Intelligence is no human sideshow but an evolutionary main event. The power to foresee, to call upon the past in terms of the future, to evaluate, to imagine solutions, is a power flowing from old time springs. The human mind may be denied the policeman's privilege of arresting this instinct or that. It may sit as no more than a moderator in the eternal instinctual debate. But it is a moderator with unlimited investigative powers.

African Genesis: A Personal Investigation into the Animal Origins and Nature of Man (1961)