Today's NY Times has an article the speculates that exercise was a key element in the development of the human brain and, similarly, that exercise is still a key component in brain health. See: http://well.blogs.nytimes.com/2012/1...me&ref=general

The article ends with:
The broad point of this new notion is that if physical activity helped to mold the structure of our brains, then it most likely remains essential to brain health today, says John D. Polk, an associate professor of anthropology at the University of Illinois at Urbana-Champaign, and co-author, with Dr. Raichlen, of the new article.
And there is scientific support for that idea. Recent studies have shown, he says, that “regular exercise, even walking,” leads to more robust mental abilities, “beginning in childhood and continuing into old age.”
Of course, the hypothesis that jogging after prey helped to drive human brain evolution is just a hypothesis, Dr. Raichlen says, and almost unprovable.
But it is compelling, says Harvard’s Dr. Lieberman, who has worked with the authors of the new article. “I fundamentally agree that there is a deep evolutionary basis for the relationship between a healthy body and a healthy mind,” he says, a relationship that makes the term “jogging your memory” more literal than most of us might have expected and provides a powerful incentive to be active in 2013.