A primate's fragrance speaks volumes.

• Position: Biology

Perhaps judging a man by his cologne is not as superficial as it seems. Researchers at Duke University, Durham, N.C., using sophisticated machinery to analyze hundreds of chemical components in a ring-tailed lemur's distinctive scent, have found that individual males not only are advertising their fitness for fatherhood, but a bit about their family tree as well.

"We now know that there's information about genetic quality and relatedness in scent," says Christine Drea, associate professor of biological anthropology and biology. The male's scent can reflect his mixture of genes, and to which animals he's most closely related. "It's an honest indicator of individual quality that both sexes can recognize."

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Lemurs, distant primate cousins of humans who split from the family tree before monkeys and apes parted ways, have a complex and elaborate scent language that, until recently, remained undiscovered by humans. Drea indicates it is a language that undoubtedly is richer than we can imagine. "All lemurs make use of scent. The diversity of glands is just amazing."

Ringtailed males have scent glands on their genitals, shoulders, and wrists, each of which produces different smells. Other lemur species also have glands on their head, chest, and hands. Add to these scents the signals that can be conveyed in feces and urine, and there is a lot of silent, cryptic communication going on in lemur society. Wearing a scent-based nametag declaring one's genetics probably is useful in avoiding aggression with closely related males. It also is quite likely to help prevent inbreeding by signaling family relationships to females.

The males have a gland and...