Instead of speculating based on ignorance - which traps us in a loop of our own ignorance, and of each other's ignorance - let's break out of that loop and check with someone who has seen the evidence and knows it well:

* Fire use: ~1.42 million years ago is estimate, but uncertain

* Homo sapiens: Estimates range from 160,000 - 315,000 years ago.

* Controlled fire use: ~9,000 years ago; also uncertain

https://www.britannica.com/topic/Homo-sapiens

https://www.britannica.com/science/fire-combustion

Tip: If Britannica gives you a paywall, find the article via a search engine. Or maybe pay them - it's nice to have experts at your fingertips. The Homo Sapiens article is by the Curator of the Department of Anthropology at American Museum of Natural History.

Are you missing a zero? Anatomically modern humans are significantly older than 35,000 years.

It's plausible that a larger brain developed because it offered advantages. But later that brain was optimized without increasing in size.

For example, my current desktop computer is the same size as my stone age IBM PC.

There’s a reason we call them anatomically modern and not just humans. There is a period ~35kya where we get “Modern man” and it correlates with increased brain activity.

Things like “complex” cave paintings, tally marks etc take off right after (in evolutionary terms) as we marched towards farming and the written word

I do believe that "anatomically modern" includes brains. https://en.wikipedia.org/wiki/Brain_size#Variation_and_evolu...

Can you provide any sources for claims about brain size? I admit I'm not an expert, but I've never heard claims that brain size significantly increased in that period.

A few other facts that I can't say rule out what you're saying, but make it counter-intuitive:

Mitochondrial Eve was 150,000 years ago, Y Chromosome Adam was > 200000 years ago. Aboriginal populations in Australia are descended from populations that reached the island close to 50000 years ago. The Bering Strait was crossed close to 20000 years ago.

P.S. I do agree that saying fire might've been discovered within the past 10,000 years is unbelievable.

Edit: I belatedly see you might be talking about other changes to brains that aren't associated with increased brain size. Still, I'd ask whether there's evidence that anything about our brains changed 35,000 years ago, as opposed to us having accumulated knowledge and culture over time.

> A big reason humans developed our modern brains ~35kya is because of them cooking food (which makes digestion on proteins easier on the stomach)

Probably a bizarre question/thought experiment , and no way we'll know in our lifetime - if we start feeding cooked food to some animal, will it develop a larger brain?

Only if it _needed_ a larger brain to get that cooked food. Humans feed cooked food to ourselves, and our big brain helps us to discover and remember new sources of food, and how they need to be treated to become edible (e.g., https://en.wikipedia.org/wiki/Cassava#Toxicity). Without this pressure it’s hard to see how plentiful, nutritious food would do anything other than make the animal sedentary, slow, and stupid (e.g., to one degree or another, koalas, sloths, gorillas, modern humans).

No, there has to be selective pressure if we're not just talking about random drift. For hominids, sophisticated brains have been an incredibly rewarding evolutionary strategy despite the staggeringly expensive energetic costs they incur. Foraging is an intellectually demanding activity as we do it, so anything evolution can do from minimizing other expensive tissues (expensive tissue hypothesis) to high calorie oriented food selection to prosociality feeds back into improving fitness.

The timeline is pretty suspect there though. 35kya is far, far too late for any sort of behavioral modernity as that term is typically used.

My guess is that it would depend on the animal. Most carnivore stomachs are highly optimized for digesting raw meat. My layman's understanding is that because humans are fairly balanced omnivores, we get more benefit from cooking meat.

The pH of human stomach acid is on par with that of many scavengers, such as vultures.

Anthropological evidence indicates that early hominids, as they began their transition to a more carnivorous diet, were feeding on the left overs from other carnivorous predators - which would explain the need for such an extremely acidic stomach

Fascinating, does that mean vultures are just as susceptible to e.coli, salmonella, etc as we are? I always presumed they could handle "slightly spoiled" meat without food poisoning better than us.

Interesting!

perhaps (and i don't know) the added nutrition from eating cooked food had greater benefit at time T for individuals with slightly better brains via natural variation a la genetics/mutation...and if so they'd slightly be more active and slightly be more reproductive, correlating advent of cooked food with improving brains, but not as causally as suggested?

Just the timeline given here is very suspect, my understanding is human brains were roughly the same size they are today 35000 years ago. Did you mean 350k?

Has the causal and temporal relationship between cooking and modern brain development been firmly established? The last time I looked into the literature I could find (a decade ago), there seemed to be a tantalizing correlation but enough noise in the timing of cooking to place it well short of being an well-accepted theory. And the question of what constitutes a "modern brain" and when our ancestors had it was an even fuzzier area.

A lot of these things we don't have accurate timelines for because they're all pre-history. We find evidence of things, but no records.

keeping fire alive was a real thing way before making it ex nihili. so this wouldn't contradict the correlation with brain size. if it went or you could get it from your neighbor or long distance transport from natural sources.

is there a citation for that? i don't mean i think it's wrong, just want to learn more why you said that.