It is well documented that human brains have increased in size over the course of our evolutionary history. Less appreciated is the fact that human brains have decreased in size since the Pleistocene. When exactly these changes happened, or why, was not well known.
“A surprising fact about humans today is that our brains are smaller compared to the brains of our Pleistocene ancestors. Why our brains have reduced in size has been a big mystery for anthropologists,” explained co-author Dr Jeremy DeSilva, from Dartmouth College.
To disentangle this mystery, a team of researchers from different academic fields set out to study the historical patterns of human brain evolution.
Brains use up a lot of energy, and smaller brains use less energy. The externalization of knowledge in human societies, thus needing less energy to store a lot of information as individuals, may have favored a decrease in brain size.
“We propose that this decrease was due to increased reliance on collective intelligence, the idea that a group of people is smarter than the smartest person in the group, often called the ‘wisdom of the crowds’”, added [co-author James] Traniello.
