Instead, they are sniffing to analyze secretions from facial scent glands, hoping to learn from the complex odor bouquet who is family and who's not. More remarkably, they are determining in a matter of seconds precisely who is close-enough kin to risk their lives helping -- and perhaps even whether they are too closely related to for mating.
"It's as if these squirrels are reading DNA fingerprints and drawing the family tree with their noses," says Cornell University psychology researcher Jill M. Mateo. Her five years of field studies in the California mountains, as reported in the Proceedings: Biological Sciences (April 7), a journal of The Royal Society, Britain's national academy of science, are the first to show how recognition odors allow precise estimates of kinship, even among distant relatives.
Published as "Kin-recognition abilities and nepotism as a function of sociality" and funded by the National Science Foundation, the study examines potentially risky nepotistic behaviors that are shown to close relatives. It aims to answer the questions: How do social animals, such as Belding's ground squirrels, determine which other animals have a genome so similar to theirs that helping them survive is like perpetuating one's own complement of genes? And how do they know where to draw the line, declining to help more distant relatives because, even though they smell vaguely similar, the genetic benefits of helping do not outweigh the costs of help?
The psychologist is reluctant to extend the squirrel behavioral studies to human affairs. Yet she is mindful of experiments by others, including studies of human odors, which suggest that kin-recognition by smell evolved across a wide variety of animals. So far, Belding's ground squirrels are the champions of kin-sniffing, but many more species remain to be investigated.