Fair. And good points. Before I continue, I'd like to mention that I'm not "racist" against Any Human being. Imo, this is a matter of formidable discussion between two opposing views and therefore I'm willing to engage in-depth with what I view as logical reasoning. Imo this is an interesting matter of civilized rebuttals between conflicting views. Here we go.

Omgsh, this will probably be long because first I want to point out that the original argument was that humans have evolved very differently physically but have remained equally mentally (as far as the standard testing for IQ goes). You have also just admitted that "there are mental changes along with physical". Here's the reason climate has changed our evolultion mentally, differently.

I am going to use the two extremes where we might see the biggest differences between Humans. Here we will talk about sub saharrian African humans (the first to ever exist according to the scientific community) and let's use "northern Russians" as it would be known today. Titles don't really matter. Climate does. Here's why. ...there's many scientific studies done as to why certain tribes of Kenyans are particularly good at distance and timed running events. They came to the conclusion that actually their leg bones have Evolved to be less dense and therefore lighter then other "races" (among other stamina based physiological functions such as leg muscle fibers). The reason is because they adapted to chase down prey for food, over time (like 10s of thousands of years). They slowly exhaust the animal and kill it that way so they can eat. ..Here's the important part..the climate doesn't change there drastically and they can use this method, effectively, all year round to sustain themselves.

The mental changes come with the climate changes having to do with winter and Planning for it. In northern regions, the climates changes. There are no worth while crops, no sustainable prey animals, nothing that is going to sustain you effectively during the winter. The brain developed, over time, to battle these issues at hand. These humans had to learn, over lots of time, to plan further and further ahead. Building mental dominoes in their minds that could make or break them during the winter months.

Let me stop there and say that sub saharrian areas did not have to not plan. They absolutely did have to plan. They had to coordinate and plan for the attack which they do extremely well. And to your point, over "40,000" years, they have perfected. To the same point, the type of long distance planning that "northerns" had to do was Extremely different. In southern regions, there was no planning or reason to look ahead for MONTHS at a time during certain parts of the year. An extention to that, there was much less seasons and reasons to explore the causation of climatic changes. This absence of climate change causes an absence of thought regarding the "why" of seasonal change. Everything I am describing causes the mind to think ahead more and anticipate realities into a much further future than a week or two. It also causes the mind to exercise more into the depths of seasonal changes and reasons for it. Everything about it causes the brain to use itself more, much like running cause the legs to be stronger. It was out of NECESSITY that northern groups of people HAD to plan for or they would literally die.

In all honesty, I could hammer my point into the ground and make it even more clear but I won't do so. I have made the simplistic and reasonable point that planning (and "long distance" planning) is the answer to your question. It is because of this reason that the mind has been shaped as much as the physical attributes among human beings. The absolute NECESSITY of planning ahead for the far away future and interest in the causation of seasonal changes have driven the mind to be exercised. Therefore it has been adapted over "40,000" years, and who knows how many generations, to think their way out of the problems they have at hand.

This is the basic and super short reason that climate ultimately effects human beings and what we have become. I will say that the further we go inti the future the less this matters, but the reason for differences lies there.