Carrying capacities may increase, but so what? You don't see a whole lot of innovation out of Africa. Per capita is what matters, and per capita there is no long-term upwards trend. To quote Clark's Farewell to Alms:

Carrying capacities matter because according to the 10k model, larger populations in novel environment > faster biological evolution.

More people > more brains > bigger economy

And this should accelerate as long as population keeps getting larger.

I was referring to the speed of their adaptation.

Carrying capacities may increase, but so what? You don't see a whole lot of innovation out of Africa.

Don't see why Africa matters here. India and China created plenty of innovation. Higher IQ in the priestly and merchant classes will drive technological, scientific and memetic innovation. It will not be as explosive as the historic development of European civilization, but then again that's pretty anomalous.