Endurance athletes sometimes say they're "addicted" to exercise. In fact, scientists have shown that rhythmic, continuous exercise — aerobic exercise — can in fact produce narcoticlike chemicals in the body.
Now researchers suggest that those chemicals may have helped turn humans, as well as other animals, into long-distance runners.
The man behind the research is University of Arizona anthropologist David Raichlen, a runner himself. He does about 25 miles a week.
The bake sale, a staple of school fundraising for generations, is getting squeezed. The epidemic of childhood obesity is leading some districts to restrict the kinds of foods sold or to ban the sales altogether, Bloomberg Businessweek's Stephanie Armour explained on Friday's Morning Edition.