Evolution. Here's the best supporting evidence yet, "Sexually Frustrated Chimp Takes Up Smoking":

BEIJING (Reuters) - Sexual frustration has turned a Chinese chimpanzee from a mild-mannered simian into a problem primate who smokes cigarettes and spits at visitors, the Xinhua news agency says.

Feili, a female chimp in the city of Zhengzhou in the central province of Henan, picked up her nasty habits by imitating visitors who behaved "improperly" around her, Xinhua quoted zoo director Liu Bing as saying on Sunday.

But, Liu said, the root cause of Feili's transformation from a "gentle girl" into a "shrew" lay with the inability to find her a satisfactory mate.

A male chimpanzee at the zoo has failed to live up to Feili's sexual demands, and she has snubbed other potential suitors.

Zoo officials said Feili was not addicted to nicotine, but the chimp has also demonstrated clever -- if not desperate -- behavior to score a smoke.

"The chimp is spitting at tourists and smoking," Xinhua quoted a boy visiting the zoo. "Just now a tourist threw a cigarette butt to just outside the cage, she tried to get the butt with a stick."

Oh man. If anyone knows of any video footage or pictures of this anywhere, please oh please let me know. That definitely would trump a monkey washing a cat.