Male lemurs may use their fruity-smelling wrists to attract mates

Male ring-tailed lemurs produce a sweet, fruity aroma from glands on their wrists, which seems to attract females during breeding season. The chemicals responsible for the smell may be the first sex pheromones identified in primates.

By rubbing their wrists, male ring-tailed lemurs (Lemur catta) can release chemicals that advertise their social rank or mark out their territories. But it was not known whether they could also produce chemicals to attract females.

Kazushige Touhara at the University of Tokyo, Japan, and his colleagues noticed that the female lemurs in their facility tended to sniff the males for about 2 seconds longer during the breeding season than outside it. To investigate what exactly the females were smelling, they collected secretions from the male lemurs’ wrists and analysed them in the lab.

“Usually sex pheromones utilised in wild animals tend to smell bad,” says Touhara. “We are surprised that the identified odours in this study smell relatively good to humans,” he says. Touhara describes the smell as “fruity and floral”.

Analysis of the secretions revealed three chemicals, called aldehydes, which seem to be responsible for the smell.

To test whether the scents attracted potential mates, the researchers presented two female lemurs with cotton pads dipped either in secretions from two male lemurs, or diluted solutions of each of the three chemicals that make them up. They did this during the breeding season.

The females spent slightly longer sniffing these cotton pads than they did smelling secretions taken from the male lemurs outside the breeding season.

Giving testosterone to one male lemur outside the breeding season induced the production of the same sweet aroma, suggesting testosterone may play a role. Touhara says these chemicals are the first sex pheromone candidates identified in primates, although further studies are needed to confirm whether the chemicals actually lead to increased mating.

“Sniffing and other olfactory behaviours by females should not be interpreted as expressing a preference in relation to male attractiveness,” says Peter Kappeler at the University of Göttingen, Germany. He also says that other factors, such as how familiar the female lemurs were with the males, may have influenced the amount of sniffing observed in the study.

If these are pheromones, they could be useful for increasing the reproductive efficiency of lemurs, which are endangered, says Touhara.