapod 0:20:02.320 --> 0:20:06.200 dinosaurs like the t rex. Just look at that powerful 0:20:06.280 --> 0:20:10.040 lower body and then the tiny little baby arms out front. 0:20:10.840 --> 0:20:14.359 If this dinosaur fell down or even just you know, 0:20:14.400 --> 0:20:16.320 went to have a little lie down in the meadow, 0:20:16.880 --> 0:20:19.840 how did it get back up. I'm not saying it 0:20:19.880 --> 0:20:23.760 would be impossible, it just seems very awkward. Of course, 0:20:23.800 --> 0:20:25.960 we're by peedle and we can get up from the ground, 0:20:25.960 --> 0:20:28.679 but we have long arms and strong upper bodies to 0:20:28.720 --> 0:20:31.840 help us. Try lying down on the ground and then 0:20:31.920 --> 0:20:34.600 getting up without using your arms at all. You can 0:20:34.680 --> 0:20:37.240 probably do it, but it's not so easy, is it? 0:20:37.960 --> 0:20:40.640 And the t rex probably has an even lower relative 0:20:40.640 --> 0:20:43.960 center of mass than you. So what's going on? Like, 0:20:44.480 --> 0:20:46.280 was it this much of a struggle for the t 0:20:46.440 --> 0:20:48.800 rex every time it had to get up from the ground. 0:20:49.040 --> 0:20:51.920 That's a great question. Well, I've been wondering this for 0:20:51.960 --> 0:20:54.600 a while. I finally looked it up. There's actually a 0:20:54.640 --> 0:20:57.720 really good explainer on this in Scientific American provided by 0:20:57.760 --> 0:21:01.719 the paleontologist Gregory M. Ericson of Florida State University. And 0:21:01.760 --> 0:21:04.000 so here's what Erickson says. First of all, there has 0:21:04.320 --> 0:21:07.879 long been a dispute over exactly what the t rex 0:21:07.960 --> 0:21:11.399 is tiny four limbs were four uh maybe you know. 0:21:11.480 --> 0:21:13.880 One idea says, maybe they're just a vestigial, meaning they're 0:21:13.880 --> 0:21:16.159 actually not good for much of anything at all, and 0:21:16.200 --> 0:21:19.399 they only existed in diminished form because the rex hadn't 0:21:19.440 --> 0:21:23.320 fully lost them yet. And then the next idea says, well, 0:21:23.359 --> 0:21:27.679 maybe they're grasping arms used in copulation. And then the 0:21:27.720 --> 0:21:30.119 next idea says, maybe there's some sort of meat hook 0:21:30.320 --> 0:21:33.399 for feeding chunks of flesh into the mouth. Though this 0:21:33.480 --> 0:21:36.080 hypothesis was beaten down when it became clear that the 0:21:36.200 --> 0:21:38.800 arms of a t rex could not reach its mouth. Yeah, 0:21:39.080 --> 0:21:40.640 this is one of those things that when we went 0:21:40.640 --> 0:21:44.120 to the museum in Chicago, the Field Museum, that became obvious. 0:21:44.359 --> 0:21:46.520 You can when you go up to the arm, Uh, 0:21:46.960 --> 0:21:50.200 the fossil bones of the t rex's arm, they are 0:21:50.200 --> 0:21:53.119 the size of my arm. But the t rex is 0:21:53.160 --> 0:21:55.840 the size of like a two story house. And uh, 0:21:56.760 --> 0:22:01.440 clearly this is a shrunken limb exactly. But another hypothesis 0:22:01.960 --> 0:22:06.360 is that the baby arms were useful exactly for helping 0:22:06.400 --> 0:22:08.400 the t rex get back up when it was lying 0:22:08.440 --> 0:22:10.840 on the ground. So in the year nine seventy, the 0:22:10.880 --> 0:22:15.400 British paleontologist Barney Newman speculated that maybe the arms could 0:22:15.400 --> 0:22:17.240 help the t rex do a do a thing kind 0:22:17.240 --> 0:22:19.160 of like a push up. It would be a push 0:22:19.240 --> 0:22:21.800 up motion where the where it would help the rex 0:22:21.880 --> 0:22:25.240 keep from sliding forward along the ground as it tried 0:22:25.280 --> 0:22:28.760 to raise its body to a standing position. Just imagine 0:22:28.760 --> 0:22:31.560 trying to rise without anything to brace you, like lie 0:22:31.560 --> 0:22:34.720 flat on your stomach and then try to push yourself 0:22:34.800 --> 0:22:38.240