The hominin brain grew and developed for over 7 million years, from Sahelanthropus tchadensis to Homo sapiens, about 200,000 years ago. Then the growth and development seems to have stopped. There has been no clear evidence for evolution in Homo brain size since sapiens first left Africa. If Homo sapiens were smarter than Homo erectus and Homo neanderthalensis 200 millennia ago, why are humans no smarter today than those sapiens that first left Africa as the evidence suggests?
