Stink flirting is a thing, just ask a ring-tailed lemur
For human beings, "stink flirting" may not sound like a prudent dating strategy. For ring-tailed lemurs, it is the way to go.
Scientists recently described the results of a comprehensive study of this behaviour — unique in the animal kingdom — that is exhibited by these primates native to Madagascar.
Male ring-tailed lemurs increase their attractiveness to females by secreting from glands on their wrists a fruity and floral aroma smelling similar to a pear, the researchers said.
The behaviour dubbed "stink flirting" involves a male rubbing a fragrant clear liquid that oozes from those glands against his long fluffy tail and then waving the tail at females. The researchers pinpointed three compounds responsible for the scent.
"It turns out that the key odourants were not really stinky," said University of Tokyo biochemistry professor Kazushige Touhara, who led the study published in the journal Current Biology.
"We can say that the identified odours are strong candidates for sex pheromones," Touhara said, referring to chemical substances released by an animal that affects the behaviour of other members of its species.
Until now, no pheromones have been identified in any primates, a group that also includes monkeys, apes and people, Touhara said.
"Although there are many circumstances in which humans utilize olfactory cues for communication, there is no authentic pheromone that has been chemically identified," Touhara said.
"I believe there is no classic sex pheromone in humans that elicits attractive behaviour to the opposite sex. But there are probably crucial odours that affect each other's emotions — for example, a baby's head smell that parents sniff and feel happy, and a woman's axillary (underarm) odours that affect the emotions of males."
Olfactory communication is important for ring-tailed lemurs, which possess well-developed scent glands on their wrists and shoulders that they use to mark territory and designate social rank in addition to romance.
Among primates, lemurs are part of a separate evolutionary lineage with a keener sense of smell than the group that spans monkeys, apes and humans.
The researchers found a close relationship between the male hormone testosterone and the lemur odor compounds. They also found that the male scent worked its magic only during the breeding season when females were sexually receptive, as measured by the amount of time spent sniffing the scent during lab experiments.
Outside of the breeding season, the researchers found, the male gland secretions smelled different — more bitter and leathery. The females, the researchers found, showed scant interest in that.