Indeed, so the point remains the same, humans are natural hunters who followed large migratory species until they developed agriculture.
Humans are quite ill-equipped to consume the vegetal biomass of a particular enviroment, but specially the perennial forests.
Again, which climate has an "abundance" of biomass that humans are adapted to consume? we are obviously quite ill equipped for a jungle enviroment. For once we cant climb for shit, we cant eat grass or anything of the like either, if we had evolved in perennial forests we wouldnt had evolved like we did, we would had stayed as chimp-like or gorillas-like hominids..
Hominids made several attempts to colonize winter climates, these hominids died out during major glaciations or driven out by us.
Humans also didnt colonized the northern climates until the neolithic age so we didnt "evolved" in the cold climates. Paleolithic europeans lived in the warmer parts of Europe hunting the abundant game (just like paleolithic humans everywhere) and werent really "physically" adapted to the cold, unlike the European Neandertal who did evolved physically to survive in the cold.
That doesnt validates your conclusion that cold adaptation required an innate physical brain adaptation, because several hominids managed to populate regions all over Eurasia before the coming of the modern man, and none showed levels of intelligence (as measured by the complexity of tools or the presence of arts) as the modern man, they simply adapted physically to the regions.
Respectfully, you're all over the place here on a number of these objections, and you're just objecting, rather oddly, to some otherwise provisional truths about our evolutionary history.
First of all, it seems like you imagine, we speciated and then just started domesticated agriculture from day one of your speciation. That's again rather odd. We're primarily nomadic persistence hunters that evolved in a near equatorial environment, the plains of Ethiopia, Africa. Our invention of domesticating mass amounts of edible plants came
much later.... as in hundreds of thousands of years later. If we weren't "equipped" for hunting and gathering, we would not be having this conversation now, friend. In fact, we've been hunter gatherer tribesmen far longer than we've been farmers.
That's one. Two, Jungle environments are in simplified terms just flatly closer to our evolutionary common ancestors' environments than the environments and challenges seen in northern climates. And yet again even just ignoring the biomass availability in jungle or similar tropic and near-tropic environments as compared to winter in northern climates, its simply more congruent of an environment with how we, the great apes, and our common ancestors evolved.
Three may be your most ignorant point, but likely just your most dishonest given the level of stupidity it would require for you to make it. That is, populations driven or pulled from Africa did NOT evolve in northern climates. (Apologies if I'm misreading that). That's so absurd you could falsify that claim by looking at the epidermis level phenotypic differences between people of European and African descent. I'm sorry, but if that's the "controversy" then you're being a rather dishonest piece of shit.
As for the cognitive differences, yes, the challenges that winters offer in northern climates are responsible for the stratified differences we see in different human populations. Without winters, and the perineal growth seasons of wild and domesticated biomass that other climates offer, the same level of deferred gratification is NOT required. To flesh that out for the honestly curious, if you have to plan in advance a portion of your surplus that's going to get you through ten months where nothing is growing and everything else you're hunting is going into starvation mode itself, then that takes some significant cognitive foresight. An amount of foresight and an evolutionary pressure, other populations of humans did not have.
That explanation is buttressed by any number of different cognitive metrics from IQ to deferred gratification that show differences between human populations. People of African descent or descendance from near tropical climates reliably demonstrate lower deferred gratification than people of European or East Asian descent in studies like the "marshmallow test". And, perhaps the most recorded differences are the mean IQ differences between and among populations that also improve that explanation.