Science Daily: News & Articles in Science, Health, Environment & Technology. Discover Magazine: The latest in science and technology news, blogs and articles - If Modern Humans Are So Smart, Why Are Our Brains Shrinking? A recent study he conducted with a colleague, Drew Bailey, led Geary to this epiphany. The aim of their investigation was to explore how cranial size changed as our species adapted to an increasingly complex social environment between 1.9 million and 10,000 years ago. Since that period predates the first alphabets, the researchers had no written record with which to gauge the social milieu of our predecessors. Consequently, the Missouri team used population density as a proxy for social complexity, reasoning that when more people are concentrated in a geographic region, trade springs up between groups, there is greater division of labor, the gathering of food becomes more efficient, and interactions among individuals become richer and more varied.
Bailey and Geary found population density did indeed track closely with brain size, but in a surprising way. When population numbers were low, as was the case for most of our evolution, the cranium kept getting bigger. John hawks weblog | paleoanthropology, genetics and evolution. Richard Dawkins: Why the universe seems so strange. Juan Enriquez: The next species of human.