Ring-Tailed Lemur
Ring-tailed lemurs such as these at the Duke Lemur Center can tell that a fellow lemur is weak just by the natural scents they leave behind, researchers report. Males act more aggressively toward scents that smell "off." David Haring, Duke Lemur Center

In the game of football or any other sport, a player has to understand his competitor’s strategy and every single move to find his or her weaknesses. The task requires special attention to detail, but when the players in the game are lemurs, it all comes down to sniffing some air.

It may sound a little strange to many, but a group of researchers in the U.S. has discovered that ring-tailed lemurs, endemic to island of Madagascar, emit a foul smell on being hurt – a strange type of natural scent that their counterparts can easily detect to determine the weakness of the other.

Scientists have long known that lemurs’ genitals emit a foul-smelling substance. The animals use this pungent secretion, a mix of nearly 300 different chemicals, as a way to mark twigs and branches and tell other lemurs if they are ready to mate.

However, in order to determine who finally gets the mate or who is in charge, they have to fight. The behavior is very common in the animal group, but at times, these fights – biting, swatting, or pulling – can leave them deeply wounded.

In a bid to understand how these fights and the injuries resulting from them affect scent secretion in the animals, researchers from the University of Duke collected substance samples from 23 different individuals when their injuries were being treated.

They swabbed the samples and conducted a series of tests with gas chromatography-mass spectrometry, which revealed that the signature of their scent had dampened due to the wounds – the number of compounds in the material had declined by as much as 10 percent.

The phenomenon was particularly evident during the mating seasons when lemurs go against each other for a mate. "The breeding season is a period of heightened stress," Christine Drea, the lead author of the study, said in a statement. The scent remained even when the lemurs were in recovery.

More importantly, while it was too subtle to be detected by humans, other lemurs were quick to grab the muted scent. The researchers noted this behavior after conducting a series of behavioral tests in which a group of male lemurs was given a rod dubbed with the scent from their injured and non-injured counterparts.

The findings of the test revealed that the subjects sniffed and marked the scent of injured males much more frequently than in the other case. They gave their attention to the injured odor and marked their dominance over it using extra scent glands on the insides of their wrists.

According to the team, ring-tailed lemurs could be using the scent to determine if their counterpart is capable of fighting or not. If not, they show their dominance by marking over the injured animals' odors. The animals asses the condition of their counterpart from their smell and don't leave any opportunity for the weak to climb the social ladder.

"They respond more competitively when they could easily have the upper hand," Drea concluded.