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Why are our brains shrinking?

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Re: Why are our brains shrinking?

#171

Post by owenversteeg »

pawelmurias wrote: post #156
owenversteeg wrote: post #103

Earlier quoted context omitted.

If an intelligent modern person with some knowledge of history was sent back to 70,000 years ago (70 kya) we'd probably be able to bring significant help to the group - assuming we were accepted into the group and not immediately killed by our ancestors in peak physical condition. Personally, I'd attempt to introduce: - art and culture from the far future (flutes, 42 kya; figurative art, 40 kya) - Simple ovens (29 ky…

> peak physical condition A lot of our ancestors where not in a particularly good physical condition because of how horrible their nutrition is.

Look at prisons with bad nutrition and you’ll notice a large amount of people with some serious muscle mass. If you’re getting regular, very intense exercise (as you would need to as a hunter-gatherer) you’re in the top x% of the world population by fitness, no matter if you’re slightly nutrient deficient. Furthermore, we have at least some reason to believe that prehistoric populations weren’t so badly fed that it led to physical issues - they regularly reached heights equaling that of humans in recent years, far taller than the poorly fed people in e.x. medieval Europe.

Furthermore, modern humans have plenty of disease and issues caused by our modern environment that would render us far weaker 70 kya. Near/farsightedness, teeth issues, diabetes, obesity, repetitive stress injuries, etc. are entirely modern issues. Then look at the comforts we’ve gotten used to (shoes, clothing, soap, a too-clean environment for our immune system etc) - and I have no doubt that a modern human would be in far, far worse shape for the prehistoric life than your average person 70 kya.

Re: Why are our brains shrinking?

#172

Post by hchasestevens »

scoofy wrote: post #39
algebraically wrote: post #5

Because we are being domesticated. Domesticated animals are all dumber than their wild counterparts. Every wild animal that ends up being domesticated ends up with a smaller brain. I should rephrase and maybe say that this doesn't necessarily mean the animals get dumber but they definitely change in the process of domestication and a smaller brain is one of those adaptations. [1] > The reduced amount of white matter…

Whoa... whoa... let's unpack all the intense presuppositions you're packing in here: "Domestication" is just a word for a natural evolutionary processes in a symbiotic system. The concept that "domestication" is like, actually a thing apart from evolution is a vastly more difficult idea to parse than it appears on it's face. >Domesticated animals are all dumber than their wild counterparts. I mean... again... there a…

> "Domestication" is just a word for a natural evolutionary processes in a symbiotic system. The concept that "domestication" is like, actually a thing apart from evolution is a vastly more difficult idea to parse than it appears on it's face.

In mammals, there is a well-established "domestication syndrome" with a specific proposed underlying mechanism and associated symptoms, including many observed in humans in comparison with other hominids (smaller jaws/muzzles, smaller teeth, smaller brain, greater docility). See https://www.genetics.org/content/197/3/795#skip-link for more information.

Re: Why are our brains shrinking?

#174

Post by helge9210 »

thro1 wrote: post #155
algebraically wrote: post #5

Because we are being domesticated. Domesticated animals are all dumber than their wild counterparts. Every wild animal that ends up being domesticated ends up with a smaller brain. I should rephrase and maybe say that this doesn't necessarily mean the animals get dumber but they definitely change in the process of domestication and a smaller brain is one of those adaptations. [1] > The reduced amount of white matter…

Is there some study about brain sizes of kindergarten and free-range kids?

I've read some articles about brain complexity of wolves depending on complexity of their habitat.

Re: Why are our brains shrinking?

#175

Post by helge9210 »

lordnacho wrote: post #24
algebraically wrote: post #5

Because we are being domesticated. Domesticated animals are all dumber than their wild counterparts. Every wild animal that ends up being domesticated ends up with a smaller brain. I should rephrase and maybe say that this doesn't necessarily mean the animals get dumber but they definitely change in the process of domestication and a smaller brain is one of those adaptations. [1] > The reduced amount of white matter…

Why is there evolutionary pressure for the brain to shrink? We seem to have enough calories to feed our brains, and we're not beholden to some master species that needs to economize.

> Why is there evolutionary pressure for the brain to shrink?

Less energy demand, I guess.

Re: Why are our brains shrinking?

#176

Post by watwut »

owenversteeg wrote: post #171
pawelmurias wrote: post #156

Earlier quoted context omitted.

> peak physical condition A lot of our ancestors where not in a particularly good physical condition because of how horrible their nutrition is.

Look at prisons with bad nutrition and you’ll notice a large amount of people with some serious muscle mass. If you’re getting regular, very intense exercise (as you would need to as a hunter-gatherer) you’re in the top x% of the world population by fitness, no matter if you’re slightly nutrient deficient. Furthermore, we have at least some reason to believe that prehistoric populations weren’t so badly fed that it l…

Prisons with low calories nutrition have weak thin people in them. Muscles don't grow of you don't eat protein and sacharids - no matter how much you exercise.

You can have sucky nutrition for lack of vitamins etc and those will eventually leave you in bad physical condition. Even if you gain muscle mass temporary, damage to health will be real.

Hunter gathrer also don't have reason to bulk up unlike those prison guys.

Re: Why are our brains shrinking?

#177

Post by SideburnsOfDoom »

j9461701 wrote: post #169
SideburnsOfDoom wrote: post #161

Earlier quoted context omitted.

> Their understanding of mathematics, biology, evolution, medicine, astronomy, economics, reading+writing, organization, etc. are immeasurably valuable. You could tell them that disease is caused by tiny animals, and that the earth is a sphere that orbits the sun, but getting them to believe you is a another thing. And making use of it yet another. You won't introduce quarantine just because of germ theory: book of L…

> You could tell them that disease is caused by tiny animals, and that the earth is a sphere that orbits the sun, but getting them to believe you is a another thing. I can find a cholera outbreak, and tell whoever will listen to stop drinking water from the local wells and eating from the local markets. Go to another part of the city for water and food. Those who listen, even if only one, will be my proof. I can also…

> I can find a cholera outbreak, and tell whoever will listen to stop drinking water from the local wells ... Those who listen, even if only one, will be my proof.

Results with diseases have a fair amount of chance, as we should all know by now. It might go as you say, it might not. Your disciple might leave and get cholera soon after due to exposure beforehand. A person who stayed and didn't get cholera might attribute their success to the manner in which they prayed. Or your guy's success to the manner in which they prayed.

It's hard to falsify the assertion that "they were not stricken because they were righteous / said the correct prayer", and "statistical significance" is not a dramatic or obvious thing to convey.

Re: Why are our brains shrinking?

#178

Post by newaccount74 »

My guess is that average individual brain size and intelligence just isn't as important in collaborative society. Once you start sharing knowledge (orally at first, written later), you don't need everyone to figure everything out on their own.

There's a also a huge variation in human brain size. [1] suggests almost a factor 2. I don't know if variation was similar 70.000 years ago.

[1]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4262916/

Re: Why are our brains shrinking?

#179

Post by vlovich123 »

matheusmoreira wrote: post #166
hawk_ wrote: post #120

Earlier quoted context omitted.

> Surely having sharper and more intelligent humans is an objectively better uncontroversial outcome What if there's a level of intelligence above which humans decide not to reproduce?

I question the intelligence of a human species that does not reproduce.

By what metric are you making the claim that humanity does not reproduce?

To my eye we’ve simply unlocked medical science and have taken control of reproduction to the point where it’s not critical to the species for everyone to reproduce. I’d be more concerned about all the plastics and chemicals that are now circulating in our bodies slowly decreasing our ability to reproduce than us as a species being too dumb to reproduce. That position just doesn’t have an existence proof point (no pandas don’t count because while it’s a funny pop meme, all evidence suggests they just can’t/won’t mate in captivity and it’s environmental for them).

Re: Why are our brains shrinking?

#180

Post by lostmsu »

leetcrew wrote: post #115
lostmsu wrote: post #110

Earlier quoted context omitted.

While the first one is probably really wrong, the other two are clearly fine. Imagine a unique cat with an IQ of human. Would you say it is more worth to society, than any other cat? Probably so. Is there a magic IQ threshold that renders other cats not as worthy as humans to not be given the same kind of resources? In a way yes, as you would draw a line. Intelligence is what makes humans humans.

I do love cats, but it's not clear to me what an extremely high IQ cat would be useful for. I suspect it would fall somewhere between lethal and unusually annoying.

At the very least they should be able to solve Mechanical Turk tasks.
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