00:00.00 Connor Yeah, you are only hope. 00:05.99 Cornpop Oh no is that peak at you. 00:06.42 Connor Oh oh God he's got a helium. Oh my man. 00:12.50 archpodnet Welcome daas so what off 5 of the laugh roads podcast how house carford golffriend her with black girl David doted that cutter ever David Howard cutter joted tonight we under blue our guest stuff had meow was retorting to us for the third time. 00:22.80 Cornpop Ah, wide. 00:31.34 archpodnet On this podcast. Ah we're so excited to have a fun So well, you come back called the book. 00:40.31 Cornpop Ah, all right? You did it man you you got to laugh again. 00:50.85 archpodnet You stefan walked away just walked with. Ah. 00:52.50 Cornpop Um, it's all frozen for me I get but but. 01:06.73 Cornpop Is he just frozen or is he gone. Ah oh no, he's getting one too. Ah. 01:08.44 archpodnet Yeah, no, he got up and left like he legitly walked away from his computer. 01:15.27 Connor And we lost our guest. Oh. 01:18.40 StefanMilosavljevich Um, yeah, a proper glad to be here. Thanks so much. 01:27.39 archpodnet Stuffan that's always a posture to have while the show like really grateful for but with all super pe or do 2 chatts really took it off so under a dad on so on you know at bar with all go with there was always ah treasure tod. 01:31.42 Cornpop The blood. 01:38.79 StefanMilosavljevich Yeah, thanks, oh that that faded really quickly. Yeah, thanks, it's the fifth appearance now on the podcast. 01:45.40 Cornpop He just left the room I thought in Disgust but he came back with the with a bull. Ah oh that is not what I thought about. 01:54.76 archpodnet A. 01:55.80 StefanMilosavljevich That's the perks of having a 2 year old child. There's always helium balloons just lying around left over from various birthdays. 02:00.76 archpodnet Yeah. 02:05.36 Cornpop All right? Well welcome to episode 1 of 5 on welcome to episode 1 of 5 leveragen podcast we're here with stepefan milo ready to talk about human evolution and brain size isn't that right? Carlton oh. 02:18.65 archpodnet Yeah man so ah Stefan you're working on a new ah new video. Well you're probably working on a couple videos. Um and you wanted to chat with us about some of the research material that you're using as it relates to um. 02:24.45 Cornpop You're frozen. 02:34.66 archpodnet Human Brain size. So I guess like just to kind of kick us off and introduce us like ah what are you working on and. 02:39.19 StefanMilosavljevich Yeah, exciting Stuff. Exciting Clickbaity evolutionary stuff for sure. Ah so many of a life in Ruins listeners will probably be aware that over the course of human evolution. Our brain size. Increased a lot like 4 times. Ah but less well known is that recently certainly since like the end of the ice age. It started going the other way it started shrinking again and there are. Basically basically no one's sure why no one's sure if it's affecting our whole brain or just parts of our brain. It's a bit of a genuine mystery. But there are some some different ideas that people have about what might have caused our brains to. Shrink. 03:41.90 StefanMilosavljevich I Can't hear any of you. Oh. 03:43.38 Cornpop Um, my mic was off so that explains why?? Um, so my understanding was that and this might be outdated now. But maybe the audience is familiar with this that like we always hear that neanderthals had bigger brains than Humans. Um. And then like the reason why our brains are smaller is that our brains are more compressed and the wrinkles in the the year eye and the soul guy are more connected so they're faster didn't need to be as big I don't know if that's still a thing or not but that was my understanding. 04:16.85 StefanMilosavljevich I Don't know I don't know I don't even know the parts of the brain that you just mentioned as a yeah video is still in the wrinkles. Yes, yes, the scientific term. Yes, ah what's complicated about. 04:23.90 Cornpop The wrinkles. Yeah. 04:33.55 StefanMilosavljevich Ah, discussing differences in brain size between say neanderthals and homo sapiens is our bodies of different sizes and so neanderthal brains were genuinely bigger than homo sapien brains on average um like um I'm looking at. And neanderthal skull I've got here in my room ah old man of Las chapelll he had a brain shout out. We'll put his Instagram in the description. Um, he had a brain size of sixteen hundred cubic centimeters and the average modern capacity. 04:55.24 Cornpop Shout out Punk clones. 05:09.87 StefanMilosavljevich Ah, least amongst like a european male is like 1400 plus or minus about 100 so his brain would have been about a hundred cubic centimeters bigger than the modern average bigger than the top end of the modern average. But. If. He'd have been a little bit stockier. You know, maybe it's not so um, so drastically bigger but it still probably was a bit bigger. Yeah. 05:33.60 Connor So would be like a ratio like relative brain size compared to body size. That's that'd be a better measure of it kind of comparing those length things. Yeah. 05:40.83 StefanMilosavljevich Yeah, exactly Yeah, there's ah, there's you know some magic formula between body size and brain size. Obviously an Elephant's brain is way bigger than us. But they don't have microwaves so we're winning. 06:01.72 StefanMilosavljevich We're definitely winning the evolutionary Arms race. Um, but yeah, so it's a bit of a mystery. No one's really sure why no one's even sure if this affects the whole world. That's another debate. 06:04.98 Cornpop Um, um. 06:18.79 StefanMilosavljevich About it. It does seem to be extremely widely reported like certainly European Brains have gotten smaller. That's a definite Chinese people. Ah South African People Australians Ah so it does seem to be like this huge geographic span but whether it's truly global. Is ah is also up for debate. 06:42.16 Cornpop Um I had a thought that escaped me. 06:45.77 Connor That's I mean that's I was gonna say so ah to bring it back a little bit farther. So we think there's obviously a braining size increase from like was it like oustro Pith Oustra pull it that word. 06:59.50 archpodnet Australopitha Scenes connor. 07:02.72 Connor Um, on and there are like hypotheses about about why and how that happened so it's and and could you guys like give us a like ah brief summary of of that so we can kind of compare and contrast and see how like these the other factors that are involved in kind of brain size. 07:18.97 archpodnet Well, there seems to be this inverse size like the larger the brain the smaller the gut so like ancestral hominids like the oostrolopithecines early Homo have smaller brains but they have larger guts because a lot of that. 07:21.15 Connor As it changes through time. 07:26.90 Cornpop In. 07:35.72 archpodnet Is believed to have to do it. At some point we start using fire to cook our food which like predigests it so we don't need to spend as much energy on digesting and therefore we can feel larger brains. So there's that whole aspect and like that even is still like a highly debated topic within paleoanthropology is when are we starting with fire and like what's the. Causality for us getting larger brains but there seems to be like as guts get smaller brains get bigger. So that's where the energy is coming from right? So if you imagine a human body like a cpu. It only has 100% at any 1 point and you have to divvy up what programs are using most of the Gpu. So. Looking at humans when you spend less energy on the gut. You can spend more on like your processor or something you know equivalent to whatever the brain is right? So that's that's kind of the idea and the predigesting. Yeah um. 08:23.11 Cornpop Sure So the fire is doing the judge digesting for us. Yeah, okay. 08:33.20 archpodnet So you know like other carnivores right? like they like Lions will gorge. You know they'll eat 1 big meal and like relax for two days and they need another one because like after they eat all that meat. They just like lay around and they have to digest whereas like the ability to cook food. Um. Ah, preprocess it for us so we don't have to spend nearly as long digesting. So and as as Stefan mentioned we see that upward trend of cranial capacity ccs and neanderthals end up having the largest cranial capacity but you know. Neanderthals ended up becoming subsumed into the greater homo sapiens sapien population and we kind of I think goes what neanderthal cranial capacity is about 650 ccs and homo sapiens is about 600 ccs if I'm correct. 09:11.27 Cornpop And they got gentrified. 09:21.83 Cornpop I would not know off the top of my head. But. 09:21.55 StefanMilosavljevich So ah, 1600 yeah Yeah sixteen hundred not six hundred six hundred would be like early Homo Homo habris or something. 09:23.96 archpodnet Cubic centimeters yeah Yeah yeah, sorry I missed ah I missed ah I missed. Ah, my tens one of my tense places. So yeah, so there's cranial capacity and then there's also cubic centimeters both are ccs sorry I kind of talked over myself. But yeah, um, and then so you sent us 2 articles to help maybe explain this or a new trend that we're seeing Stefan that you had mentioned. Um, the first one is the hypotheses for the evolution of reduced reactive aggression in the context of human self-dication by Dr Richard Wringham from the department of human evolutionary biology at Harvard. 10:05.66 Cornpop Oh he's um, chimpanzee guy. He did ranang him at all about the chimpanzee aggression as part of my thesis. Um, people don't like that one. 10:14.44 archpodnet Oh sweet and then we have when and why did human brains decrease in size. A new change point analysis and insights from brain and evolution in ants by dasilva at all 2021 so how did you get on this topic Stefan. 10:29.80 StefanMilosavljevich I I was just just perusing the internet as I do looking for interesting topics that would make great evolution themed Youtube Videos Prehistoric Themed Youtube videos and it's just. Sometimes you just hear an idea and it immediately just starts. You know a chain reaction in your brain. It's just I don't think people who are even pretty familiar with human evolution are aware that our brains have decreased in size. That is really not what we anticipate the trajectory of our evolution to be especially because since this decline has occurred. We've absolutely hit our stride in terms of like technological developments scientific developments cultural developments. Ah there's you know, no sign. That we're declining in intelligence and yet our brains are decreasing and that's that's just that's just interesting I think someone's gonna see that and think it's interesting. So that's what that's what got me started on that on that road and then just sort of picking apart. 11:38.25 Cornpop Yeah, because. 11:46.84 StefanMilosavljevich Try and find different papers see what different experts are saying about this and I am not an expert to any of the listeners this my fifth time on the show. So you already know I'm not an expert but just as just so everyone knows that but I do is fifth time. 11:59.19 Cornpop Um, you're ironically though the oh wow. Ah yeah, you're you're the guy that we call when we're like I don't know Stefan probably does that we just have you on? um. 11:59.35 archpodnet Have you been on 5 times or is this your fifth time huh. 12:04.75 StefanMilosavljevich Think so. 12:15.44 StefanMilosavljevich That's a nice way of putting like damn we didn't book a guest. What's Stefan up to this week 12:20.52 Cornpop Ah, no man but you you know like your stuff like I can't I dabbled in that stuff in college like we all took physical anthropology or biological anthropology but like obviously you're more red up on it than the 3 of us probably So. Um. 12:38.60 StefanMilosavljevich It's hard man I know enough to be dangerous, but no video gets released on my channel without someone more knowledgeable than me reading it and given it the once over. So I do take that precaution all ways. Um, but yeah I know enough to be dangerous. That's for sure. 12:46.69 Cornpop Commenting. 12:53.76 Cornpop Speaking of dangerous. So this thing is saying that the wangham paper that so reduced reactive aggression and I'm reading the abstract here trying to quote it. Um. Sophisticated language enabled males of low fighting prowess to cooperatively plan the execution of physically aggressive and domineering alpha males. This system is known today as a leveling mechanism in small scale societies group structured culture selection possibly accelerated the process. So. That probably doesn't make a lot of people happy, but it is interesting. 13:30.50 archpodnet I I immediately think of the capital 2021 riots like a bunch of low status males banded together to try to use violence to overcome. Ah yeah, yeah, that's true. Yeah. 13:30.21 StefanMilosavljevich While this is one of the ah sorry get on it. 13:36.16 Cornpop And. 13:38.64 StefanMilosavljevich They would definitely consider themselves Alpha Males I'm sure if you asked the average attend they're they're not betas. They're alphas we're the sheep. Um, yeah, but that's ah so that's basically one of the main ideas behind this brain reduction. Is that humans have somehow domesticated ourselves in the same way that we've deliberately domesticated animals like cows and sheep and goats and things we've also inadvertently um, done the same process to our. 14:10.83 Cornpop Where you got against dogs. 14:17.79 StefanMilosavljevich Bodies because when if you looked at wild animals compared to their domestic counterparts. There are these certain physical features that seem to pretty consistently manifest. They get smaller smaller teeth Um, reduced. Sexual dimorphism so males and females are more similar in size and it seems that their brains are smaller and if you looked at our anatomy compared to the anatomy of some archaic Homo I Homo Erectus neanderthals people like that. You could argue that we share these same physical features as a domesticated Animal. So um, maybe we're all the sheep we've all domesticated ourselves. You know So that's the main ideas behind this this idea. 15:06.87 Cornpop Um I guess the audit that. Yeah this is on. Yeah um so I know what you're saying So it's like prognasticism I believe is like the the word for like a neanderthal's face that kind of juts out like they have a snout. 15:24.71 StefanMilosavljevich Yeah, yeah. 15:26.10 Cornpop Almost versus more than a human does and our faces are scrunched up and I'm looking here at the citations in the paper because I figured you would cite this a lot of them talk about neural crest cells and those are the cells that are either more suppressed or suppressed when you're in utero I believe. That make your cartilage. Essentially it's what makes a dog's ears flop and what's makes their face scrunch up Shorter. So I'm curious to know if that's what happens to us because that it is undeniable that our faces are a little more flat than they were. 15:51.26 StefanMilosavljevich Yeah. 16:01.27 archpodnet And a lot more flat I mean if you look at the uslopithecces you know, even homo erectus has a jutting snout. So I mean there is that trend and like the mandibles get smaller. We actually get a jaw our psychoymatic arches get smaller because they're not supporting such large. Um. Jaw muscles and sost and our saintal tip crest to disappears I mean there's that whole trend of the grasslization of our facial features. Um, but 1 of the last things that hasn't really shrunk as rapidly as some of our other facial features is our wisdom teeth and molars. Which is why people have to get wisdom teeth removed because there's still kind of this holdout ancestral feature because teeth take a little bit longer to ah I guess like basically shrink as opposed to the mandibles. So. That's why we have to get wisdom teeth taken out is just kind of this vestigial trait. Um. From when we were when we did need large teeth and large um jaw muscles to crack open much more dense eating material. 17:04.92 StefanMilosavljevich Yeah, yeah, the idea behind like you mentioned the neural crest cells I think David the idea behind that is that those cells um do affect the amount of adrenaline in. 17:13.65 Cornpop Are. 17:21.50 Cornpop Right. 17:23.50 StefanMilosavljevich Our systems and so the idea behind Maybe they're responsible for this domestication is that a wild animal maybe has more adrenaline in their system. That's why they're reacting violently. That's why they're you know it's sort of instrumental to their fight or flight ability is the adrenaline in there. 17:41.13 Cornpop What's the Fox experiment. Yeah. 17:42.58 StefanMilosavljevich Yeah, as the adrenaline in their system. So when these ah animals are being domesticated and selected for sociability. Maybe this affects the amount of adrenaline in their system. But these neural crest cells I think that's why they're Called. Don't just develop our. Ah, adrenal system. They also affect our skulls our ears all sorts of parts of our body. They just develop into various parts of our body. So Maybe when you dial down the adrenaline. You also get small teeth and floppy ears. Um, but that's one of the ideas. Behind this brain size reduction is that we have domesticated ourselves. However, spanner in the works This reduction in brain size seems to have occurred in the last say 30000 years but we have been on this. Process of domestication for presumably much longer than that. So Why did we develop all these other features but still maintain a big brain. Maybe there's some other factor that's ah, affecting our brain size. 18:50.26 Cornpop Interesting. Um, yeah. 18:51.74 Connor So yeah and I think on that note, we're we'll end the segment and we'll talk about this a little bit more ah is episode 1 Oh 5 of a life and ruins podcast. We'll be right back. 19:02.72 archpodnet I I'm going to do a quick um Chris has removed our or the ad at the beginning of our episodes telling people not to be on the all shows feed is over so I'm going to do another one here. So Chris if you could put this before the intro. 19:12.35 Cornpop Oh no. 19:18.16 archpodnet Hi everybody rather pleasure listen to our show and they all shows food. Um, but if you are listening to our show and the all shows for the big stop and subscribe to our podcast subscribe like directly to our podcast and listening to our show on our page allows us to grow. And Newsoles Don Met those metrics to get um patrons subscribers are ad advertising. So if you could just go ahead and do that that would greatly appreciated now on to the show.