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The human brain grew as a result of the extinction of large animals: new paper
- airhead969 6y agoYou don't chase down most little critters, you bait and trap. That does require being less of a dummy.
- tashoecraft 6y agoInteresting. Wonder if this conflicts with the idea that human brains grew as a result of eating more meat. That instead human brains grew due to evolutionary need of harder to catch meat sources.
- bazooka_penguin 6y agoNot directly related, but I find myself to be mentally sharper when hungry, if on edge a little.
- airhead969 6y agoAs protohumans and humans invaded lands, they likely extincted megafauna and flora calorie and protein sources that were easiest to access. This then likely required more mental effort and creativity to solve food security problems with hunting and gardening.
- tashoecraft 6y agoIt's interesting as it's a common argument that "meat caused us to have big brains, meat good", but that analysis might not be so clear cut. If this paper is right it may be more of the search for meat is what caused our brains to grow and less so meat protein.
- marshray 6y agoIt seems nonsensical to me that simply eating meat protein could somehow cause a genetic change leading to great-grandchildren with larger brains.
- jjk166 6y agoIt doesn't cause the genetic change, the genetic change is random. But if you were, simply by chance, born with a bigger brain that required more calories to support, you would be at a disadvantage to everyone else, and your mutation would quickly die out unless you were in a situation where you had excess calories available, such as by eating meat.
- yellowapple 6y agoIt doesn't seem that nonsensical to me when considering things like epigenetics. It also doesn't seem all that nonsensical if you flip the causality to "some genetic change resulted in more brain activity/growth and necessitated more protein consumption as a result".
- marshray 6y agoRight, phrasing it as "meat causes brains" confuses the direction of causality and fails to explain all the meat-eating animals that didn't grow large brains.
- Maursault 6y ago> As protohumans and humans invaded lands, they likely extincted megafauna... It is not as certain as most non-experts believe and a controversial subject among experts why megafauna seems to have died out globally rather quickly. So to use "likely" is too strong. "Possibly," is a far better descriptor here: did a global human population of only 1M-15M at the end of the last ice age really kill all of the megafauna everywhere, at once? Humans possibly contributed, but with only sticks and stones technology, how could so few kill every last one of what must have been enormous populations of megafauna? And why?
- JumpCrisscross 6y ago> You don't chase down most little critters, you bait and trap The switch, from large to small, seems critical. Hunting big game requires cooperation and communication. That tooling gets supercharged when it has to domain switch. (Counterfactual: forcing lions to sustain themselves on rabbits will probably produce prides of dead lions.)
- sitkack 6y agohttps://en.wikipedia.org/wiki/Protein_poisoning https://en.wikipedia.org/wiki/Protein_poisoning
- jbotz 6y agoI just watched "Kingdom of the White Wolf" on Disney+ which has exactly that situation. The white wolves of Ellesmere island hunt musk oxen; there isn't much else there except snow hares. At one point after not managing to take down a musk ox for a while they do hunt the snow hares and manage to get one... which serves to cement their pack bonds, but the calories gained were probably less than what the spent on that hunt. Great mini-series, recommended.
- jvanderbot 6y agoI believe that the series of extinctions that cleared the way for (and perhaps necessitated) the rise of intelligence in apes was the great filter. I can't ignore global warming as another possible filter, but I think the big one is behind us.
- darkmarmot 6y agoI fear the collapse that will accompany the Holocene Extinction is unfortunately ahead of us.
- testfoobar 6y agoAnd is happening at a rate that is hard to fathom...
- BiteCode_dev 6y agoAssuming there is only one big filter, which I think is unlikely. Any mega black swan event is a filter in its own since it's disturbing the system you are adapted to. The worse event is one that disturbs the system you are dependant on. Climat change is terrible, but it could be worse. We depend on oxygen. Gravity. What else await for us ?
- jvanderbot 6y agoIf you define a great filter as something that statistically prevents the preponderance of life in the galaxy, then "any mega black swan even" is just noise. With small likelihood, it will wipe out a civilization, (definition of black swan). But for it to be a great filter per definition, it has to somewhat reliably affect all potentially universe-spanning intelligence. All I'm saying is that most likely, once an intelligent tribe of creates arises, it's likely to go on to dominate the planet, and likely to go on to reach technological readiness to go to space (assuming it can get access to energy easily, which may be another small filter). So, you're not wrong, all dangers events could be humanity's end, I'm just saying something more general -- that civilization-limiting events are probably clustered before the civilization arises.
- sgt101 6y agoOk - so how does this account for the hunter gatherer cultures in North America and Africa into modern times? Bison do not count as small game. Also, if you kill an elephant how much of that beast can you (and all your tribe) hope to eat? I'm not even sure if this is a causal inversion or just a co-incidence; humans may well have had nothing to do with big game until they were anatomically modern. Where is the evidence that Little Foot and Lucy killed anything bigger than a mouse?
- Schmools 6y agoThere's actually some evidence (though also some debate) that early human hunting led to the extinction of megafauna in North America in the late Pleistocene age. https://science.sciencemag.org/content/306/5693/70.full https://science.sciencemag.org/content/306/5693/70.full
- sgt101 6y agoBut these were anatomically modern people - the North American Megafauna were around 50k years ago... There is no evolutionary pressure there!
- Schmools 6y agoYeah, I realized that as soon as I posted, an interesting paper nonetheless. I thought I had also read a paper discussing protohuman hunting practices earlier in the year but I couldn't find it here. Certainly anatomically modern early humans had much more of an impact on our environment then we often give them credit for.
- Schmools 6y agoInterestingly in the intro to "Animals in Translation" Temple Grandin discusses the fact that is highly possible that in fact human brain size decreased with the domestication of animals (she discusses dogs specifically who she also posits we may have helped us develop social relationships with eachother).
- codesnik 6y agoI sometimes joke that our brains were needed during glacial periods to survive, and now we just invent chores and make fuss over everything just to keep it busy.
- bluefirebrand 6y agoWhere's the joke though?
- EGreg 6y agoAs people needed to understand jokes and attract mates, their brains grew to make that happen. - Lamarck
- bigpumpkin 6y agoAlternatively, humans hunted the big games to death after acquiring big brains that enabled more cooperation when hunting. Curious if the decline in big game happened in places without humans.
- jessaustin 6y agoThe last mammoths lived on an island without humans. Or perhaps, without humans until the very moment that those particular mammoths died out. https://www.sciencedaily.com/releases/2019/10/191007081750.htm https://www.sciencedaily.com/releases/2019/10/191007081750.h...
- karpierz 6y agoThis line of thinking falls into a common issue I have with evo-psych work. The paper proposes a mechanism that could select for intelligence, but doesn't provide evidence that the mechanism caused humans to evolve to be intelligent. It's the equivalent of the "Is-Ought" fallacy for empirical sciences.
- otabdeveloper4 6y agoA charitable way to put it. The more straightforward term is "just-so story".
- Hermel 6y agoWould a mechanism that selects for more intelligence automatically create evolutionary pressure into that direction?
- AnimalMuppet 6y agoIf that proposed mechanism is actually operating in practice, and if there are no other mechanisms that counteract it, then yes, it would.
- raincom 6y agoIt is called ad hoc explanation.
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- progre 6y agoKinda weird to bring the Neanderthals into it in the last quote. First, the timeline don't quite fit, there seems to still have been large prey around when the Neanderthals disappeared. Second, I thought the modern view was that they merged back in to the homo sapiens line rather than outright die off?
- astrange 6y agoSome of them did, but recent evidence is showing that European Neanderthals were older than we thought they were, which reduces the interbreeding a bit. https://phys.org/news/2021-03-neanderthals-europe-earlier-thought.html https://phys.org/news/2021-03-neanderthals-europe-earlier-th...
- rickspencer3 6y agoThe assertion that humans are unable to stop themselves from completely depleting the resources that they depend on rings true to me. I think Jared Diamond wrote a whole book about this.
- jjk166 6y agoCan you name a single culture that knowingly overexploited a resource they could not live without until they died out? There have certainly been cases of overexploitation leading to the extinction of species that people didn't need to survive, as well as potential cases where human activity may have led to ecological collapse by mechanisms the people did not understand, but I honestly can't think of a single instance where a substantial population depleted a resource it knew it needed to survive. On the other hand, I can think of many cultures that lasted for many thousands of years in geographies with limited resources like islands.
- fnord77 6y agoso with the mass extinction of the honey bee, we'll turn into super geniuses and convert nuclear fusion directly into food.
- xaedes 6y ago"convert nuclear fusion directly into food" You mean like plants, fruits and vegetables do?
- fnord77 6y agodisintermediation
- delecti 6y agoThe supply chain would have a few steps between fusion and food, but if we had fusion powered electricity generation then the end result isn't too far removed from that. Fusion > electricity > hydrogen via hydrolysis > Haber process produced fertilizer > food
- deleted 6y ago[deleted]
- imbnwa 6y agoThe Khoisan people are the oldest living lineage of humans IIRC and they only adopted agriculture in the last century.
- ArkanExplorer 6y ago"As they adapted to hunting... brain volume [grew] from 650cc to 1,500cc." "As humans moved into permanent settlements and became farmers, their brain size decreased to its current volume of 1300-1400cc." Its interesting that we today have smaller brains than our prehistoric ancestors. I wonder if we can look through our genetic code and find some remnants of this past, and re-engineer the relevant genes into future generations? https://www.sciencedirect.com/science/article/abs/pii/S016028960200137X https://www.sciencedirect.com/science/article/abs/pii/S01602... Given that Asians (1364cc) have a larger brain size than Whites (1347cc) and Blacks (1267cc), did these kind of pre-historic trends also play out differently across different landmasses?
- aritmo 6y agoDo we really currently use our brains as efficiently as possible? The decrease in size could be the outcome of one of the bottlenecks, like the one 200k years ago.
- ArkanExplorer 6y agoThe problem could be with distribution. In a hunter-gatherer society, all members require this intelligence described in the article. In a hierarchical early agricultural society, only the ruling classes and to an extent middle classes do. Thus you end up with a distribution of intelligence (and brain size) aligned along caste, with a wide range. Who you sample influences your measurements.
- vkou 6y agoWhy do you assume that being a subsistence farmer requires less intelligence than being a landlord? Peasants were poor, not stupid. [1] Their landlords may have written about them as if they were, but they were hardly unbiased observers. [1] https://acoup.blog/2020/07/24/collections-bread-how-did-they-make-it-part-i-farmers/ https://acoup.blog/2020/07/24/collections-bread-how-did-they...
- deleted 6y ago[deleted]
- forgotmypw17 6y agothe sexual selection theory presented in the book ,,the mating mind,, is the most plausible i,ve read to date, including compared to this one.
- EGreg 6y agoAs these “just so” stories explain how something grew or developed over multiple generations, we should keep in mind something that isn’t stated: for this to happen, tons of humans were apparently dying of hunger, unable to get enough to eat, before they passed on their genes. Either that or the humans with larger brains were able to survive better and have more children for other reasons. But then the reductionist theory is wrong. Hmm which is more likely?
- hirundo 6y agoIf effective predation begets sentience, there may be a tendency for sentient life forms to derive from effective predators. Public service announcement: Exercise caution during close encounters with space aliens.
- choxi 6y ago> In recent years more and more evidence has been accumulated to the effect that humans were a major factor in the extinction of large animals What about this? https://www.nature.com/articles/s41467-021-21201-8 https://www.nature.com/articles/s41467-021-21201-8 I think "climate change" is potentially an important confounding variable here. Also I thought "animals" would link to a source but it just searches their site for the word "animals".
- frongpik 6y agoImo, most of the evolution science of today is about inventing a cool story to justify the very little data we have. We have what, a bit over ten thousand years of definitive history with solid data, and based on this tiny slice of history we invent grandiose theories of where the man's intelligence came from.
- mooneater 6y ago> enabled more efficient hunting of medium-sized and small animals—until these populations also dwindled This means humans have been decimating wild animal populations for a very long time, we are accustomed to it. But we need to stop it now.
- JoeAltmaier 6y agoNo problem! There are hardly any wild animals now. Their body mass represents 4% of the world total animal body mass. Humans are 25%, and our farmed animals the rest.
- _RPL5_ 6y agoI find their hypothesis suspect. > According to the researchers, the decrease in the size of game and the need to hunt small, swift animals forced humans to display cunning and boldness—an evolutionary process that demanded increased volume of the human brain. There are plenty of predators that hunt fast small prey, but don't have advanced cognitive capacities. Cats, for example, are adapted to hunting rodents, but have pretty small brains. > As humans moved into permanent settlements and became farmers, their brain size decreased to its current volume of 1300-1400cc. This happened because, with domesticated plants and animals that don't take flight, there was no more need for the allocation of outstanding cognitive abilities to the task of hunting. There are active hunter-gatherer societies out there (or at least societies that lean heavily that way along the hunter-farmer axis). Do these societies have larger brains than everyone else? Seems like a simple way to test their hypothesis.
- jiofih 6y agoI’m sorry but this is very low effort commentary. Is it adding anything new to discussion? Seems pointless to dispute the paper’s hypothesis with a handful of anecdotes.
- iujjkfjdkkdkf 6y agoI think some cats are different because they are antisocial and there aren't that many of them. Compared to humans (and e.g. dogs) that have to hunt but also feed a group and support a social structure. Social cats like lions I believe do mostly eat bigger game. But cats overall are also extremely smart compared to most animals. Look into how intelligent tigers are. But they dont collaborate so they don't need that side of intelligence. I do like your idea about the extant hunter gatherers, that should be easy to confirm.
- tshaddox 6y ago> There are plenty of predators that hunt fast small prey, but don't have advanced cognitive capacities. The hypothesis doesn’t imply that large brains are necessary for any animal to hunt small fast prey. Cats are really fast and have great senses and built-in weapons and it was probably “easier for evolution” to improve the brain than to build cat-like senses and weapons from scratch.
- sebmellen 6y agoI much prefer the stoned ape theory https://youtube.com/watch?v=Nxn2LlBJDl0 https://youtube.com/watch?v=Nxn2LlBJDl0
- vmception 6y agoI'm not really convinced by the accepted logic that if you put more neurons in a room that they eventually start questioning the universe.
- lurquer 6y agoI’m not entirely convinced with their underlying assumption about big vs small animals... It should be tested. The authors of the study should try to catch a bear. And then try to catch a mouse. See if there is a correlation to their IQs.
- doggodaddo78 6y agoThe first chapter of Diamond's Guns, Germs, & Steel takes a crack at this.
- sitkack 6y agoThe large brains need more fat (calories), which allow them to hunt more effectively and take larger game (more calories). Large animals just happen to be in the wrong place at the wrong time.
- BerislavLopac 6y agoI am convinced that a lot of human traits could be explained if, at a critical point in our evolutional history, our ancestors spend a lot of time wading in shallow water -- not unlike those Japanese macaques who keep warm at winter by dipping in hot springs. [0] Bipedalism, body hair patterns subcutaneous fat, large brain (and, very much related to it, difficult birth), even language -- all these features make a lot of sense if you spend a lot of time in the water, leaving it occasionally to forage. Unfortunately, I am aware of very little research in that direction, and many attempts have been shot down because of the bad reputation of the original "aquatic ape hypothesis" [1]. [0] https://www.nationalgeographic.com/animals/article/japanese-snow-monkey-macaques-bath-stress-spd https://www.nationalgeographic.com/animals/article/japanese-... [1] https://en.wikipedia.org/wiki/Aquatic_ape_hypothesis https://en.wikipedia.org/wiki/Aquatic_ape_hypothesis
- matznerd 6y agoYou are on the target. Fish contain high levels of the fatty acid DHA. DHA is the main limiting factor on the growth of the brain, and needed exogenously (AA needed too, but can be converted internally). Humans cannot easily get access to DHA from things like grass. That’s why large herbivores grow in bodymass, but their brain size (encephalizatiom quotient) stays low. Dolphins, who eat primarily fish, have a much more similar brain to us, and one of the highest encephalization quotients... Due to changes in geography in Africa, proto-humans found themselves along the shorelines with ample supples of fish for the first time. They ate more DHA, which lead to the growth in brain cells (brains are built of these fatty acids). This extra brain power, through the process known as exaptation (the lesser known evolutionary concept to survival of the fittest), is what is theorized to have then opened the door the human creativity, symbols, language, etc. Basically, our bigger brains were caused by an increase in the previously limiting nutrient, which was then put to to use for advanced traits, not the other way around as this article purports.... That is a TL;DR as don’t have time to write it all out, but have written and presented on this topic... https://www.wiley.com/en-us/Human+Brain+Evolution%3A+The+Influence+of+Freshwater+and+Marine+Food+Resources-p-9780470452684 https://www.wiley.com/en-us/Human+Brain+Evolution%3A+The+Inf... Edit: this abstract below has a good summary, and book above is great compilation of papers on the topic. “The circumstances of human brain evolution are of central importance to accounting for human origins, yet are still poorly understood. Human evolution is usually portrayed as having occurred in a hot, dry climate in East Africa where the earliest human ancestors became bipedal and evolved tool-making skills and language while struggling to survive in a wooded or savannah environment. At least three points need to be recognised when constructing concepts of human brain evolution : (1) The human brain cannot develop normally without a reliable supply of several nutrients, notably docosahexaenoic acid, iodine and iron. (2) At term, the human fetus has about 13 % of body weight as fat, a key form of energy insurance supporting brain development that is not found in other primates. (3) The genome of humans and chimpanzees is <1 % different, so if they both evolved in essentially the same habitat, how did the human brain become so much larger, and how was its present-day nutritional vulnerability circumvented during 5-6 million years of hominid evolution ? The abundant presence of fish bones and shellfish remains in many African hominid fossil sites dating to 2 million years ago implies human ancestors commonly inhabited the shores, but this point is usually overlooked in conceptualizing how the human brain evolved. Shellfish, fish and shore-based animals and plants are the richest dietary sources of the key nutrients needed by the brain. Whether on the shores of lakes, marshes, rivers or the sea, the consumption of most shore-based foods requires no specialized skills or tools. The presence of key brain nutrients and a rich energy supply in shore-based foods would have provided the essential metabolic and nutritional support needed to gradually expand the hominid brain. Abundant availability of these foods also provided the time needed to develop and refine proto-human attributes that subsequently formed the basis of language, culture, tool making and hunting. The presence of body fat in human babies appears to be the product of a long period of sedentary, shore-based existence by the line of hominids destined to become humans, and became the unique solution to insuring a back-up fuel supply for the expanding hominid brain. Hence, survival of the fattest (babies) was the key to human brain evolution.” https://pubmed.ncbi.nlm.nih.gov/16828044/ https://pubmed.ncbi.nlm.nih.gov/16828044/
- robwwilliams 6y agoA “just-so” story; not science. So many factors could have and probably did contribute to CNS enlargement. But no way for this article to be more than a plausible speculation. Most work on “human exceptionalism” falls into the just-so story category. Not actually pseudo-science, but para-science that cannot be tested or deconfounded.
- HarHarVeryFunny 6y agoOur large brains are good for prediction and problem solving in complex environments... capabilities needed to be a generalist rather than a specialist. Changing food sources may be part of the picture, but it seems more likely that it'd be a need to utilize more varied and unpredictable food sources, not just a different staple, that'd require these capabilities. It also seems inevitable that there'd have been multiple selection pressures all acting on whatever evolving capabilities we had. Maybe changing food sources upset the status quo, and favored some initial spurt in brain growth, but that in turn would eventually have lead to new social/communication capabilities (and what else?) that would have themselves then acted as differentiators for selection. The story of the selection pressures acting along our evolutionary history is going to be multifacted and messy, ergo any simple explanation is at best incomplete or wrong. Why didn't all animals preying on these larger animals develop large brains? Where are the sabre-tooth developers among us?
- ajuc 6y agoIntelligence is meta-adaptation - adaptation that allows you to adapt to environment changes on the fly (without wasting many generations for mutation and selection). So, the evolutionary pressure must have been something that required adaptation within one generation - for hundreds of generations. If the need for adaptation was a single big event - brains wouldn't have the time to evolve - it would be easier to adapt directly. You don't need human-level intelligence to hunt big prey nor small prey. The changes must have been frequent enough to be worth wasting calories on bigger and bigger brains and supporting them through the time when there were no changes to adapt to. So I don't think overhunting was it. Every predator species deals with overhunting.
- excalibur 6y ago> "Wherever humans appeared—whether homo erectus or homo sapiens, we see, sooner or later, mass extinction of large animals... But while other species, like our cousins the Neanderthals, became extinct when their large prey disappeared, homo sapiens decided to start over again, this time relying on agriculture." Now homo erectus is apparently included as a variety of human, and Neanderthals are still relegated to "cousins".
- aitchnyu 6y agoI read an old book saying human brain evolved timing circuits to throw projectiles and it contributed to areas like sports, music, performance arts and culture. How does this hypothesis hold?