While those living 250k years ago would have looked very very similar to us physically, the evidence suggests we did not become as smart as we are today until about 70k years ago. My understanding is that this claim is based on the fact that the earliest evidence we have of things like art, musical instruments, fish nets, etc. don’t appear in the archeological record until 70k years ago.

My personal theory on this is that humans became significantly more intelligent around 74k years ago as a result of extreme selective pressures due to the cataclysmic eruption of the super volcano known as Mount Toba (in Sumatra I believe). We know for a fact this eruption occurred and that it sent the world into a 1000 year ice-age (think nuclear winter minus the radiation for a decade followed by a thousand years of significant global cooling). During this period the human population fell to only a few thousand or less. That this population bottleneck occurred is a result of the eruption is a fairly well known hypothesis supported by some genetic evidence.

The part of this that I came up with on my own (my personal theory - though I’m probably not the first to connect the dots) is that during this period of genetic bottlenecking only the smartest managed to survive. The extreme environment those people must have lived through would have challenged them far beyond anything they had faced before. Most did not make it. Whole clans/tribes died out in those first years after the eruption. Only the cleverest (and perhaps most cooperative/social) managed to survive and procreate. With a massively reduced population, any genetic variation that could provide additional survival advantages would be selected for, and that selected process would have an exaggerated effect due to the low population numbers.

This theory would help explain why we start seeing archeological evidence of modern human intelligence (again, via art, nets, etc.) around 70k years ago. Perhaps it also explains why we almost seem “too smart” or seemingly smarter than necessary today.