At eighteen, the human brain processes information faster than it ever will again. At sixty-seven, the same brain has acquired a vocabulary that will not begin to decline for another decade. The peer-

The standard scientific view, for most of the twentieth century, was that human intelligence peaked in late adolescence or early adulthood and then began a long, gradual decline. The intuition behind the view was that the brain, like the rest of the body, reached its biological peak in the years immediately following maturation and that […]