More Yawning Chimps

Such a good yawn! Another example of contagious yawning in chimps from Campbell & de Waal (2011) - Chimpanzee Contagious Yawning.

 Other related posts:
Empathetic Chimp - 26-06-2011 
A Joke About Evolutionary Psychology - 29-05-2011 
Laughing Chimpanzees - 25-05-2011 
Go Bonobos! - 24-05-2011