The human brain grew as a result of the extinction of large animals: new paper(phys.org)
phys.org
The human brain grew as a result of the extinction of large animals: new paper
https://phys.org/news/2021-03-human-brain-grew-result-extinction.html
103 comments
> 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.
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.
I’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.
I 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.
I do like your idea about the extant hunter gatherers, that should be easy to confirm.
This 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.
It's the equivalent of the "Is-Ought" fallacy for empirical sciences.
A charitable way to put it. The more straightforward term is "just-so story".
Thanks for pointing me to that term, I've been looking for a more succinct description for this.
It's not just a term it's also a book!
https://en.wikipedia.org/wiki/Just_So_Stories
https://en.wikipedia.org/wiki/Just_So_Stories
How about the opposite. Smart humans could hunt dangerous animals. The causality is not obvoius ...
This was my first thought as well.
This is more or less what Yuval Noah Harari lays out in the first section of his book 'Sapiens': 1 - homo sapiens have a cognitive revolution 70k years ago which makes them able to think and communicate in more sophisticated ways. 2 - homo sapiens spread all around the world and wipe out ~all the large animals (including other human species..). His evidence from various places (Australia, America, various islands) of humans arriving then the large animals disappearing is pretty convincing.
Interestingly, this isn't "evo-psych work", as anyone would see who'd knew how evolutionary psychology works.
In fact, the kind of argument used by the authors is more in line what human paleontology looks like.
In fact, the kind of argument used by the authors is more in line what human paleontology looks like.
I wonder what caused dolphins to evolve their intelligence. I don't think they hunted underwater mammoths :)
I mean, could they have? "Mammoths" in this case could be whales, sharks, and other large aquatic creatures. Considering the relative lack of deep sea archaeology going on, there could be an abundance of evidence of this that we simply haven't noticed. Plus, there's even extant examples of dolphins hunting sharks (and even knowing to flip them over to render them helpless).
It is called ad hoc explanation.
Thanks, I didn't know about this: https://en.wikipedia.org/wiki/Ad_hoc_hypothesis
Would a mechanism that selects for more intelligence automatically create evolutionary pressure into that direction?
If that proposed mechanism is actually operating in practice, and if there are no other mechanisms that counteract it, then yes, it would.
I often find it "justifying human exceptionalism" presented as science. The unstated assumption is that humans are somehow better than chimpanzees (here, it is almost literally stated), and therefore that we must reverse engineer and fill in the gaps to justify this. It strikes me that I have no reason to believe the assumption, nor any way of reverse engineering the random process of natural selection.
In my opinion, other sciences are not immune to this.
In my opinion, other sciences are not immune to this.
> The unstated assumption is that humans are somehow better than chimpanzees
"Better" always has to carry the "at what?" part, explicitly or implicitly. There's no universal Better, thus humans aren't Better than chimpanzees - but humans are better than chimpanzees at quite a lot of things, including intelligence, learning, preserving knowledge across generations, use of tools...
> therefore that we must reverse engineer and fill in the gaps to justify this
There's nothing to justify here. We just are better - by far - than every other animal on this planet at the things that makes a species rule every other. This is an observable fact of reality. We had no contenders for this status as far as the recorded history goes. But it's interesting why this is the case. Why us, and not chimpanzees.
> any way of reverse engineering the random process of natural selection
Natural selection isn't completely random! If it were, there wouldn't be any complex life forms on Earth. Or, more strictly, for natural selection to be completely random, the universe would have to be a fully uniform blob of matter.
There's randomness involved in natural selection, but that randomness has a strong bias. That bias itself is the part that's interesting to understand / reverse engineer.
"Better" always has to carry the "at what?" part, explicitly or implicitly. There's no universal Better, thus humans aren't Better than chimpanzees - but humans are better than chimpanzees at quite a lot of things, including intelligence, learning, preserving knowledge across generations, use of tools...
> therefore that we must reverse engineer and fill in the gaps to justify this
There's nothing to justify here. We just are better - by far - than every other animal on this planet at the things that makes a species rule every other. This is an observable fact of reality. We had no contenders for this status as far as the recorded history goes. But it's interesting why this is the case. Why us, and not chimpanzees.
> any way of reverse engineering the random process of natural selection
Natural selection isn't completely random! If it were, there wouldn't be any complex life forms on Earth. Or, more strictly, for natural selection to be completely random, the universe would have to be a fully uniform blob of matter.
There's randomness involved in natural selection, but that randomness has a strong bias. That bias itself is the part that's interesting to understand / reverse engineer.
I appreciate these points, which are well-considered.
> But it's interesting why this is the case. Why us, and not chimpanzees.
As you admit, we could ask about exceptional adaptations in other species, e.g. "why do birds rule the sky, and not other species?". This might be sometimes studied, but there is not nearly a comparable level of interest in that form of exceptionalism. I'd say there's so little interest, that we often fail to even observe such cases.
It strikes me that we are really just interested in ourselves. (I have no problem with that.)
I don't think we will learn very much as long as we start with the assumption we are primarily exceptional above all other species. I think it immediately leads to circular logic, where any and all differences become evidence supporting the assumption.
I accept what you say about natural selection having a bias. I remain doubtful that we are truthfully observing that bias over the noise of essential randomness. (Edit: on further consideration, I'd strengthen this and believe it is statistically impossible to distinguish evolutionary pressure from randomness, if you are considering N=1 runs of evolution).
> But it's interesting why this is the case. Why us, and not chimpanzees.
As you admit, we could ask about exceptional adaptations in other species, e.g. "why do birds rule the sky, and not other species?". This might be sometimes studied, but there is not nearly a comparable level of interest in that form of exceptionalism. I'd say there's so little interest, that we often fail to even observe such cases.
It strikes me that we are really just interested in ourselves. (I have no problem with that.)
I don't think we will learn very much as long as we start with the assumption we are primarily exceptional above all other species. I think it immediately leads to circular logic, where any and all differences become evidence supporting the assumption.
I accept what you say about natural selection having a bias. I remain doubtful that we are truthfully observing that bias over the noise of essential randomness. (Edit: on further consideration, I'd strengthen this and believe it is statistically impossible to distinguish evolutionary pressure from randomness, if you are considering N=1 runs of evolution).
Evo-psych is certainly concerned with the psychology of other animals - why for example the peacock has its feathers. But we can't have a peacock say "I don't know, the feathers don't seem sexy to me, but if I were a tiger I think I'd be scared of them."
Humans have both much more complicated psychologies than most animals (whether we have true peers is debatable), and we certainly are much easier to collect data on. It makes sense that human evo-psych should dwarf animal evo-psych for the same reasons terrestrial-biology dwarfs astro-biology. I wouldn't interpret that to mean we don't consider the questions interesting.
Humans have both much more complicated psychologies than most animals (whether we have true peers is debatable), and we certainly are much easier to collect data on. It makes sense that human evo-psych should dwarf animal evo-psych for the same reasons terrestrial-biology dwarfs astro-biology. I wouldn't interpret that to mean we don't consider the questions interesting.
Mutation is completely random and selection mostly isn't. Many confuse mutation with selection.
Yeah.
We are just primates, doing what all primates do just with a lot more suave and panache
Not much more really.
We are just primates, doing what all primates do just with a lot more suave and panache
Not much more really.
>I often find it "justifying human exceptionalism" presented as science. The unstated assumption is that humans are somehow better than chimpanzee
You find it unscientific to observe that humans are exceptional for being the only known species with the ability to dominate and shape any environment, create, process, and communicate abstract thought, practice science, generate art, communicate across the planet instantly, travel to the bottom of the ocean and to space, with technology that other humans conceived of, designed, and built?
If that isn't scientifically provable exceptionalism, I don't know what is. "Better" is a loaded term because you can weasel in talk of destroying the environment and what not - but I don't think there's any argument against obvious and overwhelming human exceptionalism, the origin of which unquestionably begs exploration and explanation.
You find it unscientific to observe that humans are exceptional for being the only known species with the ability to dominate and shape any environment, create, process, and communicate abstract thought, practice science, generate art, communicate across the planet instantly, travel to the bottom of the ocean and to space, with technology that other humans conceived of, designed, and built?
If that isn't scientifically provable exceptionalism, I don't know what is. "Better" is a loaded term because you can weasel in talk of destroying the environment and what not - but I don't think there's any argument against obvious and overwhelming human exceptionalism, the origin of which unquestionably begs exploration and explanation.
> If that isn't scientifically provable exceptionalism, I don't know what is
My point is that it isn't scientific at all.
Any person can declare themselves exceptional - I have observed consistently that if a person has to declare they are exceptional themselves, it means they probably aren't.
I don't assume that general rule to be different on a species-level: if we (as the human race) feel a need to spend a lot of effort making claims to why we are exceptional, acting both as the judge and the jury, it leads me to suspect that we probably are not.
My point is that it isn't scientific at all.
Any person can declare themselves exceptional - I have observed consistently that if a person has to declare they are exceptional themselves, it means they probably aren't.
I don't assume that general rule to be different on a species-level: if we (as the human race) feel a need to spend a lot of effort making claims to why we are exceptional, acting both as the judge and the jury, it leads me to suspect that we probably are not.
The immediate consequence of me reading evo-psych work, is that I conclude that pretty much all evo-psych work should be piled into a large bonfire, and burned.
This is the direct result of an obvious evolutionary psychological adaptation - being warm helps people survive, and fire is warm - therefore, if I were to do that, I would just be following an, ahem, evolutionary imperative.
This is the direct result of an obvious evolutionary psychological adaptation - being warm helps people survive, and fire is warm - therefore, if I were to do that, I would just be following an, ahem, evolutionary imperative.
I agree with your criticism.
Still, I'm trying to figure out exactly what my issue is with evo-psych claims that I don't have with e.g. physics claims.
There seem to be some commonalities between the two fields: developing models to explain empirical data. And when working with their models, they're willing to assume a certain degree of causality.
I wonder if my issue is that evo-psych is a lot more like history than like physics, in that it's really hard to do repeatable experiments to vet their theories? So when we hear an evo-psych theory stated with confidence, it discredits the speaker?
Still, I'm trying to figure out exactly what my issue is with evo-psych claims that I don't have with e.g. physics claims.
There seem to be some commonalities between the two fields: developing models to explain empirical data. And when working with their models, they're willing to assume a certain degree of causality.
I wonder if my issue is that evo-psych is a lot more like history than like physics, in that it's really hard to do repeatable experiments to vet their theories? So when we hear an evo-psych theory stated with confidence, it discredits the speaker?
> Still, I'm trying to figure out exactly what my issue is with evo-psych claims that I don't have with e.g. physics claims.
Can you give an example of an analogous claim in physics that you have an easier time accepting?
Not flaming. Just trying to understand a similar situation that might arise from physics.
One of the main issues I have with evo-psych is that you can't run rigorous control experiments, so my "analysis" of the claims amounts to "Well, that seems like a reasonable explanation. But so do a hundred other models...."
Can you give an example of an analogous claim in physics that you have an easier time accepting?
Not flaming. Just trying to understand a similar situation that might arise from physics.
One of the main issues I have with evo-psych is that you can't run rigorous control experiments, so my "analysis" of the claims amounts to "Well, that seems like a reasonable explanation. But so do a hundred other models...."
Again, I'm just trying to understand why my BS detector squeals at evo-psych and not physics.
Regarding an example: I was thinking along the lines of physics models that, in daily use, physicists treat as genuinely true. This includes concepts that are somewhat problematic, like true causality. (E.g., Newtonian mechanics as taught in high-school.)
But after some more thought, I think my real issue is how the two communities vet their theories. My simplistic take on it is:
The physics community has a healthy focus on refutability. IIUC, the community has little tolerance for someone even posing an unrefutable theory, let alone espouse it as likely truth.
The evo-psych community (and I could be mistaken) is much more tolerant of people advancing theories that are (practically speaking) untestable as though they were genuinely true.
Regarding an example: I was thinking along the lines of physics models that, in daily use, physicists treat as genuinely true. This includes concepts that are somewhat problematic, like true causality. (E.g., Newtonian mechanics as taught in high-school.)
But after some more thought, I think my real issue is how the two communities vet their theories. My simplistic take on it is:
The physics community has a healthy focus on refutability. IIUC, the community has little tolerance for someone even posing an unrefutable theory, let alone espouse it as likely truth.
The evo-psych community (and I could be mistaken) is much more tolerant of people advancing theories that are (practically speaking) untestable as though they were genuinely true.
I 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.
Where's the joke though?
As people needed to understand jokes and attract mates, their brains grew to make that happen. - Lamarck
I 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-...
[1] https://en.wikipedia.org/wiki/Aquatic_ape_hypothesis
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-...
[1] https://en.wikipedia.org/wiki/Aquatic_ape_hypothesis
You 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+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/
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+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/
I think all the brain matter can be composed by the body itself, indcluding DHA or DHEA. It is just easier to get big quantities from exogenous sources. The world champion of chess, Carlsen, comes from Norway where they produce the most salmon in the world. You can buy salmon everywhere, relatively cheap comparing to other places.
However i am a vegan for 4 years, and i think my brain never worked better. Everything that comes from animal sources, can be substituted by plants, or from endogenous production of the body.
How about our brain got evolved because of our vocal chords? I didn't see anyone considering that hypothesis. I can personally can imitate many animals, birds or whatever. My ancestors, ancient Greeks said that music is the ultimate art. How about we are making music for millions of years, and our brain processing that information, got so much ahead of all the other organisms?
However i am a vegan for 4 years, and i think my brain never worked better. Everything that comes from animal sources, can be substituted by plants, or from endogenous production of the body.
How about our brain got evolved because of our vocal chords? I didn't see anyone considering that hypothesis. I can personally can imitate many animals, birds or whatever. My ancestors, ancient Greeks said that music is the ultimate art. How about we are making music for millions of years, and our brain processing that information, got so much ahead of all the other organisms?
We can endogenously produce it by converting it from ALA, but that conversion is very inefficient (5 percent), it doesn't result in the most bioavailable form (lyso-DHA) and most sources of ALA have high omega-6s.
Not to mention there's going to be significant individual variability regarding the capability of converting ALA. Likely, some are going to do a great job of it, and others not so much. Just look at how much heterogeneity there is in the endogenous production of gut myrosinaise for example.
Our bodies were designed to consume some fish, even if we can do without.
Not to mention there's going to be significant individual variability regarding the capability of converting ALA. Likely, some are going to do a great job of it, and others not so much. Just look at how much heterogeneity there is in the endogenous production of gut myrosinaise for example.
Our bodies were designed to consume some fish, even if we can do without.
Fantastic. Here is your Nobel prize for this discovery:
Our 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?
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?
Imo, 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.
You don't chase down most little critters, you bait and trap. That does require being less of a dummy.
Interesting. 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.
As 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.
> 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?
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?
It'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.
It seems nonsensical to me that simply eating meat protein could somehow cause a genetic change leading to great-grandchildren with larger brains.
It 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.
It 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".
Right, 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.
Not directly related, but I find myself to be mentally sharper when hungry, if on edge a little.
> 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.)
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.)
I 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.
Great mini-series, recommended.
Intelligence 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.
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.
If 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.
I 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.
I can't ignore global warming as another possible filter, but I think the big one is behind us.
Assuming 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 ?
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 ?
If 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.
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.
It may very well be after it ,still due to “black swan” type events. With technology continuing to progress, there may be a point where a small group of dedicated people can construct enough nuclear warheads for a nuclear winter, or engineer the perfect deadly virus with a large incubation period. And/or if we develops AGI, that a single malicious group controlling an AGI can end all life on earth. Technology will continue to advance, and it is easier to destroy than to create.
https://en.wikipedia.org/wiki/Global_catastrophic_risk
https://en.wikipedia.org/wiki/Global_catastrophic_risk
This is, at the very least, an interesting though experiment.
We often suppose:
We often suppose:
(we can't find intelligent extraterrestrials)⊃(there is a great filter ahead of us)
(we have passed a great filter)⊃(there aren't many intelligent extraterrestrials)
I fear the collapse that will accompany the Holocene Extinction is unfortunately ahead of us.
And is happening at a rate that is hard to fathom...
A “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.
Interestingly 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).
As 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?
Kinda 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?
Some 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-th...
https://phys.org/news/2021-03-neanderthals-europe-earlier-th...
Alternatively, 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.
The 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.h...
https://www.sciencedaily.com/releases/2019/10/191007081750.h...
> 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
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".
What about this? 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".
I much prefer the stoned ape theory https://youtube.com/watch?v=Nxn2LlBJDl0
> "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".
Now homo erectus is apparently included as a variety of human, and Neanderthals are still relegated to "cousins".
I'm not really convinced by the accepted logic that if you put more neurons in a room that they eventually start questioning the universe.
The Khoisan people are the oldest living lineage of humans IIRC and they only adopted agriculture in the last century.
I’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.
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.
I 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?
The 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.
so with the mass extinction of the honey bee, we'll turn into super geniuses and convert nuclear fusion directly into food.
The 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
Fusion > electricity > hydrogen via hydrolysis > Haber process produced fertilizer > food
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The first chapter of Diamond's Guns, Germs, & Steel takes a crack at this.
> 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.
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.
No 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.
the sexual selection theory presented in the book ,,the mating mind,, is the most plausible i,ve read to date, including compared to this one.
The 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.
Can 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.
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.
Ok - 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?
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?
There'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
But these were anatomically modern people - the North American Megafauna were around 50k years ago... There is no evolutionary pressure there!
Yeah, 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.
"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/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?
"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/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?
Another thing to be cautious of is that brain volume is only a proxy for e.g. neuron count, which is itself a proxy for intelligence.
Volume may be the only archaeological data available, but whales (8kg) and elephants (5kg) have brains many times larger than ours (~1.3kg), and even adjusting for body mass doesn’t make humans top of the pile — famously, the brain-to-body mass ratio of shrews is higher than humans’.
Volume may be the only archaeological data available, but whales (8kg) and elephants (5kg) have brains many times larger than ours (~1.3kg), and even adjusting for body mass doesn’t make humans top of the pile — famously, the brain-to-body mass ratio of shrews is higher than humans’.
Might want to check your facts. Especially since you're citing this person: https://en.wikipedia.org/wiki/J._Philippe_Rushton
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Do 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.
The decrease in size could be the outcome of one of the bottlenecks, like the one 200k years ago.
The 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.
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.
Why 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...
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...
Is there a particular reason that you cite a 20-year old, paywalled study that claims black people are genetically stupider than other races here?
Polynesians have the most average CCs of brain. There's no correlation between this and smart.
> 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.