Why did our brains shrink?
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- Опубліковано 25 кві 2022
- We've lost a lemon sized piece of brain. Here's three hypotheses that try to explain what happened.
I spoke about this topic on A Life In Ruins Podcast, check it out:
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Sources:
Hawks, John. "Selection for smaller brains in Holocene human evolution." arXiv preprint arXiv:1102.5604 (2011).
HENNEBERG, MACIEJ. “Decrease of Human Skull Size in the Holocene.” Human Biology, vol. 60, no. 3, Wayne State University Press, 1988, pp. 395-405, www.jstor.org/stable/41464021.
Rougier H. & Trinkaus E., 2012. In: E. Trinkaus, S. Constantin & J. Zilhão (Eds.), Life and Death at the Peştera cu Oase: A Setting for Modern Human Emergence in Europe. New York, Oxford University Press: 257-320
DeSilva, Jeremy M., et al. “When and Why Did Human Brains Decrease in Size? A New Change-Point Analysis and Insights from Brain Evolution in Ants.” Frontiers in Ecology and Evolution, vol. 9, 2021, doi.org/10.3389/fevo.2021.742639.
Leach, Helen M. “Human Domestication Reconsidered.” Current Anthropology, vol. 44, no. 3, 2003, pp. 349-368., doi.org/10.1086/368119.
Balcarcel A. M. Veitschegger K. Clauss M. and Sánchez-Villagra M. R.2021. Intensive human contact correlates with smaller brains: differential brain size reduction in cattle types. Proc. R. Soc. B.2882021081320210813 doi.org/10.1098/rspb.2021.0813
Theofanopoulou C, Gastaldon S, O’Rourke T, Samuels BD, Martins PT,
Delogu F, et al. (2017) Self-domestication in Homo sapiens: Insights from comparative genomics. PLoS ONE 12(10): e0185306. doi.org/10.1371/journal.pone....
Ampel, Benjamin C., et al. “Mental Work Requires Physical Energy: Self-Control Is Neither Exception nor Exceptional.” Frontiers in Psychology, vol. 9, 2018, doi.org/10.3389/fpsyg.2018.01005.
Wrangham, Richard W. “Hypotheses for the Evolution of Reduced Reactive Aggression in the Context of Human Self-Domestication.” Frontiers in Psychology, vol. 10, 2019, doi.org/10.3389/fpsyg.2019.01914.
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Disclaimer: Use my videos as a rough guide to a topic. I am not an expert, I may get things wrong. This is why I always post my sources so you can critique my work and verify things for yourselves. Of course I aim to be as accurate as possible which is why you will only find reputable sources in my videos. Secondly, information is always subject to changes as new information is uncovered by archaeologists.
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Remember these are hypotheses, which means no one is saying they are 100% correct, just that these ideas answer some of the patterns we observe. We're also not sure if some areas of the our brains have shrunk or if it has declined overall with no particular emphasis on a particular region. Thanks for watching you tiny brained apes!
Hypothetically, if we cloned a bunch of homo sapiens from 100-300 thousand years ago and reintroduced them into the gene pool would our species brain size increase again and would it be possible that our intellectual and cognitive potential would increase?
Could it possibly be that our brains got more folds in them so they were able to fit in a smaller casing as opposed to the brain itself shrinking?
Here's my hypothesis: survivorship bias. With agriculture (pre industrial pre antibiotics), only 50% of humans died before the age of 5 (RAG estimate from the depths of my defective memory). Who's to say that number was 60-80% before agriculture, and what if most survivors were already biased to have bigger brains???
You seemed to ignore the genetic tendancy to neoteny which domestication is fundamentally built upon. I did a thesis on domestication and neoteny, if you want any notes or citations.
Thanks, Milo, for pointing out that that there is no doubt that there are "tiny-brained apes"; they are called liberal democrats!!
It seems most likely that human minds may be more efficient than they were. Since brains are a huge resource burden, if humans can remain intelligent while shrinking their brains, that's an evolutionary advantage. Our brains may simply work better, once for ounce, than they once did.
We also have to take notes that early settlers would use and learn more applied knowledge than theoretic ones, perhaps by using and developing that knowledge daily, unlike theoretic knowledge which doesn't affect us directly, it has an impact on the brain size since it's used and trained constantly everyday.
@@Purfinex Actually, that's a sort of learned stupidity, programmed into machiavellian sociopaths by academics, both wanting to use it for their own corrupt ends:
Stupidity is ignorance sent to college.
But that doesn't reflect innate intelligence.
@@BaddeJimme i can, were you born with balls or not, case closed.(hermaphrodites are to be refereed to as the dominant genes gender, doctors assign this)
mental illness doesnt effect reality.
@@BaddeJimme uh oh, the thought police erased my comment. Must not want you to hear the truth, great age we live in.
I thought so too, I imagine it’s the same as computer chips we have grown more efficient and outsourced the less important stuff to other things. Thus getting smaller
Crows have a higher neurodensity than many other birds, that has enabled them to make simple tools, recognize people, and inform other crows of people who were good or bad to them. Perhaps humans have increased their neurodensity over time. It is difficult to know as we have no ancient samples of brain tissue to compare to that of modern humans.
Parrots, too 🥢🧃🖌️🔨🔧📎
Ackshually quite inderesting...
yeah and T rex had a freaking huge brain and it just needed it to process sensory information to hunt
Time to store some brains into jars for future scientist lmao
We could simply compare a human brain to an elephant brain. Their brain is bigger than ours, even if we aren't the same specie. But we got more neurons than they have.
Considering that humans have very complicated births due to our large heads, it could also be that mothers of babies with smaller heads were more likely to survive, and thus smaller heads meant a higher survival rate over time.
I think you're on to something. It seems to be evolutionary pressure brain size. The human brain can't just keep getting larger without a whole redesign of our bodies. It probably already reached its limit when it was a bit larger than it is today. So it seems more advantageous for the human brain to decrease in size by becoming more efficient or if our technology and collective knowledge enables it to do so.
But then, evolution would have increase human female canals ... Maybe.
@@Appytail We walk upright, which is why we have a relatively narrow pelvis.
@@maggiepie8810 I think that's because of high heels...🤔
So what you're suggesting is we lost valuable brain function in a genetic mutation so we could reproduce more... instead of a few overly intelligent peoples ruling a technologically advance global culture, we instead genetically settled for a bunch of mutant brainless bureaucratic small brained monkeys running this zoo... 😉
I think the most likely scenario is our development of written language, which freed us from having to memorize everything.
I actually propose that the creation story in Genesis isn't about the creation of the universe, but the creation of the language used to describe it.
But most people in the last 3000 years couldn’t read or write and had very little contact with the written language? Or is that incorrect? Written text were mostly used in religion and commerce, not really for wide information sharing I thought.
@@Technoticatoo as far as modern written language yes that's likely true, but it doesn't stand contrary to the original comment. 😅
But if most people did not have access to written language and couldn't read, how would that have resulted in their brains becoming smaller? And this abruptly? Wouldn't, evolutionarily, brains get smaller because more people with smaller brains successfully procreate, while bigger brained people for whatever reason did not outpace them with their progeny. I'd assume this is because brains got more efficient, not because they were used less. (Or at least certain parts dealing with memory were used less because knowledge was outsourced). And if shared external knowledge is the cause, wouldn't the trend have accelerated over time? As this has become more ubiquitous in those 3000 years? Oh and 3000 years would be an extremely short timeframe for evolutionary effects, wouldn't it? That's only around 100 generations? @@dodget3
@@dodget3…no. That certainly wasn’t how the ancient Israelites understood it and certainly not how it’s written. If you want to talk about writing about words, look at the Psalms.
I spit out my drink when you said "greatest cultural achievements" and cut to the McDonald's sign, thats hilarious
Well i mean, it tastes pretty good
A maccies coke ?
2 Q TR FOR $6 is the greatest cultural achievement
@@stargatisyuck corporate propaganda 🤮🤮🤮
Bored ape NFTs would have been funnier.
4th Theory proposed by Dr. Temple Grandin is that when humans and wolves came together both brains got smaller. For wolves, humans started doing much of the thinking work- finding the game and coordinating the hunt, deciding who breeds.... and their cerebrum got smaller; for humans the amygdala and brain regions associated with sensing the outer world got smaller as dogs were much better able to provide the vigilance needed for survival- sensing approaching threats and finding game with their superior abilities to hear and smell. Dogs provided an emotional comfort allowing our brains to relax and contemplate things not pertaining to our immediate survival and help us sleep longer and deeper without worry of attack while we're unconscious. The human and dog together become a super organism! as both the canine and primate brain is able to become more specialized at what they had a natural proclivity to. I guess this goes along with the self domestication theory, but it's also hypothesized that humans learned a lot about social cohesion from their early wolf companions who are social in ways uniquely different from primates.
Very interesting!
That is why I think dogs were around much longer than just 30,000 years ago. I feel they were possibly around 60,000 to 100,000 years ago which gave enough time for the brains to evolve at the steady pace, as well as adding features into dogs what wolves never had, i.e. eyebrows and expressive face. I never included the impact of breeding wolves into dogs have on the human brain.
what having a pet does to a mf
But Australian Aboriginals, Papuans and Andaman Islanders have been isolated away from Afro-Eurasian continent before and well after dog domestication occured and only got contact with canids fairly recently.
I think you mean a symbiotic organism.
One thing we can't measure is the density of the past brains. I do feel like the efficiency is probably very likely . Tightly compact neuron dense. At the same time the female pelvis is getting narrower... Definitely can see all the reasons why
There is no magic. Why didn't it happen in the 3000000 years before and only in the last 3000 years and only in agricultural people's? Nomadic people like mongolians still have 1600cm heads
My guess is we lost our improved hearing, sight and smell because they are no longer as neccesary in an agricultural society. The "If you dont use it you lose it" doctrine.
But does smaller brains mean less skill or less intelligence?
I've heard once, that the size of a brain isn't as important as it's complexity. Like folds in the gray matter or shrinking parts of the brain that are more primitive and not necessary anymore.
we are getting dumber as a species
Einstein has a smaller brain than the average human brain size in his time, despite that his was able to achieve many scientific achievements and predict a lot of things with his theories with his peers, Smaller brain doesn't always equates to less capabilities, rather how healthy and efficient your brain is the outline here
Also, also, here's a man living a good life with only 10% total of normal modern human brain size
ua-cam.com/video/GPWxcTOJfR0/v-deo.html
@Nicholas Time no its all of us. look around you, dumb dumb
@Nicholas Time Got em
Something occurred to me the third time I watched this, is it possible that there could be a mix of actual brain size reduction as well as a reduction in CSF volume? Maybe head trauma was common enough throughout our ancestry that having lots of CSF was selected for because it lessened the damage. As we evolved into safer lives it became less necessary and we began losing the extra fluid as a result. I think we still would’ve lost actual brain matter by virtue of the observed body mass reduction and evident self domestication, but I think neglecting the amount of fluid between the brain and skull during the evolutionary window in question is an oversight.
This is an overlooked theory that makes alot of sense. As the megafauna faded and disappeared, we were no longer suffering as much brain trauma from contending with such beasts. There could of been a selective pressure for higher brain cushioning fluid for millennia as it was probably advantageous to weather concussions and mild-moderate brain trauma more successfully. Good idea!
I really like this idea!
galaxy brain
that's a really good point
True like we have ice now if we hit our head to lower the swelling and medication to help and nothing that dangerous to hurt us humans
“Or maybe you do, I’m not here to kink shame anyone” LOL that was fantastic!
It’s really interesting reading everyone’s opinions and ideas on this. My first two thoughts were: increased density, and a change in diet. Becoming less reliant on meat.
Meat is said to be dense for calories. And he said that the drawback of agriculture is there could be malnutrition. But is that true before 3000 years ago? From the city-state to empires to modern nation-states, the governments seem to want to tax farmers or not give them a good price for their surpluses. I was just reading how Communist-Socialist command-economy governments in Africa implement price controls so farmers can't get a good price for their products, related to the world market. There's danger of that too in a so-called capitalist economy where there's limited buyers (monopolies and oligopolies) for crops and animals.
There was a Sally Field movie _Places in the Heart,_ involving a Black man and a blind man on her farm trying to help her get a good price for her crops during the Great Depression from one local buyer.
@@sandal_thong8631meat is the reason our brains grew so big. Our brains shrinking seems to be the result of grains being introduced into our diet. If the governments have their way we will all be eating plants and man made meats and dragging our knuckles before we know it.
You were definitely correct when you said so called capitalist economy. There isn’t a person alive today that’s seen a capitalist economy.
It's also a microbiome thing. We probably drove most species of our ancient guts into extinction, after hundreds of generations of malnutrition.
I would agree, the ancient human in the beginnings jaws are like twice the size as the modern one, cause they probably had to chew a lot more than we do because they didn’t have any soft foods
@@tman586 I would say the degradation of DNA. We all came from two of our species. I mean look at the pug dog it’s what you get after breeding wolves for so many years. You could never breed two dogs back and get the fantastic animal that is a wolf. You will never breed two humans together and get the tough rugged human that we originally came from. Look to some closed communities like the Amish. There’s one near me that as far as I know have never let anyone in to change the bloodline. They are all little and not healthy looking. Probably no one over 5’ 7”.
I'm an academic linguist. When I first studied linguistics, decades ago, we were taught that language was likely to be around 60,000 years old. I strongly suspected it was much much older than that because of its phenomenal complexity. Later textbooks suggested it was up to 100,000 years old. Nope, I though, keep going. Some of the latest research I have seen suggests that language evolved with making tools, and that it was necessary to pass down some of the skills demanded for tool-making to future generations, and the new hypothesis is that language development (i.e. linguistic signs working in tandem with other linguistic signs to create a grammar - and thus complex meaning - further advanced with simple metaphors enabling the handling of abstract concepts both cognitively and for communication) had its most rapid development with homo erectus, probably beginning around 1.5 million years ago. That, to me, seems far more realistic.
Hi there. Why is the hypothesis that language co-evolved with tool-making? We know that, for instance, dolphins have a pretty good communicative abilities through sound. Would hunting strategies that do not depend on tools but require intense cooperation not also lead to selective pressures for improved verbal communication? Just curious.
@@marcisthabest The technical skills in making hand-axes are considerable. There are issues like selecting the right piece of flint etc and why, what to use to knap it, in what direction/angle and with what force at each stage of its production. It's a sophisticated skill that requires explanation as to things like "why". It means planning - talking about the future and explaining mistakes. That's why the tutor and pupil in the process need not just isolated sounds representing e.g. objects or actions, but also abstract things like reasons and predictions - and for those you need grammar. Without grammar, you are limited to speaking, and arguably thinking, about the here and now. Grammar enables us to deal with relating experiences, explaining reasoning, giving instructions about more than just the immediate future, passing on knowledge stored in the memory, making promises and so on. Or so goes the thinking on this. To illustrate. I can tell my dog he can have a biscuit by saying "BISCUIT!" I can't tell him why he can't have a biscuit, or why he can't have a biscuit, or promise him he can have one in half an hour if he is patient.
@@dogglebird4430 Wow, that it a great explanation/hypothesis! I have never thought about it that way but it makes a lot of sense - thank you for some great food for thought! Have a good day 😊
@@anniestumpy9918 Thanks, Annie. You too!
I don’t think language is unique to humans. Animals may not use words and syntax like we do, but they definitely have demonstrated comprehension AND I’ve personally observed a dog use a gesture to communicate a concept as a symbol, which is alike to how words are used as symbols. Different groups of corvids, whales, dolphins, have unique calls that parents teach to their child that convey messages, and cats and dogs use buttons, and apes have been taught to sign and filmed referring to complex topics with accompanying behaviors and body language related to unqiue new stimulus. It’s funny how we collectively seem so confident yet everyday something new is unearthed that challenges our notions
So basically what you're saying is, humans have gotten as close as we can get to a hive mind without actually being telepathic. We've become so focused on specializing, so good at dividing tasks between us, that we are basically sharing between all of us the brain capacity needed to keep our society running.
If we imagine ourselves as non-human observers, who have no idea about text, it does kinda look like telepathy
Or, science has taken a few ancient bone samples to make conjectures about a whole population of ancient ppl. What if future scientist find bones of today’s basketball men and decide men in the future evolved to be smaller.
Yeah it's like we don't need huge brains because some of the brain power we as a society use is someone else's brain. Kinda like when scientists use multiple computers
@MugenTJ their cranial volume isn't larger though?
@@slvaltva1392 Trust me, people are just dumber now due to technology.
Maybe we have lost cognitive ability in the last 3 thousand years but the collective knowledge we have is so great that we aren't affected by the decrease in cognitive ability in the way that we would expect.
It’s important to say that some sort of encephalization quotient is part of the analysis. This underlies what was mentioned about decreased body mass.
Intelligence over a certain amount just isn't that important to survival.
Look at how the overall population is evolving at the moment.
30k years
That would explain the absolutely massive reduction in average linguistic capacity and reading comprehension skills on UA-cam. The regularity with which people flip their lids at me for things not in my posts is disturbing.
@@KiraSlith there’s a certain point where you need to ask yourself: “if all these people are misinterpreting and misunderstanding my comments, are they stupid or am I hard to read?”
This video is amazing!!! What a great storyteller this guy is!
Personally, I think the 'shrinking' of our brains is essentially how many times our grey and white matter FOLDED instead. I remember reading that completely unfolded, our brains are literally the size of a pillow, which wouldn't really fit inside our craniums! Plus, it takes us as much energy for cognitive thought, to turn on a lightbulb, than the energy is taken for a super computer to solve the same problem! I think our bodies changed to become better efficient.
Nah,the pineal gland is shrinking... We are getting dumber and more depressed.
@@avg_user-dd2yb and breaking the Society
@@avg_user-dd2yb The dumb is from mass media and the depression is from the advent of social media. That's my guess anyway.
@@Alsatiagentyet here you are. 😂
@@helenamcginty4920 gatem
did you just engage in thinking? that was truly a neanderthal moment 🧐
I think the simplest explanation is cranial size and mother and child mortality. Our cranial size got too big, and nature pressured for our cranial size to decrease while maintaining neural complexity.
This is a great hypothesis for this. Haven’t thought about it like that. Quite interesting.
Let’s hope it’s this and not access to ready information. If say writing made it easy enough for our brains to shrink imagine what cell phones will do over a generation or two
Came here to say this. Occasionally razor.
They are studied showing all the csecrions are causing women's pevises to become smaller.🤔
Your point, is well taken. I had an paleo-Anthro prof, who wrote his PhD thesis, on that very point. Cheers from SpoCanada
And this caused us to lose 3 million years worth of brain size starting only 3000 years ago? Not likely.
Ancient man relied on intelligence to outwit prey and other human competition. But now very unintelligent people survive just fine.
With the growth of population and cities and towns there is work that everyone can do. But in the past only those with the best brains survived.
Intelligence is a funny word for simple pattern recognition. The average person learned how to speak and walk so they could be put to work. Any education past that was unheard of in rural areas. Unless you're talking about upper class people. Survival knowledge is knowledge, don't confuse it with intelligence. Wild animals "outwit" prey but you wouldn't say they're "intelligent" just because they're reverting to pure instinct.
You're the best! Thanks for your videos❤️
There is an interesting article by Bednarik (2014, Doing with less: Hominin brain atrophy. Journal of Comparative Human Biology), which has a different time table of the shrinking process (starting earlier than 3000 years ago). But it makes an important point regarding the third explanation - why do we see this process even among hunter-gatherer groups, who do not have to respond to the "pressure" of living in a large society. It is a genuine mystery. Great video, as usual - thanks!
Yeah that’s a problem for any ideas around agriculture and writing etc, not every culture had those until very recently, yet this brain decline seems to be virtually a global phenomenon
A good point. We should be able to see marked brain shrinking with the introduction of some specific aspects of human society.
For example Bedouin herders of today in Saharan Africa experience few if any of the modern technologies/cultural structures that many attribute the modern humanity. Similarly Australia Aborigines live very archaic lives. If these groups also had brain shrink, the idea that it is inextricably link to modern life is very tenuous. We should see precipitous shrinking in groups the the attic tribes in the Americas as they have all but adopted modern society, but did so in the last few hundred years. Is there indications that this is shrinking that populations brains?
I agree, while the timing seems right for allot of the population of humanity, it also seems totally off for others.
There must be other forces at work.
@@macmurfy2jka "Modern life" started literally approx. 100 years ago. It couldn't affect the brain size.
Hey stefan. Thanks for this. Is there anyway of running a CT scan to see what parts of the bain shrunk or was is a overall shrinkage?
I don't believe domestication is a cause of brain shrinkage. You need to have a stable community to start domestication. It's hard to grow crops if your neighbour is burning it down because he's angry at you. So the domestication-syndrome within humans had to start before we started domestication.
I find it hard to believe that language, specialisation of tasks and larger communities are the cause because than you wouldn't have a shrinkage with hunter-gatherers brain size.
If it were driven by external factors you would see a shrinkage at least in some wild animals too.
So i'm inclined to say that it's genome-pheno driven phenomenom. There are things that modern evolution theory doesn't take into account or cannot explain. There are such theories like: evolutionary development biology and extended synthesis but both are still highly speculative.
But it is an intriguing subject indeed
Two further ideas for why brains have gotten smaller recently. One, maybe the the folds of the brain have increased more recently so less overall cranial volume is required. Two, maybe not being in fear of being eaten by wild animals, so having not to be constantly aware and evaluating every sound and movement in our surroundings, has impacted brain size.
I think the latter would be part of the "self-domestication"? But, really, I'd like more comments on your first idea.
another idea:
the human brain has evolved to working more efficiently so less neurons are needed.
Absolutely. If you cut a skull open and look inside you can tell how folded it was and clearly this wasn't addressed.
Brains haven't gotten smaller recently. This video is wrong.
the increased folding is actually an interesting observation, I wonder if anyone has looked into that. If that were the case brains actually did not get smaller, even if they take up less space.
Good video. I was pleasantly surprised. I think it was mostly grains, but that the other 2 things you mentioned may play roles in it.
Great example of intergroup aggression there! Appreciate it🙏
The thing is, there are different parts of the brain. Some appear more to do with "intelligence" - e.g. the cerebrum - than others. The amygdala regulates the fear response - which may not be as necessary among individuals in the modern world. So which parts are shrinking?
Came here to comment something similar, I’m super curious.
If it's the amygdala then why is everyone such a little bitch now? No, as someone who works in tech support I'll put my money on the cerebrum.
Maybe the parts to regulate temperature? This happened since the ice age, and the climate is generally much cooler now than it's ever been. If I remember correctly, we can't physically have bigger brains because we wouldn't be able to cool them efficiently.
It seems counter intuitive though. Would we need more neurons to be able to sweat more?
@@98Zai i really think global temperatures have something to do with this as well.
Earth 20k or 70k ago was a different playing field for everyone back then and what if the bigger brains where required for, better hearing bc there are less animals out there, better temperature control, being more crafty to survive in a slightly colder climate. (Even in the jungles that probably were 2°C colder than now, wich can have a big impact on the wildlife)
The pineal gland too has shrinked, ancients were more advanced.
Some decades back I'd heard a theory that back when humans were hunting large animals and getting battered and tossed about quite a bit larger brain size may have been protective in terms of neural redundancy.
Not everyone was hunting big game though.
@@JonS I think the idea is less about true megafauna like mammoths everywhere and more the general danger associated with hunting using only primitive tools and techniques, even if you are just approaching "normal" sized game.
@@Laotzu.Goldbug right even today more hunter folks die in the woods, being lost, of hypothermia than of being gored or trampled,.... by their rabbit or grouse prey!! ;D
@@JonS Most were.
There's another theory I've encountered which is really similar, and its that earlier homo sapiens had larger brains because more of their brain was dedicated to sensory perception (sight, smell, hearing) and physical activity. And that these require a lot of brain to use. And modern homo sapiens aren't concerned with these things for survival on a daily basis
Our ancestors needed to know and to do so much more than we do need nowadays in our consumer society.
We almost started making a "distributed computing system" of sorts by sharing the professional and informational burden on each individual person , by standing up institutions with central power to control it a little bit as well. And it was so good that we were able to evolve almost effortlessly to reduce our need for all that extra capacity.
My guess is our hardware hit a limit so we instead started developing our software instead, and somewhere along the way some functions in our brain were combined causing some brainparts made for simple processes to be picked up by another part and thus slowly the brain shrunk
Really good point. As far as I know, there aren't many ten thousand year old human brains out there that we can just look at and closely compare
I think that our brains becoming more efficient is the most likely answer.
Our brains "shrinking" THAT much, when our quality of life has only really been making huge improvements in the last couple hundred years? It wouldnt line up in the timeline
Someone should do an analysis on the brains of vegans versus those of meat eats in today's society. It might all come down to nutrients.
@@AFunkyFella It isn't that our brains are more efficient. It is that we became better at externalizing information. You need less processing power when you use more efficient algorithms, but that doesn't mean that your processing power increased.
@@TyrianHaze i doubt there would be any difference, the brain/body doesn't know or care about whether you eat meat or vegan. It just wants the nutrients it needs but it doesn't matter where they came from.
Fascinating topic!
I was doing a research for a video on human biology video a few years back and stumbled upon a few studies that suggested the collaborative component along with the delegation of roles allowed humans to essentially become more complacent (read smaller brain) and eventually evolve into more efficient thinkers and communicators that we are today as opposed to, as you mentioned, fighters and aggressors
Still, we are all wonderful human beings dont you agree?
Hey, Anton!
Evolving to become wonderful persons
Hi, Anton!
It could be the war between human tribes started at the period. The smart ones fight and die as soldiers. The week and dumbs ones ends up having more children survived.
Milo, you are absolutely the best!!!🤩💯🏆
Interesting and very informative. A Max train in the video!
I remember that as a first year student in Biology at the university, we were introduced to this problem and we had discussed about it with different professors and researchers. It is funny that 15 years later we still have no clue about what happened. Your video covered most of the underlying theories very well but there was another theory which was not mentioned here. This theory suggests that during the last 10000 - 15000 years our bodies found a way to make deeper foldings of our brains without losing in functionality. In simpler words we have the same brain power just more neatly packed. This was quicly picked by natural selection as it offers a good advantage (same brainpower but lighter and smaller skull is an advantage in childbirth, balance and many more). The theory overall explains why we do not observe a halt in IQ during those times as you say in your video despite the skull decrease in size but it is difficult to confirm as soft tissues do not fossilize in order to be able to compare the brain foldings of modern people with people who lived 20000 years ago. Maybe in the future we will be able to verify this theory based on purely genetical analysis information, when we have a sound knowledge of which genes are involved in making the foldings in our brain and in what ways for example.
That's an important comment! Thanks for sharing
Don’t mind this reply it’s only purpose is to get your comment higher in the list
As a human with brain folds not as deep as yours, would there not be a need for an environmental pressure to drive this evolution, so as humans with deeper brain folds were to be able to reproduce and pass on their deeper brain fold traits to their offspring while humans with shallower brain folds were not to reproduce?
These theories seen to follow Lamarck's evolutionary theory rather than Darwin's. An innate drive towards biological "perfection" if you will.
What I don't get is why a change as useful as this would have only happened so recently. There's no reason our brains would have needed to shrink to become more neurodense, so the question becomes why didn't our brains stay the same size while becoming more neurodense?
@@donotcare57656 because evolution is as random as you can get
Maybe we underestimate how much brain processing power and size are devoted to things like smell, hearing, eyesite, and sheer physical ability. These abilities have atrophied over time so might have led to shrinking brains.
I think TikTok leads to shrinking brains
@@pavelborisov515 Thats true enough, anyway it does reduces focus span drastically
exactly. and jaws had to be way bigger and stronger to bite through flesh and bone, so it makes sence the whole head will be more powerfully built
@@audhumbla6927 the funny thing about jaw size popping up as an example is that modern studies suggest it has much more to do with diet than evolution, we feed babies soft food now so we don't have to worry about them choking, this stunts early jaw growth. Habits have a lot more impact on your physicality than ppl realize, for instance breathing through your mouth regularly increases the risk for crooked teeth, the teeth can shift while the pressure of the opposing teeth is removed.
@@xxportalxx. i know
Great vid man
Thank you for your work, you offer updated and clear explanations, and nice illustrations too!
Albert Einstein's brain was measured and weighed and it was actually smaller than average so size and intellect doesn't necessarily go hand in hand. Brain size should also always be taken in proportion to body size. Maybe also larger skulls preserve better in the fossil record than smaller skulls which would create a false impression about averages.
I have read that its the connections between the Two sides and perhaps different areas that determined the capacity and intelligence
While larger brain doesn't perfectly equate to intelligence, there have been several studies showing there's a strong correlation. He addressed your 2nd point in the video, he mentions that our brains reduced more than you would expect given our body size reduction
@@rgqwerty63 for example neanderthals had larger brains on average than humans but the larger part was mostly in the occipital region(associated with vision). For it to be more intelligent, it would have to be larger in the prefrontal cortex I think.
reading some of the stuff einstein wrote that doesn't surprise me
@@anonymous-rb2sr can you write better stuff than him?
A explonation i found on a channel called TeirZoo (highly recommend you all watch his videos) is that despite neanderthals and homosapiens being very genetically similar, they were very different and had very different tactics.
Neanderthals were bigger, stronger and had bigger brains, but they also increadibly anti-social, aggressive and only worked in small groups.
Comparativly, Homo sapians were very physically weak and much less durable.
A neanderthal could at least take a few hits from a big animal before dying, homo sapians could not afford to get hit at all.
And HS (Ill just shorten it down for convinience sake) were much more social and often had enormous communites.
And to be effective hunters they had to invent tools like the atlatl or the spear-thrower to increase their power whilst being out of range from larger more dangerous animals.
Despite neanderthals being bigger and stronger, they were the one being outcompeted for food, meaning that their very impressive bodies which required huge ammounts of good to maintain became their downfall.
Some neanderthals intigrated into some HS communities and diversified their gene pool.
Evolution does not care what is the best, it cares what works, and why would it waste energy to change things if it could reduce things and get the same outcome? Evolution is basically lazy, trying to pass a grade with the minimal amount of effort.
Im not saying any of the theories in the video are right or wrong, just wanted to add some important context.
You shortened Homo Sapiens to HS, to save time or energy? You are LB (shortened from Lazy Bastard)
yes! Good point!
Tierzoo fan?
@@eishuno teir
This theory never really made sense to me considering that if we assume Neanderthals were just as intelligent as homo sapiens surely they would've realised that their style of hunting didn't work very well and could've made tools that better fit what they need to survive. But hey ultimately none of us knows for sure
i think all hypotheses are true within each other..
we were/are domesticated by our mercy and domestication made/make us much more coordinated and cooperative that guided/guides us to think on problems together and this effected/effects our production styles and all of them effected/effects us gradually but directly...
and probably our brains continue to shrink due to all these factors...
Hypothesis #4: early humans needed additional neurons to operate more efficient senses and motor reflexes. If you're hunting cave bears with a flint spear you need to be able to sense them (smell, hearing, sight/night vision) before they sense you. Also, having the reflexes of a cat would be a significant survival advantage.
Yeah compared to a more agricultural society that'll hold your hand and give you a prize for being mediocre. Of course we've degenerated some yknow
@@Yamaazaka I reject the idea that intelligence and Brain size is 1:1. Just because some Early humans had more neurons doesn't mean they are intelligent. Cognition comes from how the Neurons interact. Chimps have much faster reflexes and memory recall than us. I guess went from "speedy brained monkey" to "Depressed overthinking human"
One hypothesis that I don’t really see people discussing is the possibility that our brain is becoming more optimized.
At the beginning of our evolution we had a massive increase of brain size in order to facilitate the faculties needed to be more intelligent and capable of working with each other. But now at this stage of evolution we know that difference in brain size doesn’t appear to affect our intelligence. A 5 foot tall woman isn’t necessarily less intelligent than a 6’8 tall man even though the man would likely have a larger brain size. In fact, the inverse can be the case. The 5’ woman with the smaller brain may be more intelligent, but not necessarily because her brain is smaller. Albert Einstein is considered one of the most intelligent people in the modern era and possibly of all time, yet his brain was smaller than average. So clearly at some extent brain size is not an indicator of intelligence.
Synapses can only fire so fast. When we undergo puberty our bodies, including the nervous system, can rapidly grow and become larger. It’s quite common to experience a ‘clumsy phase’ where we’re not acclimated to our bodies. Our brains have to get used to sending messages throughout this larger amount of nervous tissue. Larger people tend to be slower and agile than smaller people (to a certain extent. Obviously larger people have larger muscles and can generate more power). Maybe it’s entirely that smaller limbs are simply lighter and less unwieldy, but perhaps the time necessary for your synapses to fire and make those connections affects this as well, even if that time is minuscule. Perhaps our brains have hit a size limit and making it larger would have an adverse effect on our intelligence. Now it’s seeking to hit ‘critical mass’.
If we look at it from this perspective, then our brains becoming smaller is to shorten the distance between synapses and become more optimized. We’ve seen happen with computers. Allegedly the computers used when achieving the first moon landing had less computing power than a calculator today, but were far larger. This could be the same thing but happening to our meat computers.
If this is the case, it would be interesting to see what the trend will look like another 3000 years from now. Perhaps our brains will begin to become larger again but with more optimized connections and our intelligence could reach new heights.
I’m not a scientist or expert of any kind so forgive me if I’ve gotten some ideas wrong, but it seems like a plausible explanation or another factor to me.
This is an excellent hypothesis!
The distance between the synapses aren't big enough, even in the most outlandish deviant brains, to result in a significant delay. There's a positive correlation between head circumferenfe which indirectly measures brain volume, and intelligence.
Excellent! I agree, seems like most things in our modern world are reducing in size but with greater computing power. The first mobile phones were the size of a house bricks - for speech only but the modern mobile phone is a 1/200 of the size and weight but can carry out many more functions.
The same for car engines vastly more power from the same or smaller engine block.
Einstein had more neurons than the average person.
That's literally exactly what I was thinking about when I saw this in my recommended.
I've seen somewhere that brainpower is mostly influenced by a brain's surface area more than its whole volume. Perhaps our brains have become more wrinkly nowadays compared to prior, allowing for smaller brains with as much brainpower as before?
Sapiens have smaller brains than neanderthals
So basically people back then were smooth brain👽
@@joecar725 Yup, good summary
Nope, reverse darwinism, survival of the most insane and stupid among us, ever see that which is circulating around the internet lately? You'd swear the end of the species is near.
@@joecar725 the best way of explaining
Larger amounts of recent samples would also show any small changes.
If we only have a handful of samples from the past it may be that we had an abnormally large skull throwing off the average from 10,000 years ago.
But personally I think our brain has gotten more efficient and thus doesn't need to grow as large in order to be just as smart if not smarter.
Truly a mind blowing video. I was blown away. Thank you for this amazingly informative and entertaining video.
Mind blowing video 😂
I wonder if the frontal cortex actually increased in humans while the more back part of the brain decreased? Which I think would make sense as hunters needed a lot better visual, motor and emotional (fear, alertness, sensitivity) skills.
Well, that's an interesting thought. Maybe instead of our faces shrinking back under our skulls, the skull actually grew over the face to house a bigger prefrontal cortex. And the back shrank as we lost the need for instinctual behavior, thus shortening the back of the skull.
It makes sense in theory based on the points you made. And it makes sense in looking at the skulls.
Btw, my kitty's name is Marina. Well, Marina-Bunny, actually. 💖🐾💖🐾
Maybe that would explain the rise of mental illness?
(Im genuinely open to being corrected)
- a mentally ill person
@@anyascelticcreations yeah, exactly! The skull looks smaller and smaller at the back and bigger in the forehead area
@@anyascelticcreations that’s so sweet. “Come here Marina-Bunny!” 🥲
The consensus view among us neurobiologists is that the reduction in brain size is due to ongoing selection for greater neural efficiency essentially doing the same with less. Impacts of diet change etc are seen as a secondary support for doing the same with less. Ideas about society complexities are seen as no required to explain the phenomenon and rejected on a Occam’s Razor basis. The overview view is supported by large changes in dietary related genes occurring across the same time period showing that diet (and disease) have been the major drivers of human evolution over the recent past.
Wouldn’t ‘doing the same with less’ also not constitute that we would not need to have all of our senses active at the same time? Being able to focus one one thing at a time, not having safety in mind all the time, not needing to use the body actively to do complex tasks would enable the capacity for more deep, singular concentration.
That doesn't seem like the simpler explanation to me. Maybe the neurological explanation only seems simpler to you because you're a neurobiologist. I would think that positing brain size continues to correlate with intelligence as it always has is simpler than to assert that this is a special case with no special cause.
@@rq9jgbbv386 but the Homo Floresiensis case shows brain size and intelligence doesn’t have to correlate.
@@ivarbrouwer197 good point.
Somebody called me a smooth brain, what does that mean?
Great video... subscribed. I agree with hypothesis 3. I would also like to know if there is any data on the amount of wrinkles in the various brains throughout these stages. More wrinkles add more complex thought capability. So a smaller wrinkly brain has more high-level brain power over a larger but smoother brain.
As for the future, I firmly believe that we will begin merging with AI implants. More like a neural link setup that allows for constant communication through exterior devices. That also allows for much easier upgrades without requiring any additional surgery. Consider what it would be like to have all of mankind's cumulative knowledge pulled up as easily and clearly as you pull up a memory of something you studied in depth for years. Also, think about how most of us have that internal monologue we can bounce ideas and thoughts off of and even debate with it. Now imagine having a third voice in our heads that is a super-intelligent AI that can be accessed when we want and then shut off when we don't. While I wouldn't want to be an early adopter, I would be completely onboard once the tech has been thoroughly tested.
Ads in the sky
@@gregoryturk1275 I would definitely NOT want anyone else to have access like that to our implants. That is the largest risk.
CPUs & GPUs are getting more and more powerful while have lower and lower NMs, maybe it's the same with us, getting more efficient and more powerful.
I'm a retired professor of psychological anthropology. For various reasons, I've made a complete break with academia and the current state of issues and debates in anthropology broadly. I just wanted to say, it is encouraging and delightful to see that anthropology is still being taken seriously and pursued as an holistic science. You do a good job of synthesizing the issues surrounding this topic.
elaborate a little on those "various reasons". are they of a political nature?
@@tylerprudhomme Of course ;)
Same issues plague environmental sciences
Breaks the heart...or mind
Yeah, anthropology will always be taken seriously by me ever since the days when I as a young child was digging daily in the neighborhood garbage/trash/rubbish/midden dump of my shantytown.
I started my scientific exploration of anthropology because it's easily available, not because I was egocentric. I dug up a modern marvel of a bicycle dynamo which attracted ferromagnetic garbage.
@@kingstonsteele7820
Could it be due to the Trumpery manifested by the Don's majoring in Anthropology in 不周山大學 ?
I wonder what we lost? Or were more things hardwired, rather than having to programme our brains with learning only the things we need for our specific environment?
Well if the last hypothesis is to be believed we haven't lost anything as such but individually we're just taking less of the strain. We're able to solve problems together better.
@@StefanMilo perhaps it's like going from vacumn tubes to micro chips - just more efficient.
@@floydt2029 a brain patch
@Hokusai birds being a great example. Their cognitive abilities (particularly corvids) is astounding given their small brain volume. Obviously when you fly, a more efficient brain architecture has huge advantages.
@@JonS so basically we're gonna grow wings?
Ok... The quality of this video is something else. 👏👏👏 The concepts also are extremely amazing. Maybe one day we get to have stronger brains by adding chips and micro electronics to enhance our brains?
It’s possibly due to widespread usage of written language which drastically reduces the need for memory capacity, not just with data but also with problem solving metaphors historically stored in the form of stories
I’m not a scientist and I’ve probably missed some important point here, but hypothesis number 3 doesn’t seem to explain why the brain size of Australian aboriginals has also decreased over the same time period. It looks as though their culture and lifestyle has probably been stable over a considerably longer time period, they did not start using agriculture and living in cities, so how to explain the decrease in their brain size at around the same time as humans who did do so?
Sorry if this is a silly question.
Oh, the same query would apply to the self domestication hypothesis wouldn’t it?
I don’t know, I’ve got a very small brain and it’s very late at night, but I’d be very grateful if some kind clever person could tell me where I’ve gone wrong in my thinking here.
Survivorship bias or luck related to finding skulls.
Only 23 Aborigines' skulls were present in the P. Brown study which is referenced by this one.
Furthermore, a lot of non-sceintists these days are intensely arrogant with their trust in 'science', even more than God.
Unless you delve into the research papers, reading everything and every citation and going through the history of the researchers and then confirming the study, what's more likely is that you're on top of flawed studies. The modern scientific infrastructure is incredibly bad. I wouldn't be surprised if all of this video is completely wrong due to the data it references (although domestication syndrome does have significant evidence).
Check out Vertasium's video : "Why most published research is wrong". He covers most of the main issues there.
Any popular media based on science... It's better to assume it's wrong than right. You'd be correct more often by assuming it's wrong.
Naturally, science is good but the current infrastructure... It's closer to beleiving that witches exist than most realise. Like most of modern society, it's incredibly shallow.
And even ignoring false data, there's a higher level of competence assumed than is present. Evolution isn't my specialty so I will tell you something regarding what I'm semi involved with. We don't actually definitively know what causes male-pattern baldness. Yes, really, something as common and (arguably) significant as that.
The title's actually "Is most published research wrong", rather.
Well there is evidence of Pseudo Agriculture and most Australian Aboriginals today most likely live in cities and live like the various other Australians as a result.
@@tauempire1793 Good point regarding agriculture (probably) being present. Although the fact that natives live among European-Australians in cities is irrelevant. As that's not long enough to explain the decrease in brain size (which may or may not be real).
I think you shared a very interesting point. Stefan could do a show on your comment. I suspect a thorough examination of Australian Aboriginal genetics will shed light on the reason. I suspect that reason is an influx of Homo Sapiens into an already occupied Australia of earlier ancestors. After all, we all are hybrids of types of people....no matter how pure we think we are.
What if the Romanian skull came from someone with a genetically large skull in comparison to what was average. As far as modern humans, you can find examples of people with larger than normal skulls.
think about it: what if the brains are actually growing bigger?
true, basketball players have enormous heads. Maybe Romanian man was 5,7 feet high, there is no rest of the body.
Is everyone forgetting that this romanian skull had its dna analyzed and has revealed it was a 6th generation human/neanderthal hybrid?
@@francorepici3586 40.000 years old usable DNA in a specimen that's not been frozen? Dream on princess 🤣
400,000 + year old dna was recovered from pre neanderthals in spain.
One interesting difference between human and chimpanzee brains is that chimps easily outperform humans in some short term memory tasks; for instance, they can remember the spatial arrangement of numbered dots, the corresponding number being briefly flashed on a computer screen, and they can sequentially press these dots, once the number designation has vanished. The amount of brain devoted to spatial, and other short term memorizing capacities, might have atrophied in stages.
It would be interesting to do a study on brain size affecting IQ in modern people. There must be a slight variation. I suspect something else is going on.
What do you mean exactly?
Intelligence is a very complex topic that IQ doesn't completely cover.
It is very possible for a very nimble person that is highly developed in sensory-motoric coordination to have more neuron connections than an average person that would be focused on higher cognitive functions but has underdeveloped sensory and motoric functions.
So the latter could still have a "smaller brain" because much parts of the brain aren't focused on the higher cognitive skills that would be measured in IQ
@@LalitaLunaYogini
Brain size still has a correlation of 0.41 with IQ, and generally, developed cognitive abilities in a specific field correspond to developed cognitive abilities in general, so someone who excels in one field will therefore would still have above-average skills in all other fields…the so called “savants” aren’t common and are basically just associated with autism.
Intellect (consequently, IQ) and brain size are indeed positively correlated with coordination.
Although IQ isn’t a perfect unit of measurement of cognition in general (and such just can’t exist), it is strongly correlated to the general factor of intelligence and provides all the relevant "predictive" ability of intellect.
Intelligence is not exactly the same as abilities defined by cognition in general though, but more: “the ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly and learn from experience … a broader and deeper capability for comprehending our surroundings - making sense of things”.
I talked about cognitive abilities as a whole just because it still works by considering the generality of cognition.
@@LalitaLunaYogini Wrong. That doesn't even make sense. Intelligence means intelligence. Not physicality.
It has no correlation in terms of intelligence what about birds that have smaller brains and beings that SHOW much more intelligence but have no brain at all?
More fauds in the brain, higher white matter concentration and neural connections matter more and have shown to impact brain work than a size of a brain.
Based on ancient literature, we might have an explanation. I'm particularly curious about the power of memory, here. It was, apparently, common for ancient Greeks (around 3000 years ago, curiously, just before the brain size decrease) to memorize the entire Odyssey and Iliad, and perform these 200 thousand word books from memory, something that modern humans find to be much too difficult to do; yet, in a pre literate society, you'd need to have a memory like that in order to learn these stories and pass them down. When they finally wrote down Homer, this corresponds with the time that human brain size finally started to decrease. This might have been driven, largely, by writing, which made it no longer necessary to have such a good memory and memorize every detail about everything. You could write Homer instead of memorize him, and so, people stopped memorizing him.
It's funny to read contemporary people of those times complaining that things like writing were going to "make people dumb" like our grandparents talk about TV or the internet. Looking at the internet it seems to be a confirmed theory LOL
The timing is interesting, assuming you're correct about that, however I doubt very many ppl were memorizing massive amounts of knowledge prior to education becoming accessible. The Greeks you mention were in the minority lucky enough to have access, generally through wealth and status.
In any case this seems easy enough to test, just look to see if ppl with eidetic memory have larger brain volumes. That data probably already exists if you look for it.
The thing is the common people didn't do that, it was only the upper class, everyone just learned their trade and moved on.
@@macmcskullface1004 yeah I thought of that point too, however the exact timing of the reduction isn't given for different places, that 3kya figure is just from that one study of like 900 skulls, you'd have to look into the paper to find out what region they had samples from. This gives a lot of leeway (without actually looking into the paper) as to when different regions changed. Besides that 1000 skulls seems a touch small to me to draw conclusions about the whole of the species anyway tbh.
The main issues with that theory are that storytellers were a very small portion of the population, and several cultures still have oral storytelling tradition to this day.
1:58 “cultural achievements”
>shows a McDonalds
💀
Good video. For those interested in this subject, Tina, at 'Curious Being', did a very good video on this. A couple of them, in fact.
I take it another way. Not every part of the brain is used for memory, cognitive ability and problem solving. The brain is used for everything, coordination, vision, hearing, sight, sensation, emotion. We may have lost brain matter- but that gives no indication of what that brain matter was used before. It very well could have been holdover matter from a previous evolutionary niche we simply didn't need. For instance, chimps can instantly identify numbers on a screen faster than any human can hope and remember them, we simply have no need to, however, as picking out potential threats in a split second is no longer essential for our day to day survival. I think it's far more likely that the parts of our brain devoted to complex thoughts are increasing, and parts devoted to immediate survival from predators, aggression, and others like them have been decreasing.
I'm not surprised people recently lost a whole lemon worth of brain tissue. I would've guessed even more than that!
Not people. Women
@@SeregaOrgan Lmao
@@SeregaOrgan well woman do loose braincells each time they have kids. I was reading something about this a few months ago. Not sure if it's true. But compared to our ancestors are brains are not designed to handle stress like we used to, especially woman because life has become extremely easy compared to 50, 100, and so on years ago. So we don't need certain parts of our brain to be as big.
@@SeregaOrgan I mean, buddy...
You seem pretty stupid too, to broadcast this to social media, where opinions exist to be argued agains (no matter the validity).
@@SeregaOrgan women have smaller brains than men
I think 40,000 years ago people needed a wide variety of survival skills in order to survive, but as humans started forming more organized communities people could depend on each other for survival.
Exactly. And they developed both technologies (different crafts, reading and writing, governing systems, etc.) to which they outsourced their survival. With the result that no contemporary human is remotely self-sufficient, or survivalworthy.
collective knowledge
Humans probably shifted into abstract thought patterns using symbols around 40,000 years ago requiring less concrete data memory.
I compare the development of smaller human brain size to the development of client-server computing in which the clients became highly application specific and more energy efficient in manipulation of higher-level symbols.
Before the client-server computation model, the mainframe computers got bigger and bigger to tackle more and more complex problems. Once the client-server computation model had arrived, *FACTORIZATION* allowed the complex problems to be solved by simpler processes in a client and in a server.
2 times 3 being greater than 2 plus 3 is the reason that the factoring of tasks is more efficient for tackling a larger set of problems.
That has no bearing on brain size. That is not how evolution works.
More organisation and bigger communities requires MORE social intelligence, not less!
@@JohnDoe-et8th Sorry, but solo survivability is not connected to intelligence. In fact the more sophisticated a society becomes, the more intelligence is required to be successful in that society.
Today we recognise that people with IQs below 85 can make no meaningful contribution to society, because there are no jobs they can do which doesn't create more work for other people. This is a fact.
And as society becomes more and more complex, that number will rise as the Singularity approaches.
Two speculative possibilities: 1) while brain size decreased the complexity of dendritic arborization increased - I think human brains have seventh-order arborization; 2) a reduction in muscle mass including a reduction in the number of motor units, which would result in a decrease in the size of the frontal and prefrontal cortex. But these are just guesses.
I think it's the 3 listed reasons. An age old saying: Use it or lose it.
If we don't have to think of hunting and gathering.
If we don't have to think about predators.
We lose the aggression portion of our brain. It's like how an appendix isn't actually "used" anymore and we can live without it.
Honestly wouldn't be surprised if in the future more children start being born without appendixes. 1 in 100k surgeries for appendicitis actually found an absence of the appendix but an inflammatory mass was formed instead. (Some other infection, I imagine.)
With a sample of only 900 skulls I wonder how true this is. Maybe, a robust larger skull is more likely to survive in the ground. Maybe the decline in skull size 3000 years ago had more to do with burial practices and how it affects skull deterioration than actually representing a change in skull size in the population. It’d be interesting if someone has done the same study on wild animals to see if older skulls in the record have a tendency to be larger.
Survivor bias
my calculus doesnt show your hypothesis as signifcant
Yeah, I'd prob have to read the paper to see how they accounted for variables like that. But it isn't a great sample size for like the entirety of humanity
@@kyrab7914 nah u dont. Geologic pressures should be largely the same across all skull densities
@@jennytalia6724 ... It's not just geologic pressures. As the original comment pointed out, burial practices could affects fossilization. Basically everything that affects fossilization has to be taken into account, and that's a lot of stuff.
It’s possible that due to the sheer variety of animals, plants, and other such survival things that early humans HAD to know to survive, we needed a more developed neo cortex to store long term memories
@Damon Edrington,
I think you've hit on a major reason; our memories HAD to be cue'd by different sensory input. We once identified edible plants and fruit by taste and odor. Now, we utilize our information about food differently, tying into cultural "norms" (i. e. cultural tastes vary tremendously - salt, sweet, spicy and bland palate choices).
We don't depend upon storytelling and song to remember our history, either.
I could identify and differentiate between my infant children by their scent, and could tell if they were sick because their odor changed (yes, I bathed them daily, lol).
I think we've lost some knowledge because the information we used is no longer part of our daily repertoire.
No. Life today is FAR more complex than it ever has been. In the bad old days, your life was identical to you father's, and his father's, and his father's... There was bugger all to learn, and life was simple, if not easy.
@@Chris.Davies Life was not easy back then, we were damn near extinct there for a time. You try living of the land for a year without ANY modern tools or electricity and tell me how easy it is. I would be willing to bet you wouldn't survive.
It's true our society now is more complex but that doesn't mean our brains are more complex.
We're all just cogs in the machine, just because the machine is complex it doesn't mean the cog is.
@@Chris.Davies some people argue because they think it makes them look smart, when really it doesn’t when their argument has no substance…..you are one of those people.
The quantity of information a moder human ingests is FAR more than in any point of history and prehistory
My comment is not too much about brain size but about getting smaller depending on climate.
I remember from school time, that vikings were tall. Today, we are again near the same size. At the start of the little ice age, we (Danes) grew near 20 cm smaller due harder climate and thereby food supplies.
Cheers Niels
This is a thought provoking video. I am a little surprised that, in this age of neuroscience, neurological changes were not considered. For example are our brains more neuron dense compared to say a chimpanzee? Are our brains 'neurologically 'better wired' compared to that of a chimp. Given that aggression is predominantly a limbic process then less aggression need not correlate to brain size, what else might have been going on?
A neurological perspective is essential in getting a better understanding of this issue.
Still a great video - Thank you.
Remembering all the plants, all the animal, all the weather, all the skills is such a toll. Agricultural, Industrial, and digital revolution makes us specialized, thus kinda making our brain work easier
Maybe we are evolving to a "hive mind."
@@JadeDelphi women lost their brain size cos of feminism. this caused females to not have to think about anything except how to whine and complain. This is why females have small heads.
This also affected males badly, because they partially inherit the weakness of females. Kind of like how some women have hairy legs... simply because males do too. It harms both genders... but the cause is basically feminism.
@@JadeDelphi imho modern society is an hive mind
In addition to the factors you mention, diseases are a more important factor for agricultural societies than for hunter gatherers. The selective pressures for stronger immune systems may have been significantly stronger, perhaps leaving less “room” for brain size to also be selected for and therefore maintained.
It's because life has gotten easier.
We don't have to hunt or build our shelter.
We don't have to create our own tools.
Everything is done for us
Again size doesn't equal more intelligence.
This contradicts a study from the University Of Tennessee that says there has been a growth in the size of our brains and changes to our skulls. Our skulls are said to have been growing taller and narrower and less round.
I guess my question is, to what extent is brain size actually correlated with intelligence? Because crows have much smaller brains physically than cows, but are obviously much more intelligent and capable of problem solving and tool use. Is this perhaps more of a reorganization rather than a "loss".
The brain mass dosen't play as much of a role in inteligence. I think the amount of neuro transmitters in the brain does, and thouse can be squished into really small spaces. There was intresting case of french clerk "without a brain", you can look it up. This man wasn't really brainless, but his brain just went through weird reduction after some neuro surgery
This is not about comparing species...
people with higher iq in general have bigger brains
@@dreaming_butterfly1970 then blue whales would study quantum physics
@@schlaubischlumpf211 i am talking specifically about a certain ape species
So 3000 years ago they started shrinking drastically, right around the time metal work started ramping up. I wonder if the brain toxicity of certain metals like mercury and lead and just the general use on industry had an effect
Very interesting.
How does exposure to metals alter DNA in such a way to produce smaller brains? That's a weirdly selective poison.
Interesting idea but would that be true for the Australian aborigines or other isolated hunter gatherers whose brains seem to have started shrinking then, too? Something to ponder, though.
All metals are toxic as you appearantly know. Even iron in sensitive individuals.
But usually that kind of toxicity will reduce brain abilities too and that has not happened. Plus it happened to Australian natives as well as American natives.
7:38 wow bro, where did you got this sepak takraw clips. Its seems rare and authentic
Also the compound meat proteins added to the increase caraineal capacity it's almost as if they were helped. And when you ignor the help. You get a diminishing return.
I will give my theory. It is related to self-domestication. I believe that as humans became more "civilized" they started to live in larger tribes or communities. This in turn meant that enough people lived in close proximity to be able to specialize tasks they needed to do to survive. Think about it. If I am living in a small family unit of hunter gatherers, I had better have the smarts to be able to make tools, find game, bring it down with little help, and cook it and eat it. I must also be able to survive the cold by building shelters and making clothes.
Now, suppose I am living in a Neolithic village of several thousand people. Maybe I only have to know how to scatter seeds for crops. Building houses? The whole community works on that. Hunting? A lot of us get together and figure it out. Making weapons? We have a couple of guys in the community who are really handy at making bows and arrows. And so forth. In a modern world, one only really needs to know how to do their job and to please others. Just my thoughts.
I would think even small groups had specialties tbh. The scale def helps, but if you think about it, even in modern nuclear families, we specialize. Say someone's better at cooking or cleaning than another. I think it's likely that everyone in the group would know those things, but Urga might be better at tool making than Steve.
"If I am living in a small family unit of hunter gatherers, I had better have the smarts to be able to make tools, find game, bring it down with little help, and cook it and eat it. I must also be able to survive the cold by building shelters and making clothes."
You do have those smarts you're just not taught them.
only works if families are kept seperate of other families and the families specialise in certain tasks
if everybody could decide to specialise in any task, it doesn't work
@@marc_frank if you think about it, that's how many families worked before the industrial revolution. Maybe even a bit after. Your father was a farmer, so you're a farmer, or a blacksmith, so now you're the town blacksmith, etc. It's not unprecedented, but being that it's the past, much harder to tell
@@kyrab7914 true
i think the general groups farmer and blacksmith and similar involve a lot of tasks
I am as curious of how reduced brain size was uniform across all human societies around the world 3000 years ago. Think of the variety of environments, cultures, and food types available, so many unique that those groups of humans.
Aliens. It always comes back to aliens. Lol. 👽
It’s the similarities, the processes of creating a safe and dependable environment: the tools/parts might have been different, but the solutions the same.
Maybe it's atmospheric industrial off gassing
It wasn't uniform across all societies. Not all societies in the human family are equal in advancement, nor have races been granted the same gifts.
@@markov886 the video by Milo clearly states that the brain size reduction was present across the planet, as he quoted several instances from Europe, Asia Africa to aboriginal Australia. Making it unlikely to be this about different stages of cultural advancement: it’s either behavior we changed almost collectively as a species or a purely biological phenomenon.
My dad had a job on a farm/ ranch and he said those brahma cattle will kill you if you don't keep an eye on them.
I hypothesize the decrease in human brain size is the result of the division of labor. Larger brains are required for people who must know how to do all the different tasks one needs to survive . On the contrary, people who evolved into specialists, who focus their work in one industry do not require larger brains.
In this way, paradoxically, humans have more brains from the increase of human brain interconnectivity. It seems a 10% shrinkage is more than compensated for when a group of humans specialize in different industries, working together to ensure every human receives what it needs for its survival. I suppose this adages such as "let's put our brains together" and "two brains are better than one" originated from this.
Apes together strong
Genetics haven't changed that much in 3000 years so I'm thinking this relates to the poor diets of ancient farrmers.
It's like computers when they were the size of whole rooms, we have made them much smaller and much more complex since then. As we found better ways of making computers. Couldn't our mind found a better way to operate without needing as much space
no it is when we invented netflix and tiktok... that decresed the size of our breains.
except the tiktokers
Our brains are not more complex than our ancestor’s. But we like to think so.
13:30 There really seem to remain a lot of inaccuracies in our picture. 10'000 ya and 3'000 ya as a turning point are quite a difference, especially considering the apparent or supposed correlation of the effect all over human populations, living in all kinds of different environments and cultural configurations, which is probably the most fascinating aspect of this for me.
I was similarly assuming greater efficiency in the streamlining progress over time and environmeny. So 1,2,3 are all good, but 3 especially. Thx.
I love the self-domestification theory, really turns 'survival of the fittest' on its head
Only if you don't understand what survival of the fittest means.
It fits completely into survival of the fittest just fine.
The switch from fittest alpha, to fittest team
'Fitness' in 'Survival of the fittest' does not mean what you think it means. It means 'I am fit enough to socialise with people', 'I am mentally fit enough to work with the team', 'I am physically fit enough to protect others', 'I am fit to be chosen for this role', 'My mind is fit enough to defend you in Court', etc.
Also, look at that protection one. Fitness to protect the family/team/etc allows other members to survive/thrive, and be fit to do their own lines of work, to recover, or live a good life if they can't/can no longer be fit in a field. Like making armor, or creating board games for your mental health. And one day they may protect you, when you want to change fields, or when you grow old. Flexibility in the the group, no?
Tho, money has reduced the need to grow super strong bonds if you don't want to. Exchange of services and goods, and all that. Extra flexibility, and ability to move elsewhere.
What if some advancement made us lose an aspect we’re not noticing? Like maybe our memory is actually much worse due to written language? Less pressure to remember.
That is a possibility as we changed from an oral-tradition society to a literate one. But literacy became universal much more recently like in the last hundred to two hundred years. So something else was going on 3000 years ago; perhaps warfare?
I wander about the lack of instinct. People used to have a much better ability to not die. People often say we've lost "common sense" perhaps instincts take up a lot of space lol
Humans were starting to socially dominate others for leadership positions around this time, due to larger teamwork projects and cultural information retention.
This leads to domestication of ourselves because whoever wants to be in control of many other people tend to want people easier to control in order to accomplish those projects.
Amazing the second law of thermal dynamics still holds true. But then it's always been observable.
Very interesting. Thank you. Another dimension of this matter that occurs to me is that, with civilization/domestication, less demands are put on our senses-hearing, eyesight, smell, etc.- so that the amount of brain energy required to engage those diminished senses has decreased, resulting in smaller brains.
That's one thing I was wondering if certain areas shrunk more ect. Also with specialization, ect, we each need to learn /apply less in our everyday lives to survive, so between those two, plus possible more efficient functioning of our brains , could all make a difference.
This is what I think has been a major contributor. Our eyesight, hearing and especially smell is no longer as acute as it had to be 100,000 years ago in order to survive
If it had occurred during the transition from hunter-gatherers to agriculture and domestication then I'd agree. But it seems to have something to do with civilization 3000 years ago. Of course it would be interesting to find out if places in the world without cities had reduced brain size, too? Let's say they did, then perhaps organized warfare was a driving factor rather than careers outside of producing food.
We don't have to hunt with spears and bows and slingshots for our daily food anymore. Nor do we have to escape large predators in the wilderness. So we don't need those acute senses
I've heard that the amount of chewing the modern human does is much less than that of our ancestors, and this effects mandible size during development. Possibly it is also making the rest of our head smaller, with the brain size shrinking just being a necessary side effect?
I mean I agree with the fact that chewing has had an effect on our skull. It can not explain the size difference of the brain though
@@crabb9966 Ah like maybe because the skull is smaller the brain has to be smaller to fit? Not saying this is true, so much testing would need to be done to answer that. Just speculation
@@tryfanevans7047 This is definitely possible; our faces have become less robust overtime and this is because there is no evolutionary pressure to have big skulls and jaws, the jaw part is due to less hard chewing and our faces are not as robust as there is less war and hunting where you have to survive by having a big skull. When they study skulls from 100 000 years ago or so they often see hints of heavy blows to the face.
One of the primary questions is the correlation between the volume of brain tissue and cognitive ability. If there is little reduction in the latter then the decrease of calorific consumption would be a major suspect. The selective processes responsible for the reduction in cranial capacity in homo s. seem to derive at least in part from a form of self-domestication due to social/cultural expedience. Just for fun see Balyaev's experiment of the domestication of foxes.
certainly domesticated to an extreme degree, and perhaps by an unseen hand (by definition, the sohistication of our domesticator's tools go unobserved or at least unappreciated as such, and are likely to be beyond our general perception so that they are actually effective).
Love the book, I got it for my son and gave it to him after I read it lol. I'm amazed with the value of your content. Thank you sooooooo much for keeping our curiosity alive, my son, my last and I love your videos. Keep it up, and thank you for sharing what you've learned from you're research and she your passion. We will keep absorbing it, and will watch your videos for as long as you make them. Absolutely fascinating, and so much fun to ponder all the subjects you discuss. Thank you again.
Hey thanks man, it means the world to me that kids are enjoying my book. When I was a kid I would read history books constantly.
👋🖐The Connections (2021) [short documentary] 💖🙌✌
Surprising I remember noticing that Roman helmets looked incredibly tiny and always assumed we have gotten bigger. Maybe it comes in waves based on nutrition and region.
Its because romans where smaller as a whole not only their heads, and yes it has a lot to do with nutrition and also they where latin and we tend to be a little smaller than germanics so there's a variety of reassons why you may see their helmets as being small
This suggests a different point to me actually. The very intelligent may have risen to the top of society way back then, and were buried with the most care and the graves were honored. The commoners however weren't that bright, and were buried in common ways, therefore we don't have access to their skeletons. Romans BTW remember were mostly cremated, so all we have to go on now is probably their armor.
Due to diet and lifestyle we'd be considered giants to the people of that era.
Yep the Templar knights armour in Malta tells us the knight were ALL under 5foot. Like 4"6. Hilarious in a nation with myths of "giants"
Your brain isn't just used for "thoughts", it's also used for movement. A bigger brain is needed for more muscle mass (e.g. whale), simply. It's physiological and not "archeological" I guess so the presenter doesn't pick up on this "possibility" I think. If you can get away with a slow body that doesn't require much food while chasing down prey with a long range "aim assist weapon", you don't need to control the muscles to climb trees and propel a giant body to maneuver and stab something...or someone (in "societal" organized conflict or otherwise).
I go for change in diet, less fatty animals like mammoth etc and more carbs not available in the wild . Maybe other factors like using our senses to hunt also may have played into it. Basically agriculture arriving has the largest effect in brain shrinking but gave time to learn.
The average height of the Chinese has increased with more meat in their diets so it does matter.
No kink shaming here 😂😂😂 Love ya Stefan 😂
Just as tall trees causing a giraffe to stretch their neck doesn’t result in the giraffe species getting long necks, the lack of need for remembering (due to writing) or lack of need for knowing everything (due to civilization and specialization of work) would not reduce brain capacity. There has to be a pressure against big brains.
Pressure could be -
Societal pressure- Big brained teenage aggressive brutes were easy to eliminate by society after weapons were invented and didn’t pass on genes (hypothesis #1)
Environmental pressure- Big brained babies suffered loss of life while child birth and did not pass on genes. Perhaps because the mothers were getting smaller due to change in diet after agricultural evolution or lack of food in younger dryas or some other pressure resulting in smaller women. Note megafauna also perished around younger dryas. Was smaller brain capacity observed in other surviving mammal species like elephants around this time? If yes it could bolster this hypothesis.
The thing is just that there is a constant pressure against big brains, and that is its massive energy consumption. So unless there is pressure for big brains to develop, there will be pressure against it. With this knowledge in mind, there are a lot of reasons that could partially contribute to our decreased brain size:
Theories include things like higher neuron density and better brain folds making the cognitive parts of our brain keep up their performance despite the shrinking size. Or more primitive functions of the brain get downsized as they become less needed(i.e. sense of smell, instincts, situational awareness: these do take up significant parts of the brain).
Also smaller brains mean slightly faster processing of information, so slightly better reaction times. Or the reduction has to do with not needing as much redundant brain mass to survive head trauma, meaning due to less frequent attacks on our heads as society kept us safer that extra mass was shed.
Reproductive pressure - less intelligent people are more likely to have children and more of them?
At least this last point can be observed in present society, poor, unsucessful and thus presumably least intelligent people have on average the most children. Perhaps when society got advanced enough that stupid people were able to survive and reproduce just fine (3000 years ago?) the selective pressure for being smart largely disappeared
@@nsk370 That is a phenomena IMO from last 100 years when more educated people control their reproduction. Also the point I think he makes is small brain didn’t necessarily result in dumber species. IMO the progress humans made during small brain era (last 10,000 years) is much faster (even using logarithmic scale) than the progress they or cousins (Neanderthals) made in 300,000 years before.
@@tolbryntheix4135 Trying to find hypotheses for a sudden brain size change. There may have been a constant pressure on big brain - like you suggest - for last 300K years. But it appears there was a sudden change around 10000-15000 years back.
Lamarck wasn't entirely wrong. Epigenetics are a part of the picture, along with physical evolutionary pressures.
I was told by one prominent anthropologist that out modern day overbite is a phenomenon of the last 1000 years. The skulls of Mayans before this time have an almost exact line up of jaw and upper teeth. Today we have a slight overbite absent up until then. So it may be possible that many universal slight mutations are taking place. Like our appendix not being useful any longer.
Dental alignment issues and oral shape problems both correlate to a modern diet -- requiring much less chewing work and typically featuring a lot of sugar and soft food -- and are virtually unseen among modern populations that still stick to traditional diet, such as various Asian and African rural indigenous groups.
@@notashroom Hey, on that note I found out from an anatomist at a lecture one evening that modern humans have a slight over-bite. But, this phenomenon has only been a common trait for only the last 1000 years or so. This means we're still slowly evolving physically.
@@WmGood when we stop evolving, that will be the beginning of the end of humans. I would not be surprised if the modern diet was behind the overbite trend, too.
The idea that the appendix is a vestigial organ was long ago debunked. Very few animals actually have an appendix, and there's no evolutionary "source organ" to explain its presence. All of the great apes and most monkeys have an appendix that is no different than ours.
It's more known to be an important immune organ that is most active during childhood, desensitizing the immune system to good bacteria and antigens in food. Later in life it's known that it LOCALLY stores beneficial gut bacteria whilst LOCALLY being very effective at suppressing harmful gut bacteria living in its little pocket. When a severe intestinal illness sets in, bad bacteria often out compete the good bacteria so the immune system blasts the colon and kills most everything. The appendix then acts as a reserve to repopulate with good bacteria.
Modern heigene and medicine have allowed us to live without an appendix as an adult, but its childhood role is still considered essential.
When we domesticated dogs they equally domesticated us. Its not really about one group domesticating the other, it is about both adapting to a new easier lifestyle where they combine their strengths and cover each other's weaknesses. It gave this team a huge advantage over the other animals, and the rest is human history where we dominated (and kind of destroyed, as a result) the planet. But in forming this union we changed into different animals, now ones adapted to be in this symbiotic relationship with relaxed pressures.