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Why are our brains shrinking?

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Re: Why are our brains shrinking?

#31

Post by tomjen3 »

algebraically wrote: post #18
FormerBandmate wrote: post #11

Earlier quoted context omitted.

Domesticated by whom? How?

It's possible for an animal to domesticate itself. This is one of the theories for how wolves were domesticated. It's not that humans did anything special to domesticate them but that wolves started hanging around humans and eating the scraps that were left over at campfires and other human habitation sites. Eventually the less fearful and tame wolves became human companions. Once people realized they could hang out…

I did some research into this a couple years ago. There is an interesting theory that we didn't domesticate wolves, but that wolves domesticated us. For one, wolves naturally are very intelligent and pack hunters, so they could have used humans as a hunting partner. For another point, we domesticated wolves way before anything else (atleast 20000 years ago) and that makes no sense since every other animal we domesticated (goat, horse, chicken, etc) will eat pretty much anything and is only of very limited threat to us, whereas wolves are carnivores (very expensive to maintain) and extremely dangerous.

However, if wolves domesticated us as hunting partners, then this starts to make a lot more sense. We didn't need to first learn domestication on easier species, the danger was limited and our hunting would be so much more effective that it was worth the premium.

It also explains why we have the concept of werewolf and why some people have been charged with turning into wolves to be successful in hunting, but never any other animal (there are no cases of ware eagles/falcons). There is something primeval deep inside us that associates wolves with successful hunters.

I find the theory neat, I am not convinced it is true.

Re: Why are our brains shrinking?

#32

Post by reggieband »

I'm sure some are aware but in case you are not, Lex Friedman podcast recently had an episode with Richard Wrangham [1] where they discuss this. Wrangham is a primatologist that studied alongside Jane Goodall. His theory suggests human's show signs similar to what we see in other species that have been domesticated. This includes smaller face/jaws and smaller brains.

1. https://www.youtube.com/watch?v=YJF01_ztxwY

Re: Why are our brains shrinking?

#35

Post by algebraically »

tomjen3 wrote: post #31
algebraically wrote: post #18

Earlier quoted context omitted.

It's possible for an animal to domesticate itself. This is one of the theories for how wolves were domesticated. It's not that humans did anything special to domesticate them but that wolves started hanging around humans and eating the scraps that were left over at campfires and other human habitation sites. Eventually the less fearful and tame wolves became human companions. Once people realized they could hang out…

I did some research into this a couple years ago. There is an interesting theory that we didn't domesticate wolves, but that wolves domesticated us. For one, wolves naturally are very intelligent and pack hunters, so they could have used humans as a hunting partner. For another point, we domesticated wolves way before anything else (atleast 20000 years ago) and that makes no sense since every other animal we domestic…

Ya, I also don't know if it's true or not. I was just making the point that an animal can domesticate itself by changing its environment and then adapting to the new environment in a way that ends up being essentially a self imposed domestication process.

Re: Why are our brains shrinking?

#36

Post by playpause »

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.

“Use it or lose it” applies in evolution, because of energy usage, but also because of complexity. More features means more things to go wrong, more options for cancers, etc.

Re: Why are our brains shrinking?

#37

Post by dymk »

rackjack wrote: post #29
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.

The brain itself is the evolutionary pressure. It is often repeated that the brain takes ~20% of our body's energy despite being ~2% of our body's mass. If there is no need to have a brain so large (due to a lack of predators) it is beneficial to shrink it.

It's beneficial to lower the brain's calorie intake it if it results in higher reproductive fitness. But like GP said, we have plenty of calories, more than we've had compared to the entire history of humanity. So it doesn't naturally follow that lower calorie brains are higher fitness in 2021.

Re: Why are our brains shrinking?

#38

Post by Robotbeat »

rackjack wrote: post #29
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.

The brain itself is the evolutionary pressure. It is often repeated that the brain takes ~20% of our body's energy despite being ~2% of our body's mass. If there is no need to have a brain so large (due to a lack of predators) it is beneficial to shrink it.

Beneficial how? Reduction in calories? We tend to have diseases of excess calories in the developed world now. If anything, the greater brain metabolism may actually help by burning some of those excess calories off…

Re: Why are our brains shrinking?

#39

Post by scoofy »

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 are so many things to unpack here. What do we mean by "dumb" and which parts of the brain are being used, and how their size relates to their usefulness. I think it would be extremely difficult to argue any of these claims on their face beyond: small brain -> less brain function, which is extremely spurious.

Homo neanderthalensis had notably larger brains than us, yet they did not survive. Hardly an argument for the idea of greater intelligence -> greater brain size. AFAIK, specific areas in the prefrontal cortex is the primary point of interest when it comes to intelligence, and it's a relatively small section of the brain compared, say, to the visual cortex.

https://www.discovermagazine.com/planet-earth/neanderthal-br...

Finally... the most absurd of all the ideas packed in here is that natural selection for smaller brain size would even be a thing. Human mating is openly available for study, I see little-to-no argument for this being plausible beyond some sort of idiocracy world (is this the domestication thesis you hold? I see in the article they are treated separately), which is genuinely problematic. Possibly that certain types of brain sizes are predisposed to certain behavioral patterns. However, the idea that there is even a single evolutionary pattern for billions of humans is pretty ridiculous. We don't have evolutionary islands like other animals do.

Re: Why are our brains shrinking?

#40

Post by 55873445216111 »

FredPret wrote: post #25
MaxGanzII wrote: post #17

Whales have brains which physically are much, much larger than a human brain; size does not directly equate to intelligence. Note also brains are extremely expensive, physiologically, to maintain. It may simply be we are evolving to be more efficient.

Maybe whales are brilliant

https://youtu.be/h02a2HSB58M
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