Cooking food breaks down the cell walls and so makes it much easier to digest. So you can get more of the calories out of the food you consume. You spend less time gathering and eating and free up time for thinking.
I think it's the other way around. We got bigger brains in the first place because our ancestors discovered fire and were able to eat cook foods that provide more calories. Therefore they progressively were able to sustain larger and larger brains. A gorilla for example has one of the largest brains for primate and they need to spend most of their days foraging in order to function. A human brain would be impossible to sustain without cooked foods.
( I swear I need of of those [0], my head - short hair nonetheless - is sweating like hell in the night )
[0] https://www.amazon.com/Mediflow-1006-06-Original-Waterbase-P...
How do we explain the survival of people that eat only raw foods even today? Wouldn't that argue against your theory?
I suppose we're speaking about a population and that there will be individual exceptions. But even in a population, shouldn't raw food eaters die sooner or be worse off than cooked food eaters on average?
I'm not in favor or opposed to the person you're responding to. Just thinking about how humans eating a raw diet are different from other animals doing so.
"Survival," in the evolutionary sense, doesn't just mean "living into old age" but "reproducing successfully", which paused menses preclude.
As far as I know, that's not how evolution works. You don't get a feature just because you can sustain it. There's a random mutation and everybody who doesn't get it dies or fails to have offspring.
So in your theory, what was the mutation (or phenotype) and what was the environmental pressure that killed off the non-mutants? And how does it relate to using fire?
However, humans do have much larger brains than other primates, and those brains grow very fast immediately after birth. My theory is that after the advent of cooking, human brains were able to increase in size thanks to the increased dietary energy density of our new diet. Human breasts then had to increase in size in proportion with the nutritional requirements of those infant brains, which had to grow faster than previously.
My theory still works if initially, female pre-humans with larger milk glands were able to better feed their young and so had higher survival rates, while male pre-humans evolved to prefer larger milk glands. After a point, runaway sexual selection caused breast size to increase independently from the pressure on milk production.
That's the distorted popular version. The more common scientific version, AFAICT, is that they evolved in certain other upright primates to resemble swellings in the genital/buttock region of non-upright forbears and provide similar sexual signalling.
> Human breasts then had to increase in size in proportion with the nutritional requirements of those infant brains, which had to grow faster than previously.
This speculation would make sense if there was a relation between the quantity of fatty tissue which determines breast size and milk production. But, there isn't, so...
I would guess that the reason they're large and the reason they're permanent are related. One causal chain might be (permanent breasts -> males like breasts -> breasts grow), but others are possible. I suppose it might be that non-permanent breasts wouldn't be able to grow to the size they need to be, for whatever reason they need to be that size?
(In case it wasn't clear, I have no expertise in this area, and you shouldn't listen to what I have to say.)
One interesting possibility is that breast tissue influences maternal drive. A combination of neural activity and hormone secretion is possible and would do the trick nicely.
Interesting that intelligence bootstraps like this. Get smart enough to use fire and that allows you to grow more neurons and get smart enough to make... wheels? Computers? What's the next leap after fire?
Next, you'd want cutting tools to separate your food into clothes parts and eating parts. Use bladders for storing water, which (along with clothes) allows for safer travel and bigger hunting/gathering ranges. Cutting tools also help make good weapons.
With a larger range and easier hunting, you won't have to be as nomadic to find food, so you can start permanent settlements. Find somewhere where plants will grow with regular flooding. Learn to make clay brick and pots in your fire, and you can now store food, seeds, and water. More time now to figure out how to control the flooding process so you lose less crops and can grow on drier land.
Maybe language? That surely changes our brain structure? Did that come before fire? We know that other animals have rudimentary language, so is language a precursor to fire? Is it a prerequisite for fire?
Sander van der Leeuw, of the University of Arizona / Santa Fe Institute, is among the researchers looking at this. Part of the process is tracked through the complexity of stone tools, which (he argues) is related to short-term working memory and the number of items that can be maintained there.
As to causality:
* Fire, cooking, and food preparation: increase food availability, decrease the uncertainty and energy required for food gathering.
* Tools, language, and simple structures: cooperative and complex arrangements. Possibly not so much the cause of mental development as a selection filter: those with better brains can work together in more complex societies.
* Agriculture, writing, cities: This pretty much sparked like a fire and took off immediately, throughout the Asian-African-European supercontinent, and, somewhat less spectacularly, in parts of the Americas.
* More recent developments may not have occurred over a sufficient period of time as to be profoundly evolutionary, though I wouldn't dismiss the thought. Still, the process is clearly cumulative.
You might also like to poke around at the History of Information website:
http://www.historyofinformation.com/
Also David Christian's "Big History" concept:
Sheepdogs and their ability to control a mob of sheep always seemed to me to be pretty damned smart...