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Why are our brains shrinking?

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Re: Why are our brains shrinking?

#41

Post by jacquesm »

algebraically wrote: post #30
lordnacho wrote: post #24

Earlier quoted context omitted.

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.

Because we no longer need to run away from predators and process information at the same rate we'd need to in a more wild enviornment. The survival pressures of our ancestral environment are no longer relevant. We've essentially destroyed and driven to extinction every other predator on the planet and now the only selective pressure is adaptation to the human created environment which is much nicer and simpler than t…

> and process information at the same rate we'd need to in a more wild enviornment

If anything that rate of processing has gone up, not down.

Re: Why are our brains shrinking?

#42

Post by Asooka »

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…

Hm, then shouldn't people who live in tribal societies as hunter gatherers have bigger brains still? Has anyone studied that?

Re: Why are our brains shrinking?

#43

Post by algebraically »

jacquesm wrote: post #41
algebraically wrote: post #30

Earlier quoted context omitted.

Because we no longer need to run away from predators and process information at the same rate we'd need to in a more wild enviornment. The survival pressures of our ancestral environment are no longer relevant. We've essentially destroyed and driven to extinction every other predator on the planet and now the only selective pressure is adaptation to the human created environment which is much nicer and simpler than t…

> and process information at the same rate we'd need to in a more wild enviornment If anything that rate of processing has gone up, not down.

And most of it has been offloaded to computers (big data, deep learning, etc). I don't think we're going to have "mentats" any time soon.

Re: Why are our brains shrinking?

#44

Post by alcover »

JKCalhoun wrote: post #14
chrisco255 wrote: post #6

Earlier quoted context omitted.

From the article it indicates this shrinkage began 70K years ago, or 65K years before writing. In addition, vast majority of the population didn't know how to read or write until 100-150 years ago.

I definitely move through life seemingly in a mechanical fashion. I suspect in the wild I would be alert, all attention, always anticipating, planning.

  in the wild I would be alert
I am when I hike alone. Not super alert - since there are few dangerous animals in my country - but alert still.

Also, you are very alert when you walk in bad neighbourhoods.

Re: Why are our brains shrinking?

#45

Post by akomtu »

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…

Domestic animals have safe, boring and predictable environment. It's expected that they'd simplify their brain - the organ that consumes so much energy. If domesticated animals started playing chess, that would be a different story, but they spend their life mindlessly walking between a food dispenser and a litter box, taking naps in between.

Re: Why are our brains shrinking?

#46

Post by algebraically »

Asooka wrote: post #42
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…

Hm, then shouldn't people who live in tribal societies as hunter gatherers have bigger brains still? Has anyone studied that?

I don't know. That's a good question but most modern humans are essentially clones so I don't think there is going to be much difference. [1][2]

1: https://www.nationalgeographic.org/media/genetic-bottleneck/

2: https://en.m.wikipedia.org/wiki/Toba_catastrophe_theory

Re: Why are our brains shrinking?

#47

Post by scoofy »

akomtu wrote: post #45
scoofy wrote: post #39

Earlier quoted context omitted.

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…

Domestic animals have safe, boring and predictable environment. It's expected that they'd simplify their brain - the organ that consumes so much energy. If domesticated animals started playing chess, that would be a different story, but they spend their life mindlessly walking between a food dispenser and a litter box, taking naps in between.

>they'd simplify their brain

This is not how evolution works! They are not in control of their breeding. Evolution is not some intelligent agent with goals. It is like a river, responding to to the path of least resistance in reproduction.

Intelligence and/or brain size not a dominant evolutionary factor unless they are specifically bread for intelligence and/or brain size. Domesticated animal's dominant evolutionary qualities have nothing to do with the animal preferences for mating, thus brain size in fairly arbitrary, and we should suspect it to be some sort of drift, rather than rationally getting smaller.

Re: Why are our brains shrinking?

#48

Post by screye »

Assuming it has to do with evolution, it would mean that there are clear breeding preferences that where folks with 'smaller brain' mutations' are likely to reproduce at higher rates than your average person. ( Idiocracy Theory ?)

Is it possible that there is long term development of emergent traits in a species, through a process that is not evolution ?

I don't buy the domestication hypothesis, because I see no proof that aggression has been disincentivized over what we know about ancient human history. There might be unintended consequences, where those who don't go to war are more likely to live and therefore reproduce, leading to propagation of non warring = low-aggression genes.

Lastly:

> This may mean that smaller brains are being naturally selected for. Of course, this hypothesis relies heavily on premises that are both not confirmed and highly controversial.

When the only reason to reject a hypothesis, is that it is controversial, I am inclined to assign it a higher likelihood.

Re: Why are our brains shrinking?

#49

Post by jacquesm »

algebraically wrote: post #43
jacquesm wrote: post #41

Earlier quoted context omitted.

> and process information at the same rate we'd need to in a more wild enviornment If anything that rate of processing has gone up, not down.

And most of it has been offloaded to computers (big data, deep learning, etc). I don't think we're going to have "mentats" any time soon.

You have this backwards. We are dealing with orders of magnitude more information than we did in ancient times, and we are required to remember a good chunk of it and to be able to recall and use it at a moments notice.

Computers are a big factor in generating all of that information, even if they help process some of it the net effect is a huge surplus.

Re: Why are our brains shrinking?

#50

Post by algebraically »

jacquesm wrote: post #49
algebraically wrote: post #43

Earlier quoted context omitted.

And most of it has been offloaded to computers (big data, deep learning, etc). I don't think we're going to have "mentats" any time soon.

You have this backwards. We are dealing with orders of magnitude more information than we did in ancient times, and we are required to remember a good chunk of it and to be able to recall and use it at a moments notice. Computers are a big factor in generating all of that information, even if they help process some of it the net effect is a huge surplus.

I don't think I have it backwards. I don't remember anything or know much about the world in general terms. I just know and remember enough key phrases for google to give me the answers when I need them which requires very little cognitive effort on my part. [1]

1: https://www.psychologytoday.com/intl/blog/the-athletes-way/2...

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