[HN Gopher] The human brain grew as a result of the extinction o...
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The human brain grew as a result of the extinction of large
animals: new paper
Author : Hooke
Score : 64 points
Date : 2021-03-16 00:11 UTC (1 days ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| lurquer wrote:
| 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.
| sitkack wrote:
| 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.
| sgt101 wrote:
| 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?
| Schmools wrote:
| 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
| fnord77 wrote:
| so with the mass extinction of the honey bee, we'll turn into
| super geniuses and convert nuclear fusion directly into food.
| delecti wrote:
| 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
| [deleted]
| imbnwa wrote:
| The Khoisan people are the oldest living lineage of humans IIRC
| and they only adopted agriculture in the last century.
| airhead969 wrote:
| You don't chase down most little critters, you bait and trap.
| That does require being less of a dummy.
| JumpCrisscross wrote:
| > _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 wrote:
| https://en.wikipedia.org/wiki/Protein_poisoning
| jbotz wrote:
| 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.
| tashoecraft wrote:
| 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.
| airhead969 wrote:
| 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.
| tashoecraft wrote:
| 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.
| marshray wrote:
| It seems nonsensical to me that simply eating meat
| protein could somehow cause a genetic change leading to
| great-grandchildren with larger brains.
| jjk166 wrote:
| 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.
| bazooka_penguin wrote:
| Not directly related, but I find myself to be mentally
| sharper when hungry, if on edge a little.
| Schmools wrote:
| 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).
| _RPL5_ wrote:
| I 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.
| iujjkfjdkkdkf wrote:
| 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.
| codesnik wrote:
| 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.
| bluefirebrand wrote:
| Where's the joke though?
| EGreg wrote:
| As people needed to understand jokes and attract mates, their
| brains grew to make that happen. - Lamarck
| bigpumpkin wrote:
| 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.
| jessaustin wrote:
| 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...
| progre wrote:
| 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?
| ArkanExplorer wrote:
| "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?
| curiousllama wrote:
| 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?
| CapitalistCartr wrote:
| Polynesians have the most average CCs of brain. There's no
| correlation between this and smart.
| nielsbot wrote:
| Might want to check your facts. Especially since you're citing
| this person: https://en.wikipedia.org/wiki/J._Philippe_Rushton
| aritmo wrote:
| 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.
| ArkanExplorer wrote:
| 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.
| vkou wrote:
| 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...
| [deleted]
| ben_w wrote:
| 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'.
| choxi wrote:
| > 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".
| BerislavLopac wrote:
| 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
| vmception wrote:
| 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.
| forgotmypw17 wrote:
| 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.
| EGreg wrote:
| 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?
| rickspencer3 wrote:
| 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.
| jjk166 wrote:
| 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.
| hirundo wrote:
| 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.
| frongpik wrote:
| 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.
| doggodaddo78 wrote:
| The first chapter of Diamond's _Guns, Germs, & Steel_ takes a
| crack at this.
| sebmellen wrote:
| I much prefer the stoned ape theory
| https://youtube.com/watch?v=Nxn2LlBJDl0
| karpierz wrote:
| 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.
| statstutor wrote:
| 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.
| TeMPOraL wrote:
| > _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.
| statstutor wrote:
| 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).
| jjk166 wrote:
| 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.
| tryonenow wrote:
| >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.
| statstutor wrote:
| > 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.
| vkou wrote:
| 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.
| cschwarm wrote:
| 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.
| rightbyte wrote:
| How about the opposite. Smart humans could hunt dangerous
| animals. The causality is not obvoius ...
| fearling wrote:
| This was my first thought as well.
| otabdeveloper4 wrote:
| A charitable way to put it. The more straightforward term is
| "just-so story".
| karpierz wrote:
| Thanks for pointing me to that term, I've been looking for a
| more succinct description for this.
| carlob wrote:
| It's not just a term it's also a book!
|
| https://en.wikipedia.org/wiki/Just_So_Stories
| Hermel wrote:
| Would a mechanism that selects for more intelligence
| automatically create evolutionary pressure into that direction?
| AnimalMuppet wrote:
| _If_ that proposed mechanism is actually operating in
| practice, and _if_ there are no other mechanisms that
| counteract it, then yes, it would.
| ajuc wrote:
| I wonder what caused dolphins to evolve their intelligence. I
| don't think they hunted underwater mammoths :)
| raincom wrote:
| It is called ad hoc explanation.
| statstutor wrote:
| Thanks, I didn't know about this:
| https://en.wikipedia.org/wiki/Ad_hoc_hypothesis
| economusty wrote:
| I don't believe that counts as science.
| DoofusOfDeath wrote:
| 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?
| busyant wrote:
| > 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...."
| DoofusOfDeath wrote:
| 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.
| jvanderbot wrote:
| 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.
| BiteCode_dev wrote:
| 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 ?
| jvanderbot wrote:
| 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.
| rory wrote:
| This is, at the very least, an interesting though experiment.
|
| We often suppose: (we can't find intelligent
| extraterrestrials)[?](there is a great filter ahead of us)
|
| But what if: (we have passed a great
| filter)[?](there aren't many intelligent extraterrestrials)
|
| That doesn't mean there aren't _other_ filters in our future.
| But it could help explain the Fermi Paradox. It also fits with
| the apparent dearth of marginally-intelligent and marginally-
| unintelligent species here on Earth with us.
| darkmarmot wrote:
| I fear the collapse that will accompany the Holocene Extinction
| is unfortunately ahead of us.
| testfoobar wrote:
| And is happening at a rate that is hard to fathom...
| mooneater wrote:
| > 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 wrote:
| 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.
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(page generated 2021-03-17 23:02 UTC)