In less time than it takes to read and process the information on a hastily scrawled name tag, Belding's ground squirrels can sort out sister from second cousin from total stranger with just a twitch of the nose. In fact, studies of several animal species--including humans--have suggested that kin recognition by smell is not uncommon. Belding's ground squirrels, however, seem especially adept in that regard and use the information obtained to make life or death decisions.

"It's as if these squirrels are reading DNA fingerprints and drawing the family tree with their noses," comments Cornell University psychologist Jill M. Mateo, who has studied the social creatures in the California mountains for five years. A report describing her findings will appear in the April 7 issue of Proceedings: Biological Sciences, a journal of the Royal Society. Mateo predicted that whereas the squirrels should quickly recognize the smell of close kin, they would spend more time sniffing unfamiliar odor compounds from distantly related or unrelated squirrels. Experimental results bore that out.

"The sensitivity and discrimination of their olfactory apparatus is astounding," Mateo remarks. "They're like furry gas chromatography machines." Scent discrimination helps the squirrels decide who to cooperate with in defending territories, or who to protect from predators, Mateo proposes. It may also help them to avoid inbreeding.