Intelligence is the result of runaway sexual selection. The development of the human neocortex began when humanity’s select for males that possessed a rudimentary form intelligence that proved immediately advantageous. As the offspring of females who selected for males with rudimentary intelligence increased relative to the rest of the population, a female innate, physiological female preference developed as a result of the Baldwin Effect. This feedback loop between the development of intelligent offspring and the development of the female preference for intelligent males led to an intelligence arms race between males, where the intelligence that may have existed several generations before is now normative and the new winners in the battle for female attention have to possess a more advanced form of intelligence. Even after male intelligence developed beyond the point where it proved immediately and pragmatically advantageous, the female preference remained thus fueling the runaway development of intelligence.
“So argues Geoffrey Miller. After laying bare the inadequacies of the conventional theories of intelligence, he takes a surprising turn.
‘I suggest that the neocortex is not primarily or exclusively a device for toolmaking, bipedal walking, fireusing, warfare, hunting, gathering, or avoiding savanna predators. None of these postulated functions alone can explain its explosive development in our lineage and not in other closely related species…The neocortex is largely a courtship device to attract and retain sexual mates: Its specific evolutionary function is to stimulate and entertain other people, and to assess the stimulation attempts of others’
The only way, he suggests, that sufficient evolutionary pressure could suddenly and capriciously be sustained in one species to enlarge one organ far beyond its normal size is sexual selection.” (338, The Red Queen)
“Wherever else in the animal kingdom we find greatly exaggerated and enlarged ornaments, we have been able to explain them by runaway, sexy-son, Fisher effect of intense sexual selection..Sexual selection, as we have seen, is very different from natural selection in its effects, for it does not survival problems, it makes them worse. Female choice causes peacocks’ tails to grow longer until they become a burden — then it demands that they grow longer still…And so, having found a force that produces exponential change in ornaments, it seems perverse not to consider it when trying to explain the exponential expansion of the brain.” (339, The Red Queen)
The Red Queen by Matt Ridley