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Why are our brains shrinking?

usfblogs.usfca.edu

141–150 of 199 posts

Re: Why are our brains shrinking?

#141
Like others have said, bigger doesn't necessarily mean smarter or more intelligent.

I like to think of a scenario comparing the first commercially available computers being the size of rooms, now we have exponentially more computing power in the size of the palm of my hand.

Re: Why are our brains shrinking?

#143

It seems like the majority of the comments are not taking into account that this trend began approximately 70,000 years ago - slightly before the various things people here are blaming such as TikTok, Google, writing, Javascript and Twitter. Cutting-edge (heh) technology 70,000 years ago was the stone blade as well as the earliest known primitive art. An interesting guide whenever you're trying to put this kind of th…

I think the answer is the same reason the male brain is larger than the female brain on average. The part of the brain that handles fighting. It's a pretty large part of our brains.

The reptilian hindbrain that handles violence isn't needed nearly as much now that we have society and civilization. It's shrinking.

Re: Why are our brains shrinking?

#144

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…

Relevant http://www.paulgraham.com/boss.html

Re: Why are our brains shrinking?

#145

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…

I think the only thing I really quibble a bit with is the description of "dumber". Our "domestication" has historically been more that we've gone from a generalist species to a specialist society. With that, things that were previously probably a boon for survival and reproduction become less so (For example, quick reaction times don't matter so much when you have a city wall to keep out predators and a backup huntin…

> Sort of like how humans might be evolving towards color blindness because being able to tell the difference between red and green doesn't necessarily increase our ability to have children.

Doesn't this hold true for "dumbness" as well? Being dumb is no longer an obstacle in having a reproductive success.

I wouldn't be surprised if there was a peak in the reproduction rate bell curve around IQ 80-90.

Re: Why are our brains shrinking?

#147

Earlier quoted context omitted.

The HN rule about not being able to ask if someone read the article or imply/suggest that they did not is the worst rule on the site, because it encourages this behaviour :(

HN needs a lot of rule changes. The narrative of "dang is a great mod" and "HNs rules are actually great" flys in the face of repeated examples of complete incompetence/corruption within HN and it's moderation practices. (E.g. calling discussion about political topics dang doesn't like "ideological flame bait" and deleting the posts.)

Could you give some specific examples?

Re: Why are our brains shrinking?

#148

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…

I knew a professor that loved getting freshmen classes because he could disabuse them their Yankee in king Arthur's court ideas about how easy it'd be to bring technology back to the past. He had a whole slew of experiments that would explore path dependence and the difficulties of creating technologies with the available resources. Nominally this was to help them not underestimate the intelligence of early humans, b…

I feel like the pendulum has swing too far in the other direction on this topic, actually. Yes people in the past weren't dumb, and shouldn't be under-estimated, but even a normal person could provide huge gains to any pre-modern society. Their understanding of mathematics, biology, evolution, medicine, astronomy, economics, reading+writing, organization, etc. are immeasurably valuable. I don't think people appreciate how much "ideas" are, in some sense, a kind of technology in themselves. Yes you probably couldn't make yourself a queen of the land with your advanced knowledge, but you could massively improve this society in fundamental ways. Like get infected with cowpox if you want to get vaccinated (a term meaning of or from cows btw!) against small pox.

>It's likely that ancient humans were adept at many of these things, like salt preservation, warm clothing, contraception, spun fibers, and boats. Many of the others (agriculture, wheels, etc) simply wouldn't make sense outside their native cultural contexts.

For people this primitive, even elementary metalworking would be revolutionary. Yes you'd have to do a bit of tinkering to work out the kinks, but iron ore pre-modern-extraction was everywhere, and once you have the foreknowledge that heat special rock -> smash into shape -> better-than-rock tool it's not hard to figure your way to something groundbreaking.

I do think you'd be limited in how much you could change things by how far back you go, but mostly due to human life span. The more new technologies you need to personally 'invent' the longer this stuff takes, as you'd need to experiment with on-the-ground resources and techniques until you can successfully realize your conceptual understanding. I know what a blast furnace is, and because I have the key concepts I can eventually build one with some trial and error. But it would take years if I had to start from just sticks and sand.

Re: Why are our brains shrinking?

#149

Earlier quoted context omitted.

The HN rule about not being able to ask if someone read the article or imply/suggest that they did not is the worst rule on the site, because it encourages this behaviour :(

HN needs a lot of rule changes. The narrative of "dang is a great mod" and "HNs rules are actually great" flys in the face of repeated examples of complete incompetence/corruption within HN and it's moderation practices. (E.g. calling discussion about political topics dang doesn't like "ideological flame bait" and deleting the posts.)

dang being great and HN rules being great are two separate claims. It's entirely possible that someone agrees with one of them and disagrees with the other. For example, me. I disagreed with one of the rules. I spoke to dang about it and shared why. He listened to me, shared his perspective on why the rule exists and went out of his way to resolve the issue for me specifically.

He strives to lower the temperature of discussions that get too heated. He tries (and mostly succeeds) to get folks to stay on topic and civil. He keeps the site free from trash or astro-turfing. And he does all this alone.

> complete incompetence/corruption within HN

This is a strong claim. If you have evidence of it, show us. Or retract it.

Re: Why are our brains shrinking?

#150
post #105

Any potential explanation would have to account for the fact that this happened around the world, not only in certain sub-populations. The article isn't clear on whether it began at different times in different places, possibly because the data isn't complete enough. A start date of 70,000 years ago suggests it has something to do with human exodus from africa that occurred around that time. The difficulty is that ev…

The article makes reference to this phenomenon being global:

> Yuval Harari says that the worst choice in the history of human societies is when humans made the transition from nomadic hunter-gatherers to sedentary farmers. With this, humans became much more susceptible to malnutrition, disease, and famine. Their grain-heavy diets lacked critical nutrients that are essential to proper brain function. But, we see brain shrinkage in the aboriginal people of Australia and South Africans, who never succumbed to agriculture until recent times, and we see the same amount of shrinkage in these populations as well.

It's possible as you say that founder effects and reverse migration and interbreeding could account for this, but an alternative theory is that trade emerged as a driving force of human activity, incentivising new behaviours, and so ultimately it was memetics that changed the selection parameters that shrunk brain sizes

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