Welcome to Stuff You Should Know fromhouse Stuff Works dot com. Hey, and welcome to the podcast. I'm Josh Clark, and there's Charles W. Chuck Bryant, and this is stuff you should Know. Yes, I think this might complete our brain. I don't know about that, because we've done Einstein's brain, You've done difference between men and women's brain, and now we're tackling brain size, which is sort of gets on both of us a little bit. It does, but there's always new findings. So yeah, that's what I'm saying. If there's ever an ongoing sweet, it's got to be the brain. Man. It's growing all the time. It's changing shape, changing size, changing connections. You could almost say that sweet is plastic plasticity. Baby. Yeah, that's right. Um, you sent me something that I think we should talk about first, Chuck. This is kind of like, um, this is just like a ad bag hodgepodge of loosely related studies that all find that we don't really know the answer to the question like does a big brain mean a smarter person? Yeah, because there's a lot of different conflicting findings. Well, a few million years ago, our brains started growing a lot and that kind of timed out with becoming smarter and using tools and things. So I mean there's a little bit of you call it evidence. Well, yeah, there's definitely some plenty of evidence. I think that's what the confounding part is that there's plenty of evidence that, yes, as a brain grows, it is correlated to intelligence. But then that's only holding true up to a point. I sounded like a Soviet immigrant. Just then that's only holding true up to a certain point. Right. He's in Branson, Missouri, though, did you know that. I think he's got like his own restaurant or something. Well, he's own theater, and I think all the theaters are food buttery. We should go to Branson, man that I want to see what that place is all about. Okay, you know yeah, I mean it's a parade of stars. If it's nineteen seventy three, you know. Uh, I bet your boy Ronnie mills Up is there. Yeah. If he doesn't have a place there, I'll bet he plays Branson fairly regularly. He sub lets he would play well there. Um, so Branson, how do we even get them? Yeah? So brain size does correlate to intelligence to a certain extent, But you can point out like, well, sperm whale has a seventeen pound brain. Holy cow, it must be the smartest animal on the planet. Well it's not. I'm sorry to tell you sperm whale fans that it's not the smartest animal on the planet. Humans are the smartest animal on the planet, and don't you forget it. But we don't have the largest brains, so you kind of take that idea of well, if it's not brain size, maybe it has to do with the size of your brain in relation to your body. Then we started to get a little closer to jack pot. But even still, I just want to I want to spoil it for everybody. There's no definitive answer. Yeah, but sometimes those are the best ones because we get to explore all this stuff and we can't really get anything wrong because nobody knows what's right. Oh I like this, then, yeah, I've turned you know these? Yeah, now now I feel good about this because I can't be wrong right exactly. Well, I guess we should start off with um a little bit about what determines what size brain you do have. And again they don't know everything about it, but they think that genetics plays apart. They know this in part by studying twins and identical twins um have, of course the same genes. Fraternal twins have about half the same genes, and there's a greater correlation in brain size if you're identical then fraternal. Yeah, so genetics, you know, looks like it probably plays a role. Yeah, And they've done a lot of exploration into what genes in particular have to do with brain size, and they've isolated a few. Um one is called beta catenin. There's a hyphen in there too. It's pretty flashy gene not beta carotene, no caten in. And who's who's coming up with the naming convention for genes? They are all over the place, like you can't look at the name of a gene and be like, that's obviously a gene unless there's like a couple of weird consonants and a number and then another consonant. Then you're like, well, that's a gene. But you're right, that's a gene. It is a gene, and it's a gene that they know controls brain growth because they've injected poor mice with this stuff until their heads exploded. Exactly their heads they fell short of exploding. But a lot of the mice died as a result of their heads growing too big. But they're they're they're brain means grew big, and as a result of their brains growing big, they exhibited um more intelligence, higher cognitive function. They injected these things with a gene your brain. That yeah, that made them smarter. But that, like Molly points out in this article, you can't. That doesn't mean we should start doing that because these mines are dying, so you can't. Just you can't play god, as they say, no, But it does make you wonder, like, Okay, you don't want to shoot up beta caton in like before the s A T S or anything like that, but like, is there a way to kind of tamper a little less but still tamper with that gene something put under your tongue and let it dissolve. Maybe sure, like you know, just epigenetically, just a tad bit. Yeah not maybe you know, amplify it just a tad and see what happens. But it would cause your brain to grow because that gene is partially responsible for the size that your brain gets to. That's right, as far as large your brains go. Yes, like it makes it larger. Yes, if you want to talk smaller brains, there's another gene. And boy, you're right. The names are all over the place, just convention wise. It's not like they have different names that some are numbers and dashes. And to get it together, people AESPM. It's an abbreviation for abnormal spindle like, uh, micro cephalely associated, that's the name of the gene. Yeah, that's it's just shameful. And they say microcephalely associated because that is a condition that you've probably seen before when you're born with a small head and small brain, which probably means you're going to have some cognitive impairment. So so right there, smaller brain is is correlated to lesser or lower faculty your cognitive function. Yeah, we should look into that more for another podcast. So I think it's uh from the images I saw, it looks like you remember like the movie Freaks. Yes, that that guy. I think that's so cute the deal. I think you have like normal sized nose and ears and eyes, but your actual head and skull and brain or smaller. You don't look like the the um the African Safari guy from Beetle Chuice not proportionately shrunk, right, it's yeah, how you get him down so small? Right? Favorite? What was that guy's name from Freaks? I've read about him before. No, he had his stage name. It was like Topsy or Flopsy or something like that, and he apparently like the greatest personality of all time, just so lovable and was just exploited basically his whole life until that movie like kind of got vengeance for him because he was a real life side show performer. Well that's good. Yeah, Topsy. It wasn't Topsy that was the elephant that Edison electrocuted, but it was something along those lines. Just a fun, fun name. Yeah, so check. There's another gene. This is a little more genetically sounding e m x two. Yeah that sel sounds like a dirt bike or a gene. Yeah, it's um Again, we're not We're not saying like, well, these are the genes that provide you with your intellect. These are just genes that they are saying these things have to do with the size of your brain, and they we also have figured out that if you mess with these genes, you may also be messing with cognitive function. So we're laying the groundwork here, everybody to bear with us. The e m x two gene UM apparently has to do with the growth of your UM, the functional subdivisions of the cortex. You have different cortices, they're responsible for different things. So like if in that New York Times article you seth me, the guy uses the visual cortex as an example, UM, where like you get all your visual sensory input and your brain puts it all together. That cortex, that region of your brain is responsible for a fairly specific but also very um complicated task. Now, this one functional cortex that the e m x two gene is responsible for UM has to do with basically input, sensory input and motor output. So your behavior, Like, um, if I came across this desk at you and like pinched your cheeks, you'd like jump back, I'd say, what is it Wednesday? Right? Yeah, you would make the connection that's Wednesday. Your behavior would occur. So, UM, this e m x two gene has to do with that cortex and its size. What they found is that bigger is not necessarily better. If you have a lower expression of it and you have a smaller subdivision of that cortex, you're not to do very well behaviorally functionally, like you won't be able to hit a baseball very well, all right, but if it's too big, if that gene over expresses, you don't get better at hitting a baseball. With this in particular, it seems to be fine tuned. So if you're not hitting that sweet spot, you're never going to hit a baseball. And there may be myriad other problems, but you're definitely not gonna hit that baseball. So that means you're born with baseball talent pretty much. Yeah, because it's genetic, and there's like there's some people who are so close to perfect that like baseball just comes naturally to right, right, like Robert Redford exactly. Yeah, he really gave those lights a wall. Yeah, he's the natural. So that's the genetic basis of it. Chuck. Yeah, and uh, I guess we should talk some about size if it's important, because this is sort of the debate that keeps going on and on. Is brain size corollary to intelligence levels? Uh? They did find or they have found links between if you have a lot of brain growth, um, if it's disproportionate early on, Um, they've linked that then early I mean the first twelve months too. They've linked that to autism. So super rapid growth may what it may do is just prevent those neural connections from happening like they should, right. Um And actually, well that's kind of links into that tethering thing I sent you too, it does, which we will talk about later. Um. In biology, though, is there's kind of this consensus that it's it's not the only determinant, that it has a lot to do with um environment as well, I think kind of as a whole. People who investigate correlations between brain size and intelligence have totally abandoned the idea that, um, like, your brain is predetermined to grow a certain way and then that's the Yeah. Well, size wise, they've also found that if you have a d h D, if you're an adolescent, your brain might be three to four percent smaller than your classmate who does not have a d h D. UM, and your brain shrinks as you get older, but doesn't necessarily lose functionality because of the shrinkage. It's not to say when you get older, you don't, you know, loose functionality, but it's not due to the size. No. They think that, um, it's probably mostly due to really Okay, that you're you're synapsies are just kind of built up with gunk remnant proteins from years and decades of firings. Then you shake that off by continuing to use it. Yes, that's one thing. But also they've recently found that, um, while you sleep, they think now the function of sleep. They didn't notice it before until I don't know what kind of new imaging technology they used, but they found out that there's this whole channel of like basically a sewage system that just clears out all the gunk from your brain while you're sleeping at night. And it's just that's why you are cognitively refreshed. That makes sense from sleep. And we've done we did one on why sleep is important, right, Yes, I think that was in there. We've done a bunch. There's a whole sleep suite too, alright. So one of the reasons why uh people are still debating whether or not brain size equals more intelligence or less intelligence is because when there are a lot of different ways to measure the brain, um, you know, like do you take a tape measure and go around it or do you go from the middle out or do you do it proportioned to your body size, which is a real measurement called insephalation quotient. And if they're talking about your body size, what if you're super fat? Like, there are all these different ways and no one I don't think has ever come to a consensus on the best way to actually do the measurement in the first place. No. And there's another a really big outstanding question is how do you measure intelligence? Like our i Q tests actually legitimate. Yeah, So when you have two parts of your equation that are both hinky, how can you come up with an answer? Well, it depends, like if you're comparing species to species, that in cephilization quotiation actually has been proven to be pretty effective. So like the proportion of your brain to your body size is a pretty decent predictor of your e Q is what it's called as a mammal. Yes, as as a mammal. When you go outside of mammals, it gets less and less effective. Um. But with humans, for example, we our our brain is like two point seven pounds on average, it's something like around two to three. I've seen as much as five, but I think it's about three percent of our body weight. Um. But it uses up a about of the energy, which is another measure like how much energy is your brain require? The more energy your brain requires. In addition to things like eq, you can get a pretty good idea of like how intelligent that being is. Well, Einstein's brain remembers this was the same size, but different parts were bigger than others. Right, so supposedly let's come under fire lately. Yeah, somebody was like, these studies are terrible, Like, you can't make these huge leaps and bounds and um in conclusions just from a couple of strips of brain tissue. But apparently most studies have. Well I think that's sort of like a juicy thing that people like to talk about Einstein's brain. Yeah, you know, I could see people making that leap, right, and the idea that like, oh, well, Einstein's brain is just like anybody else's, Well, that means that anybody could be a genius. You know. It really argues in favor of the nurture side of things. But if his brain is structurally different, well, the genius is an inborn natural thing. It's just nature versus nurture played out on pout. Einstein sliced up brain. Yeah, that lived in a garage for many years, like everyone's brain. So here's the most controversial thing, Like when you're comparing species to species, like you said, especially among mammals, chuck. Um, it's easier to say like, yes, this EQ thing works, but within a single species that when things starting to fall apart, for instance, specifically among humans. Um, men tend to have about a hundred grahams more mass to their brain than women. But if a bigger brain means that you are more intelligent, then does that mean that men are more intelligent than women? I think we all know that women are more intelligent than men. Okay, so then brain size really has nothing to do with it, at least intra species, That's what I'm saying. But um, there have been plenty of studies that I'm sure got a lot of people's hackles up. Um. One guy named Michael McDaniel, who's a psychologist, basically entered the news cycle bursting onto the scene in two thousand five, which is always a little bit like yeah's this guy right, Yeah, But he came up with a study that was ready made for CNN. Yeah. I mean he said flat out that bigger brains means you're smarter and that I E or e G. Which one is it? Uh? I EVE in this case, men are smarter than women. Yeah, yeah, that's what he was saying. Yeah, because he basically put brain imaging tests and i Q tests together and said, well, there's a direct correlation between the two. And again with these tests they did, uh, they compared, Um, they converted s A T scores of a hundred thousand seventeen and eighteen year old to an ice Q score And I don't see why they and had to do that, and they found that males average three point six three IQ points higher. But um, I don't know. It just seems really hinky because first of all, they used ten thousand more females and males, so that's gonna excuw things. And then it's an s A T R. What does that even mean? Yeah, it has been proven time and time again to be biased. Yeah, and then they converted that to an i Q source with some like I guess machine, seems like some things would be lost in translation. Yeah, I think it's a bunch of bunks. So yeah, I think you're not alone in the idea that it's a bunch of bunks. So a lot of um scientists have said, Okay, all right, this whole brain size correlating to intelligence stinks of phrenology when you're talking about looking at it just in the human species, right, So what is it though? I mean, surely there's got to be some biological part or aspect of the brain that correlates to intelligence. If it's not size in maybe it's the number of neurons that you have, Yeah, neural connections. A lot of people have thought that that was kind of the second to most recent wave in thinking about what brain structure correlates to intelligence. Yeah, this um was this the New York Times one about the tether hypothesis. This is just December of last year, so it's pretty recent. And a couple of neuroscientists from HAVID so you know they're right. Um, they had a pretty simple explanation. Um, when back in the day when tooktok had a little bitty tiny brain. Uh. Their argument is that the neurons were tightly tethered in a pretty simple connection pattern, and that when our brains started getting bigger, those tethers were torn apart and it formed h It enabled us, We formed new neurons and new neural pathways and new circuits. That that makes a lot of sense to me. Yeah, it's like the brain size might have been about the same, and it was, but the neuro connections were still following the primal animal connectivity, where it's like they they connect in a predictable way, whereas with this untethered idea, they just blossomed out. And do you know the idea of um, like like what neuro connections look like today, rather than following like straight predictable lines, they were all over the place. And from these new connections, new associations arose, and that gave rise to intellect. According to this, it's pretty simple smart. Yeah, I like, I think sometimes the simplest hypotheses might be on target with acam's razor my friend, or maybe they just speak to me because I'm a dummy other ball um. So that's that is a competing explanation. Another one that I've seen, uh says that it's not not the neurons, not the number of neurons, not even the number of neural connections. It's the chemistry and the complexity of the neuro train sbmitters that are being conducted between these neurons, and from this has kind of come this new idea that it's folly to even say, well, humans are obviously smarter than a bottle knows dolphins, even though they're smart, because the bottle knows dolphins. Um experience understanding of life is so radically different from humans. Yeah, you can't. You can't compare intellect to intellect. Yeah you can't say, well, a dolphin can't, you know, talk and speak, but I can't do things a dolphin can do. Or maybe dolphins are speaking, I mean, to one another, just not to us. That doesn't make them less intelligent. So long, and thanks for all the fish and we're not Yeah, that's a good one, and we're not like anthropomorphizing here. Basically, there's there is very little um point I guess. Yeah, I don't get it to comparing the two. There's tremendous point to getting to cracking this code and understanding dolphin intellect or bird intellect, degreed octopus intellect and human intellect. But to compare them is it's an exercise and futility. There's no point to it. I don't get it. Yeah, I mean, compared dolphin A to dolphin B one, maybe smarter one might have a little patchy mustache and hang out at the gas station a lot. And that's not the smart one. Yeah. I think people do this to either. I think they're trying to claim some either superiority of animals over humans or humans over animals, right, And that's kind of that's a big issue of these days, Like there there are groups um animal rights groups that are trying to further animal rights by getting them inalienable rights like humans have right, which would really screw up the zoos system. Yeah, you can look for a podcast on that too. We did. Yeah, that was a good one. I think we landed pretty heavily against zoos. Yeah, we did. But to each their own. But I haven't been to a zoo since then. What is this Project Enigma? I thought that was pretty interesting. It was another genetic thing, this um it was. It was neat though in that like this Australian researchers said, Hey, we have something called internet and m r I S and willing participants, so everybody starts sending in your brain scans. Is that who proved that the complexity of the neural activity was the most important thing? Was that project? No, that was a different one. That was there was a New Scientist or no Scientific American article that um that explored that idea as the the synaptic proteins that create intellect or intelligence. But the Project Enigma basically found that there is a single mutation on a specific gene where if you have a C instead of T, I think you um have a bigger brain. And they correlated that to more intelligence. Yeah, but again using the i Q test. Well, what I'm tired of are the studies that throw out the results that don't make a fun headline, you know. Right, There was this one um from Smithsonian magazine from December of last year that uh, well they it wasn't from them, was from the Proceedings of the Royal Society b and Smithsonian reported on it. But it was a study of country mice and city mice. Well a bunch of animals. But they found that city mice and vol I don't even know what that is, v l E. Prairie vols? What is that? Like? They're very sweet. They they are monogamous like a bowl eevil, No, that's a bug. A bowl is like a like a prairie dog. You should look up prairie balls. Very cute and the idea that they're very sweetest, even better. You wouldn't like shoot one for being on your property. No, I mean some people would, but not good people. I know someone who does that kind of thing, shoots at voles, not bowls, but woodchucks with with the air rifles. That's not nice. He knows who he is. Boom. But this study basically said that city mice and city bowls had larger brains than country mice. And of course that makes a big headline because people are going to try and make the point that, you know, people that live in urban environments are smarter and the hillbillies out in the country are dumber. They study ten animals, only two of them showed that, and some of them showed the opposite that the I think bats and shrew's actually the country versions had larger brains. So they don't say any of that in the study because they just want a headline that says, you know, if you live in a city, you're smarter. Yeah, and we I mean we've been addressing this lately, like there is like a symbiotic collusion between bad science and bad science reporting, you know, yeah that results and stuff like that, where it's just like, you know, city city people are smarter than country people. Says this one study that where the data was massaged. Well, can you city person, can you go make butter with your hands? I have to say, can you farm land? No? Of course not um, but there it is possible that there's a basis to this. Whereas city people are, their brains are more stimulated than country folk perhaps, and so more neural connections, more plasticity takes place. I don't I don't think that's true. I think there's just as much stimulation in nature as there is in a city full of people. Spends once you're stimulated by I look at Dar when he spent his entire life living in the country. Yeah, for sure, But I mean like we're also we also have hundreds of thousands of years of latent inhibition built up against a lot of the stuff in nature, whereas the stuff in Times Square is relatively new, so our brain isn't doesn't defend against it quite as easily. So hence we're possibly more stimulated. I think it depends on what you're doing with your time. Sure, if you're out the country sitting around watching reality TV. If you're in your apartment watching reality TV. I found this other study today to um from Germany about pornography may reduce your brain size. Another kind of sexy headline, right and um sample size at three And it's always self reported to and when you're dealing with porn and self reporting, do you look at check the box? Do you think your brain is small? Check the boom? Yeah? How smart are you? Somebody called the Uh they cannot say that watching porn caused a decrease in brain matter, but they did say they found that the volume of striatom, a brain region that's been associated with reward processing and motivated behavior, was smaller the more pornography you consumed. And basically where they're at is we don't know whether it's causing this or if people did. Oh yeah, they gets struck dumb and they're like, yeah, they're just end up watching porn more like in Idiocracy again that movie. There's probably been no other movie that's made more of a legitimate appearance in our episodes than that MOVIECCY, Yeah, yeah, I think you're right. Yeah, my judge, he's onto something. Do you watch Silicon Valley? I haven't I know. Uh, Kamal nan Giani's in it. Yeah, he's funny. Does he do well? Yeah, Martin Starr, it's uh yeah, it's a good show. Nice, it's I think it was high time that someone took on the tech industry and like a comedy like that. Yeah, leave it to Mike Judge. I know if there's any crusader crusader people feeling good about, right, Yeah, it's Judge. Uh. If you want to know more about brain size in relation to whatever, just type in brain in the search part house. So first dot com and it's get lost. That's what I say. Type in brain and just go on a trip. Man. All right, that's right. Journey. I think that's the slogan for how stuff works. That's right, um answers, I said, search far as the time for what? Listener mail? Yes, okay, I'm gonna call this help for a fan in need. It's hey, guys, I want some help please. My wife and I are expecting our first kid this summer, and thirteen days ago we also found out that my wife has staged four breast cancer. So we are spending our third trimester getting chemo. My goodness, I know, Uh, We're gonna kick cancer in the butt, we have no doubt, but we're scared and overwhelmed. Obviously, we're doing chemo now. Then we'll have the baby get more chemo than bilateral mastectomy than radiation. We have great doctors and great fins and families. So even in the face of this, we feel very lucky. Uh. And by the way, I gotta follow up more recently. That says, uh, there is no gestational ibtes and the cancer is already shrinking. Oh, it's great. So thanks are going great so far. Thanks for keeping us in suspense. I know I was gonna wait till the end. Uh. And he asked for a couple of favors. He said, First of all, if you want to follow and promote my tumbler, uh to keep people updated, it is um h T t P colon slash slash gala freaki diky g A l l i U f r e k y d e e k y dot tumbler dot com. He says, we're huge nerds and doctor who fans. So that was lost on me some doctor who reference, I guess apparently, so does that have to do with the phone booth. Maybe that's the only thing you know about same here. Um. Secondly, I'm biking a hundred and fifty miles to raise money, and could you plug that? And you can go to g O O dot g L slash two w j z x Q. People don't like normal words, well that's one of those shortened U R l oh. I see it's a google. Uh. And then third, how about a shout out. I think that's what we're doing here. My wife is a little shy, so just use her nickname the mayor. That's hilarious. Whereas a sash during chemo and childbirth. I guess, so, I mean, I call Emily the boss, so I guess it's the mayor. But the mayor is like the boss of several bosses, I would guess. Yeah. We used to call my friend Justin who you know, the mayor of Atlanta, because everywhere he went nobody knew him. He's a fellow. But now we just call him the manager of Atlanta because everywhere you go he has some improvement to that place, like the lighting is not quite right, or the door should be over there, the kitchen is not located properly Brits Yeah. Uh. And then forth, my wife works in public policy, specifically helping women and families get themselves out of poverty and advocating for low income workers. So there you have it. An awesome an incredible woman who dedicates her considerable talents helping others. He's pregnant and his breast cancer. Kind of hard to say no, right, I'm not above guilt tripping. So Bob from Swithmore, Pennsylvania. UM, there you go. People should go and check out that stuff and support your bike ride. And I hope things have continued to progress well for your wife and child and keep us updated. Yeah, and you keep me updated at the very least. If not everybody listening, I will. Okay, thanks a lot, Bob and the mayor, good luck to you both. And um, let's see if you want to get in touch with us, whether you're a mayor a provincial governor who knows, you can get in touch with us on Twitter at s Y s K podcast. You can join us on Facebook dot com slash stuff you Should Know. You can send us an email to Stuff Podcast at how stuff Works dot com and join us at our home on the web, Stuff you Should Know dot com. For more on this and thousands of other topics. 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Welcome to Stuff You Should Know fromhouse Stuff Works dot com. Hey, and welcome to the podcast. I'm Josh Clark, and there's Charles W. Chuck Bryant, and this is stuff you should Know. Yes, I think this might complete our brain. I don't know about that, because we've done Einstein's brain, You've done difference between men and women's brain, and now we're tackling brain size, which is sort of gets on both of us a little bit. It does, but there's always new findings. So yeah, that's what I'm saying. If there's ever an ongoing sweet, it's got to be the brain. Man. It's growing all the time. It's changing shape, changing size, changing connections. You could almost say that sweet is plastic plasticity. Baby. Yeah, that's right. Um, you sent me something that I think we should talk about first, Chuck. This is kind of like, um, this is just like a ad bag hodgepodge of loosely related studies that all find that we don't really know the answer to the question like does a big brain mean a smarter person? Yeah, because there's a lot of different conflicting findings. Well, a few million years ago, our brains started growing a lot and that kind of timed out with becoming smarter and using tools and things. So I mean there's a little bit of you call it evidence. Well, yeah, there's definitely some plenty of evidence. I think that's what the confounding part is that there's plenty of evidence that, yes, as a brain grows, it is correlated to intelligence. But then that's only holding true up to a point. I sounded like a Soviet immigrant. Just then that's only holding true up to a certain point. Right. He's in Branson, Missouri, though, did you know that. I think he's got like his own restaurant or something. Well, he's own theater, and I think all the theaters are food buttery. We should go to Branson, man that I want to see what that place is all about. Okay, you know yeah, I mean it's a parade of stars. If it's nineteen seventy three, you know. Uh, I bet your boy Ronnie mills Up is there. Yeah. If he doesn't have a place there, I'll bet he plays Branson fairly regularly. He sub lets he would play well there. Um, so Branson, how do we even get them? Yeah? So brain size does correlate to intelligence to a certain extent, But you can point out like, well, sperm whale has a seventeen pound brain. Holy cow, it must be the smartest animal on the planet. Well it's not. I'm sorry to tell you sperm whale fans that it's not the smartest animal on the planet. Humans are the smartest animal on the planet, and don't you forget it. But we don't have the largest brains, so you kind of take that idea of well, if it's not brain size, maybe it has to do with the size of your brain in relation to your body. Then we started to get a little closer to jack pot. But even still, I just want to I want to spoil it for everybody. There's no definitive answer. Yeah, but sometimes those are the best ones because we get to explore all this stuff and we can't really get anything wrong because nobody knows what's right. Oh I like this, then, yeah, I've turned you know these? Yeah, now now I feel good about this because I can't be wrong right exactly. Well, I guess we should start off with um a little bit about what determines what size brain you do have. And again they don't know everything about it, but they think that genetics plays apart. They know this in part by studying twins and identical twins um have, of course the same genes. Fraternal twins have about half the same genes, and there's a greater correlation in brain size if you're identical then fraternal. Yeah, so genetics, you know, looks like it probably plays a role. Yeah, And they've done a lot of exploration into what genes in particular have to do with brain size, and they've isolated a few. Um one is called beta catenin. There's a hyphen in there too. It's pretty flashy gene not beta carotene, no caten in. And who's who's coming up with the naming convention for genes? They are all over the place, like you can't look at the name of a gene and be like, that's obviously a gene unless there's like a couple of weird consonants and a number and then another consonant. Then you're like, well, that's a gene. But you're right, that's a gene. It is a gene, and it's a gene that they know controls brain growth because they've injected poor mice with this stuff until their heads exploded. Exactly their heads they fell short of exploding. But a lot of the mice died as a result of their heads growing too big. But they're they're they're brain means grew big, and as a result of their brains growing big, they exhibited um more intelligence, higher cognitive function. They injected these things with a gene your brain. That yeah, that made them smarter. But that, like Molly points out in this article, you can't. That doesn't mean we should start doing that because these mines are dying, so you can't. Just you can't play god, as they say, no, But it does make you wonder, like, Okay, you don't want to shoot up beta caton in like before the s A T S or anything like that, but like, is there a way to kind of tamper a little less but still tamper with that gene something put under your tongue and let it dissolve. Maybe sure, like you know, just epigenetically, just a tad bit. Yeah not maybe you know, amplify it just a tad and see what happens. But it would cause your brain to grow because that gene is partially responsible for the size that your brain gets to. That's right, as far as large your brains go. Yes, like it makes it larger. Yes, if you want to talk smaller brains, there's another gene. And boy, you're right. The names are all over the place, just convention wise. It's not like they have different names that some are numbers and dashes. And to get it together, people AESPM. It's an abbreviation for abnormal spindle like, uh, micro cephalely associated, that's the name of the gene. Yeah, that's it's just shameful. And they say microcephalely associated because that is a condition that you've probably seen before when you're born with a small head and small brain, which probably means you're going to have some cognitive impairment. So so right there, smaller brain is is correlated to lesser or lower faculty your cognitive function. Yeah, we should look into that more for another podcast. So I think it's uh from the images I saw, it looks like you remember like the movie Freaks. Yes, that that guy. I think that's so cute the deal. I think you have like normal sized nose and ears and eyes, but your actual head and skull and brain or smaller. You don't look like the the um the African Safari guy from Beetle Chuice not proportionately shrunk, right, it's yeah, how you get him down so small? Right? Favorite? What was that guy's name from Freaks? I've read about him before. No, he had his stage name. It was like Topsy or Flopsy or something like that, and he apparently like the greatest personality of all time, just so lovable and was just exploited basically his whole life until that movie like kind of got vengeance for him because he was a real life side show performer. Well that's good. Yeah, Topsy. It wasn't Topsy that was the elephant that Edison electrocuted, but it was something along those lines. Just a fun, fun name. Yeah, so check. There's another gene. This is a little more genetically sounding e m x two. Yeah that sel sounds like a dirt bike or a gene. Yeah, it's um Again, we're not We're not saying like, well, these are the genes that provide you with your intellect. These are just genes that they are saying these things have to do with the size of your brain, and they we also have figured out that if you mess with these genes, you may also be messing with cognitive function. So we're laying the groundwork here, everybody to bear with us. The e m x two gene UM apparently has to do with the growth of your UM, the functional subdivisions of the cortex. You have different cortices, they're responsible for different things. So like if in that New York Times article you seth me, the guy uses the visual cortex as an example, UM, where like you get all your visual sensory input and your brain puts it all together. That cortex, that region of your brain is responsible for a fairly specific but also very um complicated task. Now, this one functional cortex that the e m x two gene is responsible for UM has to do with basically input, sensory input and motor output. So your behavior, Like, um, if I came across this desk at you and like pinched your cheeks, you'd like jump back, I'd say, what is it Wednesday? Right? Yeah, you would make the connection that's Wednesday. Your behavior would occur. So, UM, this e m x two gene has to do with that cortex and its size. What they found is that bigger is not necessarily better. If you have a lower expression of it and you have a smaller subdivision of that cortex, you're not to do very well behaviorally functionally, like you won't be able to hit a baseball very well, all right, but if it's too big, if that gene over expresses, you don't get better at hitting a baseball. With this in particular, it seems to be fine tuned. So if you're not hitting that sweet spot, you're never going to hit a baseball. And there may be myriad other problems, but you're definitely not gonna hit that baseball. So that means you're born with baseball talent pretty much. Yeah, because it's genetic, and there's like there's some people who are so close to perfect that like baseball just comes naturally to right, right, like Robert Redford exactly. Yeah, he really gave those lights a wall. Yeah, he's the natural. So that's the genetic basis of it. Chuck. Yeah, and uh, I guess we should talk some about size if it's important, because this is sort of the debate that keeps going on and on. Is brain size corollary to intelligence levels? Uh? They did find or they have found links between if you have a lot of brain growth, um, if it's disproportionate early on, Um, they've linked that then early I mean the first twelve months too. They've linked that to autism. So super rapid growth may what it may do is just prevent those neural connections from happening like they should, right. Um And actually, well that's kind of links into that tethering thing I sent you too, it does, which we will talk about later. Um. In biology, though, is there's kind of this consensus that it's it's not the only determinant, that it has a lot to do with um environment as well, I think kind of as a whole. People who investigate correlations between brain size and intelligence have totally abandoned the idea that, um, like, your brain is predetermined to grow a certain way and then that's the Yeah. Well, size wise, they've also found that if you have a d h D, if you're an adolescent, your brain might be three to four percent smaller than your classmate who does not have a d h D. UM, and your brain shrinks as you get older, but doesn't necessarily lose functionality because of the shrinkage. It's not to say when you get older, you don't, you know, loose functionality, but it's not due to the size. No. They think that, um, it's probably mostly due to really Okay, that you're you're synapsies are just kind of built up with gunk remnant proteins from years and decades of firings. Then you shake that off by continuing to use it. Yes, that's one thing. But also they've recently found that, um, while you sleep, they think now the function of sleep. They didn't notice it before until I don't know what kind of new imaging technology they used, but they found out that there's this whole channel of like basically a sewage system that just clears out all the gunk from your brain while you're sleeping at night. And it's just that's why you are cognitively refreshed. That makes sense from sleep. And we've done we did one on why sleep is important, right, Yes, I think that was in there. We've done a bunch. There's a whole sleep suite too, alright. So one of the reasons why uh people are still debating whether or not brain size equals more intelligence or less intelligence is because when there are a lot of different ways to measure the brain, um, you know, like do you take a tape measure and go around it or do you go from the middle out or do you do it proportioned to your body size, which is a real measurement called insephalation quotient. And if they're talking about your body size, what if you're super fat? Like, there are all these different ways and no one I don't think has ever come to a consensus on the best way to actually do the measurement in the first place. No. And there's another a really big outstanding question is how do you measure intelligence? Like our i Q tests actually legitimate. Yeah, So when you have two parts of your equation that are both hinky, how can you come up with an answer? Well, it depends, like if you're comparing species to species, that in cephilization quotiation actually has been proven to be pretty effective. So like the proportion of your brain to your body size is a pretty decent predictor of your e Q is what it's called as a mammal. Yes, as as a mammal. When you go outside of mammals, it gets less and less effective. Um. But with humans, for example, we our our brain is like two point seven pounds on average, it's something like around two to three. I've seen as much as five, but I think it's about three percent of our body weight. Um. But it uses up a about of the energy, which is another measure like how much energy is your brain require? The more energy your brain requires. In addition to things like eq, you can get a pretty good idea of like how intelligent that being is. Well, Einstein's brain remembers this was the same size, but different parts were bigger than others. Right, so supposedly let's come under fire lately. Yeah, somebody was like, these studies are terrible, Like, you can't make these huge leaps and bounds and um in conclusions just from a couple of strips of brain tissue. But apparently most studies have. Well I think that's sort of like a juicy thing that people like to talk about Einstein's brain. Yeah, you know, I could see people making that leap, right, and the idea that like, oh, well, Einstein's brain is just like anybody else's, Well, that means that anybody could be a genius. You know. It really argues in favor of the nurture side of things. But if his brain is structurally different, well, the genius is an inborn natural thing. It's just nature versus nurture played out on pout. Einstein sliced up brain. Yeah, that lived in a garage for many years, like everyone's brain. So here's the most controversial thing, Like when you're comparing species to species, like you said, especially among mammals, chuck. Um, it's easier to say like, yes, this EQ thing works, but within a single species that when things starting to fall apart, for instance, specifically among humans. Um, men tend to have about a hundred grahams more mass to their brain than women. But if a bigger brain means that you are more intelligent, then does that mean that men are more intelligent than women? I think we all know that women are more intelligent than men. Okay, so then brain size really has nothing to do with it, at least intra species, That's what I'm saying. But um, there have been plenty of studies that I'm sure got a lot of people's hackles up. Um. One guy named Michael McDaniel, who's a psychologist, basically entered the news cycle bursting onto the scene in two thousand five, which is always a little bit like yeah's this guy right, Yeah, But he came up with a study that was ready made for CNN. Yeah. I mean he said flat out that bigger brains means you're smarter and that I E or e G. Which one is it? Uh? I EVE in this case, men are smarter than women. Yeah, yeah, that's what he was saying. Yeah, because he basically put brain imaging tests and i Q tests together and said, well, there's a direct correlation between the two. And again with these tests they did, uh, they compared, Um, they converted s A T scores of a hundred thousand seventeen and eighteen year old to an ice Q score And I don't see why they and had to do that, and they found that males average three point six three IQ points higher. But um, I don't know. It just seems really hinky because first of all, they used ten thousand more females and males, so that's gonna excuw things. And then it's an s A T R. What does that even mean? Yeah, it has been proven time and time again to be biased. Yeah, and then they converted that to an i Q source with some like I guess machine, seems like some things would be lost in translation. Yeah, I think it's a bunch of bunks. So yeah, I think you're not alone in the idea that it's a bunch of bunks. So a lot of um scientists have said, Okay, all right, this whole brain size correlating to intelligence stinks of phrenology when you're talking about looking at it just in the human species, right, So what is it though? I mean, surely there's got to be some biological part or aspect of the brain that correlates to intelligence. If it's not size in maybe it's the number of neurons that you have, Yeah, neural connections. A lot of people have thought that that was kind of the second to most recent wave in thinking about what brain structure correlates to intelligence. Yeah, this um was this the New York Times one about the tether hypothesis. This is just December of last year, so it's pretty recent. And a couple of neuroscientists from HAVID so you know they're right. Um, they had a pretty simple explanation. Um, when back in the day when tooktok had a little bitty tiny brain. Uh. Their argument is that the neurons were tightly tethered in a pretty simple connection pattern, and that when our brains started getting bigger, those tethers were torn apart and it formed h It enabled us, We formed new neurons and new neural pathways and new circuits. That that makes a lot of sense to me. Yeah, it's like the brain size might have been about the same, and it was, but the neuro connections were still following the primal animal connectivity, where it's like they they connect in a predictable way, whereas with this untethered idea, they just blossomed out. And do you know the idea of um, like like what neuro connections look like today, rather than following like straight predictable lines, they were all over the place. And from these new connections, new associations arose, and that gave rise to intellect. According to this, it's pretty simple smart. Yeah, I like, I think sometimes the simplest hypotheses might be on target with acam's razor my friend, or maybe they just speak to me because I'm a dummy other ball um. So that's that is a competing explanation. Another one that I've seen, uh says that it's not not the neurons, not the number of neurons, not even the number of neural connections. It's the chemistry and the complexity of the neuro train sbmitters that are being conducted between these neurons, and from this has kind of come this new idea that it's folly to even say, well, humans are obviously smarter than a bottle knows dolphins, even though they're smart, because the bottle knows dolphins. Um experience understanding of life is so radically different from humans. Yeah, you can't. You can't compare intellect to intellect. Yeah you can't say, well, a dolphin can't, you know, talk and speak, but I can't do things a dolphin can do. Or maybe dolphins are speaking, I mean, to one another, just not to us. That doesn't make them less intelligent. So long, and thanks for all the fish and we're not Yeah, that's a good one, and we're not like anthropomorphizing here. Basically, there's there is very little um point I guess. Yeah, I don't get it to comparing the two. There's tremendous point to getting to cracking this code and understanding dolphin intellect or bird intellect, degreed octopus intellect and human intellect. But to compare them is it's an exercise and futility. There's no point to it. I don't get it. Yeah, I mean, compared dolphin A to dolphin B one, maybe smarter one might have a little patchy mustache and hang out at the gas station a lot. And that's not the smart one. Yeah. I think people do this to either. I think they're trying to claim some either superiority of animals over humans or humans over animals, right, And that's kind of that's a big issue of these days, Like there there are groups um animal rights groups that are trying to further animal rights by getting them inalienable rights like humans have right, which would really screw up the zoos system. Yeah, you can look for a podcast on that too. We did. Yeah, that was a good one. I think we landed pretty heavily against zoos. Yeah, we did. But to each their own. But I haven't been to a zoo since then. What is this Project Enigma? I thought that was pretty interesting. It was another genetic thing, this um it was. It was neat though in that like this Australian researchers said, Hey, we have something called internet and m r I S and willing participants, so everybody starts sending in your brain scans. Is that who proved that the complexity of the neural activity was the most important thing? Was that project? No, that was a different one. That was there was a New Scientist or no Scientific American article that um that explored that idea as the the synaptic proteins that create intellect or intelligence. But the Project Enigma basically found that there is a single mutation on a specific gene where if you have a C instead of T, I think you um have a bigger brain. And they correlated that to more intelligence. Yeah, but again using the i Q test. Well, what I'm tired of are the studies that throw out the results that don't make a fun headline, you know. Right, There was this one um from Smithsonian magazine from December of last year that uh, well they it wasn't from them, was from the Proceedings of the Royal Society b and Smithsonian reported on it. But it was a study of country mice and city mice. Well a bunch of animals. But they found that city mice and vol I don't even know what that is, v l E. Prairie vols? What is that? Like? They're very sweet. They they are monogamous like a bowl eevil, No, that's a bug. A bowl is like a like a prairie dog. You should look up prairie balls. Very cute and the idea that they're very sweetest, even better. You wouldn't like shoot one for being on your property. No, I mean some people would, but not good people. I know someone who does that kind of thing, shoots at voles, not bowls, but woodchucks with with the air rifles. That's not nice. He knows who he is. Boom. But this study basically said that city mice and city bowls had larger brains than country mice. And of course that makes a big headline because people are going to try and make the point that, you know, people that live in urban environments are smarter and the hillbillies out in the country are dumber. They study ten animals, only two of them showed that, and some of them showed the opposite that the I think bats and shrew's actually the country versions had larger brains. So they don't say any of that in the study because they just want a headline that says, you know, if you live in a city, you're smarter. Yeah, and we I mean we've been addressing this lately, like there is like a symbiotic collusion between bad science and bad science reporting, you know, yeah that results and stuff like that, where it's just like, you know, city city people are smarter than country people. Says this one study that where the data was massaged. Well, can you city person, can you go make butter with your hands? I have to say, can you farm land? No? Of course not um, but there it is possible that there's a basis to this. Whereas city people are, their brains are more stimulated than country folk perhaps, and so more neural connections, more plasticity takes place. I don't I don't think that's true. I think there's just as much stimulation in nature as there is in a city full of people. Spends once you're stimulated by I look at Dar when he spent his entire life living in the country. Yeah, for sure, But I mean like we're also we also have hundreds of thousands of years of latent inhibition built up against a lot of the stuff in nature, whereas the stuff in Times Square is relatively new, so our brain isn't doesn't defend against it quite as easily. So hence we're possibly more stimulated. I think it depends on what you're doing with your time. Sure, if you're out the country sitting around watching reality TV. If you're in your apartment watching reality TV. I found this other study today to um from Germany about pornography may reduce your brain size. Another kind of sexy headline, right and um sample size at three And it's always self reported to and when you're dealing with porn and self reporting, do you look at check the box? Do you think your brain is small? Check the boom? Yeah? How smart are you? Somebody called the Uh they cannot say that watching porn caused a decrease in brain matter, but they did say they found that the volume of striatom, a brain region that's been associated with reward processing and motivated behavior, was smaller the more pornography you consumed. And basically where they're at is we don't know whether it's causing this or if people did. Oh yeah, they gets struck dumb and they're like, yeah, they're just end up watching porn more like in Idiocracy again that movie. There's probably been no other movie that's made more of a legitimate appearance in our episodes than that MOVIECCY, Yeah, yeah, I think you're right. Yeah, my judge, he's onto something. Do you watch Silicon Valley? I haven't I know. Uh, Kamal nan Giani's in it. Yeah, he's funny. Does he do well? Yeah, Martin Starr, it's uh yeah, it's a good show. Nice, it's I think it was high time that someone took on the tech industry and like a comedy like that. Yeah, leave it to Mike Judge. I know if there's any crusader crusader people feeling good about, right, Yeah, it's Judge. Uh. If you want to know more about brain size in relation to whatever, just type in brain in the search part house. So first dot com and it's get lost. That's what I say. Type in brain and just go on a trip. Man. All right, that's right. Journey. I think that's the slogan for how stuff works. That's right, um answers, I said, search far as the time for what? Listener mail? Yes, okay, I'm gonna call this help for a fan in need. It's hey, guys, I want some help please. My wife and I are expecting our first kid this summer, and thirteen days ago we also found out that my wife has staged four breast cancer. So we are spending our third trimester getting chemo. My goodness, I know, Uh, We're gonna kick cancer in the butt, we have no doubt, but we're scared and overwhelmed. Obviously, we're doing chemo now. Then we'll have the baby get more chemo than bilateral mastectomy than radiation. We have great doctors and great fins and families. So even in the face of this, we feel very lucky. Uh. And by the way, I gotta follow up more recently. That says, uh, there is no gestational ibtes and the cancer is already shrinking. Oh, it's great. So thanks are going great so far. Thanks for keeping us in suspense. I know I was gonna wait till the end. Uh. And he asked for a couple of favors. He said, First of all, if you want to follow and promote my tumbler, uh to keep people updated, it is um h T t P colon slash slash gala freaki diky g A l l i U f r e k y d e e k y dot tumbler dot com. He says, we're huge nerds and doctor who fans. So that was lost on me some doctor who reference, I guess apparently, so does that have to do with the phone booth. Maybe that's the only thing you know about same here. Um. Secondly, I'm biking a hundred and fifty miles to raise money, and could you plug that? And you can go to g O O dot g L slash two w j z x Q. People don't like normal words, well that's one of those shortened U R l oh. I see it's a google. Uh. And then third, how about a shout out. I think that's what we're doing here. My wife is a little shy, so just use her nickname the mayor. That's hilarious. Whereas a sash during chemo and childbirth. I guess, so, I mean, I call Emily the boss, so I guess it's the mayor. But the mayor is like the boss of several bosses, I would guess. Yeah. We used to call my friend Justin who you know, the mayor of Atlanta, because everywhere he went nobody knew him. He's a fellow. But now we just call him the manager of Atlanta because everywhere you go he has some improvement to that place, like the lighting is not quite right, or the door should be over there, the kitchen is not located properly Brits Yeah. Uh. And then forth, my wife works in public policy, specifically helping women and families get themselves out of poverty and advocating for low income workers. So there you have it. An awesome an incredible woman who dedicates her considerable talents helping others. He's pregnant and his breast cancer. Kind of hard to say no, right, I'm not above guilt tripping. So Bob from Swithmore, Pennsylvania. UM, there you go. People should go and check out that stuff and support your bike ride. And I hope things have continued to progress well for your wife and child and keep us updated. Yeah, and you keep me updated at the very least. If not everybody listening, I will. Okay, thanks a lot, Bob and the mayor, good luck to you both. And um, let's see if you want to get in touch with us, whether you're a mayor a provincial governor who knows, you can get in touch with us on Twitter at s Y s K podcast. You can join us on Facebook dot com slash stuff you Should Know. You can send us an email to Stuff Podcast at how stuff Works dot com and join us at our home on the web, Stuff you Should Know dot com. For more on this and thousands of other topics. Is it how stuff Works dot com