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The human brain grew as a result of the extinction of large animals: new paper

phys.org

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Re: The human brain grew as a result of the extinction of large animals: new paper

#91

Post by Maursault »

airhead969 wrote: post #8
tashoecraft wrote: post #3

Earlier quoted context omitted.

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?

Re: The human brain grew as a result of the extinction of large animals: new paper

#92

Post by yellowapple »

ajuc wrote: post #43
karpierz wrote: post #14

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.

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).

Re: The human brain grew as a result of the extinction of large animals: new paper

#93

Post by yellowapple »

marshray wrote: post #70
tashoecraft wrote: post #57

Earlier quoted context omitted.

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 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".

Re: The human brain grew as a result of the extinction of large animals: new paper

#94

Post by T-A »

ajuc wrote: post #43
karpierz wrote: post #14

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.

I wonder what caused dolphins to evolve their intelligence. I don't think they hunted underwater mammoths :)

https://en.wikipedia.org/wiki/Killer_whale#Mammals_and_birds

https://en.wikipedia.org/wiki/Killer_whale#Intelligence

Re: The human brain grew as a result of the extinction of large animals: new paper

#95

Post by vagrantJin »

TeMPOraL wrote: post #51
statstutor wrote: post #37

Earlier quoted context omitted.

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…

> 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 engi…

Yeah.

We are just primates, doing what all primates do just with a lot more suave and panache

Not much more really.

Re: The human brain grew as a result of the extinction of large animals: new paper

#96

Post by sgt101 »

Schmools wrote: post #15
sgt101 wrote: post #6

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 eviden…

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!

Re: The human brain grew as a result of the extinction of large animals: new paper

#97

Post by jiofih »

_RPL5_ wrote: post #54

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 h…

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.

Re: The human brain grew as a result of the extinction of large animals: new paper

#98

Post by jiofih »

matznerd wrote: post #87
BerislavLopac wrote: post #77

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…

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 mo…

Fantastic. Here is your Nobel prize for this discovery:

Re: The human brain grew as a result of the extinction of large animals: new paper

#100

Post by hntrader »

TeMPOraL wrote: post #51
statstutor wrote: post #37

Earlier quoted context omitted.

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…

> 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 engi…

Mutation is completely random and selection mostly isn't. Many confuse mutation with selection.
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