A growing number of scientists and other professional researchers are amassing evidence that, in all kinds of creatures, an innate impulse and ability to play - goof off a little, be curious, or just have what looks to even the most jaundiced human gatherer of data like having some aimless and enjoyable fun - has been favored by evolution down through the eons.
MORE: http://abcnews.go.com/Technology/story?id=15516556
See also...
Improbable evolution: how life beats the odds
http://www.smartplanet.com/blog/savvy-scientist/improbable-evolution-how-life-beats-the-odds/291?roto-fd-feature=;tag=content
Did Early Humans Ride the Waves to Australia?
http://online.wsj.com/article/SB10001424052970204740904577192960294508268.html
