Ring-tailed lemurs have a peculiar habit of shaking their tails at potential rivals. New research shows that during the breeding season, a male’s trembling tail may instead be whisking sexy odors toward potential mates. The work is still preliminary, but chemical analyses have revealed the odor is a mixture of three chemicals that seem to pique a female’s interest.
The new work “calls attention to the often underappreciated fact” that odors play an important role in primate societies, says Peter Kappeler, a primatologist at the University of Göttingen.
Insects often use behavior-altering odors called pheromones to attract mates. So do mice. But biochemist Kazushige Touhara at the University of Tokyo wanted to know whether primates—including humans—use them as well. Some researchers say yes, but the existence of such “sex attractants” remains controversial.
Ring-tailed lemurs (Lemur catta), named for their fluffy gray and black tails, are unusual among their fellow primates. Males have glands on their wrists that produce chemicals that quickly vaporize when exposed to air—similar to pheromones. They rub their wrists on their tails to transfer the odors before they vaporize, then shake their tails to broadcast the scent.
For most of the year, these lemurs make bitter, leathery smelling chemicals used to keep other males at bay. But during the breeding season, they instead emit a sweet scent, Touhara says. He and his colleagues collected these secretions from the wrist glands with a tiny pipette and analyzed the chemical components.
Three appear important for getting the female’s attention, he and his colleagues report today in Current Biology. All three are aldehydes, which are responsible for lots of odors. The three include one known to be an insect sex pheromone and another that smells like a pear.
Females spend time sniffing or licking the places droplets from these odors settle, but only during the breeding season, and only when all three chemicals are present, the team found. This suggests the identified odors may aid courtship during the breeding season, Touhara says. Moreover, the more testosterone a male had, the stronger the sweet smell, he and his colleagues note.
Most pheromones are single chemicals, says Charles Snowdon, an emeritus psychologist at the University of Wisconsin, Madison, who was not involved with the work. “But what this paper is saying is that it’s a mixture of chemicals that seem to be more important,” he says.
However, Snowdon and Kappeler caution that the study involved very few animals—most of the data come from a single male—and thus the connection to mating is tenuous. Also, female lemurs tend to be quite promiscuous, so it’s not clear that a male needs a sex pheromone to court them. “Sniffing and other olfactory behaviors by females should not be interpreted as expressing a preference” for one male over the other, Kappeler says.
Snowdon also worries many people are too eager to believe in so-called love potions, and may jump to conclusions not only about the existence of sex pheromones in lemurs, but also in people.