While you might be able to tell if somebody else is injured merely by looking at them, it appears as though lemurs use an entirely different approach: the sense of smell.

Image Credit: David Haring/Duke University

Ring-tailed lemurs rub scent secretions on trees for territorial purposes, and citing a study published in the journal Scientific Reports this week by researchers from Duke University, the animal’s physical condition impacts the content of the scent secretion.

Specifically, injured lemurs secret different chemical balances than healthy ones, and healthy lemurs can discern these differences when they catch a whiff of another’s scent secretions.

The researchers reached their conclusion after swabbing the secretions of 23 injured lemurs between 2007 and 2016, each of which faced different circumstances. Gas chromatography-mass spectrometry (GS-MS) tests soon followed and highlighted the compositional differences.

"Our study shows that physical injury from peers dampens an animal's scent signature, and in a way that its counterparts can detect," said Professor Christine Drea, a co-author of the study.

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The findings highlight implications for injured lemurs during mating season, when males often compete for mates.

These competitions often lead to fights, which can leave individual(s) injured. The result is that a male lemur is left with a less-pungent scent secretion, and this impacts the male’s success with finding suitable mates or competing with other males.

In some cases, dominant lemurs rubbed their scent secretions over the injured lemurs’ secretions simply because they would overpower the latter.

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

"These animals constantly monitor the physical condition of their competitors and respond quickly to any opportunity to climb the social ladder," added Rachel Harris, another author of the study.

Like bullies, dominant male lemurs seem to go after the weakest link to obtain the upper hand. But instead of looking for weakness as humans would, they smell it instead.

Source: Duke University