Humans owe our impressive intellect to our large brains, which are unusually sophisticated thanks to evolution. The first surge in our brain size occurred between 2 million and 800,000 years ago, when our species' increase in territory and physical size caused our brains to literally grow. As the climate changed between 800,000 and 200,000 years ago, human brains became even more complex so people could adapt to their new environments. The neocortex in particular expanded during this time, since this region of the brain controls higher-order brain functions including language, motor commands, sensory perception and spatial reasoning.
Yet while these past periods of growth occurred over thousands of years, a recent study in the journal JAMA Neurology reveals that the human brain has in recent years grown considerably on a mere decade-by-decade basis.
