Linking brains and brawn: exercise and the evolution of human neurobiology

So ask your doctor how much exercise you need to improve your cognition. Maybe you need to start running down your meals again, Squirrels and rabbits are pretty fast. I doubt I'd ever be able to chase down a deer. Brocolli does not count.
http://www.ncbi.nlm.nih.gov/pubmed/23173208

Abstract

The hunting and gathering lifestyle adopted by human ancestors around 2 Ma required a large increase in aerobic activity. High levels of physical activity altered the shape of the human body, enabling access to new food resources (e.g. animal protein) in a changing environment. Recent experimental work provides strong evidence that both acute bouts of exercise and long-term exercise training increase the size of brain components and improve cognitive performance in humans and other taxa. However, to date, researchers have not explored the possibility that the increases in aerobic capacity and physical activity that occurred during human evolution directly influenced the human brain. Here, we hypothesize that proximate mechanisms linking physical activity and neurobiology in living species may help to explain changes in brain size and cognitive function during human evolution. We review evidence that selection acting on endurance increased baseline neurotrophin and growth factor signalling (compounds responsible for both brain growth and for metabolic regulation during exercise) in some mammals, which in turn led to increased overall brain growth and development. This hypothesis suggests that a significant portion of human neurobiology evolved due to selection acting on features unrelated to cognitive performance.

A New York Times article about it here:

Exercise and the Ever-Smarter Human Brain