TKTL1

Since NYT and the original paper are paywalled, let us all thank the Turtle for Anneline Pinson's "Human TKTL1 implies greater neurogenesis in frontal neocortex of modern humans than Neanderthals". So let's think of a reason why we got TKTL1 and the Neanders didn't.

I would guess at abstract thought over memory. Neanders would have to own good memory simply to survive a Pleistocene winter. On the other hand, once they learn (or physically evolve) how to survive in (say) a Pyrenees valley, a Neander tribe has little incentive to innovate. Innovation takes time away from hunting and gathering.

Modern East African TKTL1 perhaps arose where the enemy wasn't "General Winter", a vicious enemy but a predictable one; but where the enemy was other humans and also cunning beasts like the jackal, the lion, and the baboon.

I'm somewhat reminded of the Germans at the point the Romans first met 'em. The Romans thought the Germans were a pack of dolts. I mean, yeah; racists lol look at what they thought of West Africans. But the Romans didn't think that the Iranians or (especially) the Greeks were dummies.

Another question we might ponder is whether the TKTL1 mutation had evolved in such modern-humans as expanded into Eurasia and then simply failed to take hold. It seems untraceable in the hybrids as of 2020 excavated. If I'm right then Eurasian conditions selected against this, so their absence in the hybrids doesn't prove much.