Human intelligence developed to an extreme level that is not necessarily adaptive in an evolutionary sense. Firstly, larger-headed babies are more difficult to give birth and large brains are costly in terms of nutrient and oxygen need [5]. Secondly, cleverer people apparently do not survive or reproduce better. Thus the direct adaptive benefit of human intelligence is questionable at least in modern societies, while it is impossible to study in prehistoric societies. However, alleles coding for even larger human brains are spreading continuously even in modern societies [6] [7] This suggests that cleverer humans may gain indirect selective benefits.