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Why are our brains shrinking?

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Re: Why are our brains shrinking?

#91

Post by renewiltord »

knownjorbist wrote: post #78
owenversteeg wrote: post #74

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 wish I could upvote this more. I would be willing to bet a number of such comments did not even read the article and responding based on impulse with their gripe about modern society du-jour.

A thing on HN you will see frequently is that someone will be told that X happened and they’ll explain confidently post hoc why.

Occasionally, they will misunderstand this as Y happening and they’ll explain that.

In the best universe, they will misunderstand X having happened as Y having happened and explain it even though Y did not happen.

The existence of this last characteristic makes me trust post hoc explanations very little. Explanations should make falsifiable predictions. It is easy to fit the facts with a false thesis.

Example: https://news.ycombinator.com/item?id=29005765

Re: Why are our brains shrinking?

#92

Post by Iv »

The domestication part makes the most sense in my opinion.

However, I only see attempts to explain that genetically. Aren't there environmental factors that can influence this measure?

Re: Why are our brains shrinking?

#93

Post by silisili »

owenversteeg wrote: post #74

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…

> Cutting-edge (heh) technology 70,000 years ago was the stone blade as well as the earliest known primitive art

I think it's important to remember that technology is highly, highly iterative. It's not like if Elon Musk were born 70k years ago we'd have cavemen with electric cars.

In fact, if all of us were somehow warped back in time that far, I fear we'd be even worse off. We know how to roll fiber optic networks and write ML algorithms, but we'd starve before figuring out how to chase down an animal, or know which berries to eat.

Re: Why are our brains shrinking?

#94

Post by exporectomy »

notriddle wrote: post #85
exporectomy wrote: post #77

Earlier quoted context omitted.

Do you have a real concern with eugenics or is it just because your culture demonizes it? We already have little bits of eugenics baked into law and culture. Why not a little bit more? It doesn't have to involve death camps.

Same reason so many people object to censorship: nobody can be trusted with that kind of power.

Is that really why eugenics is demonized? That the human race (not any living individuals) is giving up its freedom to some sort of fallible authority?

I guess, like censorship, people only object to an arbitrary subset of it. People love censorship of "really bad" ideas just as they love eugenics of "really bad" genes.

Most people seem happy with asserting our authority of gene selection over animals though :P Conservationism is that. Not to mention actual selective breeding and killing of course. Perhaps we rightly believe humans truly are capable of being benevolent arbiters of who gets to reproduce and who doesn't in animals.

Re: Why are our brains shrinking?

#95

Post by NoWizards »

owenversteeg wrote: post #74

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…

There is a recent news about elephants evolving to have no tusks... Something that is happening in a relatively short time span. I will no wonder if our modern trends (consuming anything to get pleasure and short-term rewards) will affect our brain size in a similar time span.

Re: Why are our brains shrinking?

#96

Post by ramblenode »

chernevik wrote: post #61

Perhaps it is female (or family) intelligence and impulse control driving the age at which a female paired off and had children. Paleolithic life expectancy was something like 22 to 33, and much of that after very high infant/maternal death rates. With such life expectancies, females would likely be bearing children at ages we today would find positively shocking. Simply surviving childbirth would be a huge selection…

> Paleolithic life expectancy was something like 22 to 33, and much of that after very high infant/maternal death rates.

This is a widespread belief but it is an urban myth. Most of the average mortality from the Paleolithic is weighted downward due to infant and childhood mortality. If you lived past 15 years there was a good chance you would grow old. A 2008 study found that once infant mortality was removed the average life expectancy was 70 to 80 years! [0]

> our ancestors wouldn't have the same hangups and cultural barriers humans have had for the past several millenia.

Citation needed. Rules over access to women is found across ancient societies and cultures. In patriarchal societies women are a valued good and bargaining chip between men, hence the cross-cultural dowry paid to the father. Promiscuity would have been even more problematic then than today because of small, tight-knit communities where paternity controversy could cause a major social disruption in the clan.

[0] https://www.ancient-origins.net/news-evolution-human-origins...

Re: Why are our brains shrinking?

#97

Post by matheusmoreira »

vlovich123 wrote: post #76
matheusmoreira wrote: post #52

Earlier quoted context omitted.

Sounds like we need to take control of this evolutionary process and start engineering it. Just because we are no longer required to use these abilities on a daily basis doesn't mean we don't want them. Evolution can go to hell with its "pressures", humanity is supposed to get better over time, not worse.

You're making a value judgement like "better" and "worse" as if there was a clear global optimum that you can reach. Why do you assume that's the case? Let's assume there even is a global optimum. Why do we think this global optimum would be invariant on environment? We have clear examples of species that fail to adapt to their changing environment quickly enough dying off. If you took the survivors of a change and t…

Surely having sharper and more intelligent humans is an objectively better uncontroversial outcome. If there's even a chance that our environment is somehow downregulating important features such as intelligence, we must find a way to reverse that process.

Re: Why are our brains shrinking?

#98

Post by snek_case »

lumost wrote: post #81
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…

Alternately, big brains are recessive/selected against in all circumstances except those from 6mya to 70kya. We've generally removed most selective pressure at this point, if having big brains is due to a combination of recessive traits we'd expect brain size to start shrinking.

I was going to say: maybe it's because we're so successful? We dominate our environment so well that we've made the world a much less threatening place, and so it's not as difficult to survive in the world anymore. Less selective pressure means we end up with a less selected population.

I don't want to turn this into a political commentary, but the modern age is an extreme example of this. You could be the kind of person who doesn't finish high school and can't keep a job, a deadbeat, but still manage to have multiple kids. Even if you don't take care of them, someone else will ensure that your kids survive. Long ago, not being able to are and provide for your kids probably meant that they died.

IMO, as we keep making the world increasingly more safe and comfortable, we might have to resort to genetic engineering. Otherwise, it might be inevitable that more and more genetic disorders will arise, just because we're able to keep people alive with all kinds of illnesses that would have been fatal before. People can argue about the ethics all they want, but it seems inevitable.

Re: Why are our brains shrinking?

#99

Post by vmception »

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…

The article touches on that too.

It is pretty comprehensive about a variety of going theories and doesn’t make the mistake of choosing any single one of them as the “because”.

Re: Why are our brains shrinking?

#100

Post by herval »

NoWizards wrote: post #95
owenversteeg wrote: post #74

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…

There is a recent news about elephants evolving to have no tusks... Something that is happening in a relatively short time span. I will no wonder if our modern trends (consuming anything to get pleasure and short-term rewards) will affect our brain size in a similar time span.

That was very much guided evolution though - elephants without tusks get spared, the others get killed for the tusks. There’s nothing like that happening with humans at a population scale, outside the realm of conspiracy theories
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