Image: Mathias Appel/Flickr

Sizing up competitors can often be a bit of a gamble for many species, but lemurs can instantly sniff out weakness in their counterparts.

A decade-long research project at Duke University recently revealed that the endangered primates native to Madagascar can identify each other’s weaknesses just by the scent they leave behind. That’s bad news for injured or weaker individuals hoping to blend in unnoticed, as males appeared to respond more aggressively to scents that smell “off.”

Lemurs communicate by excreting a strong-smelling substance from their genitals onto trees in their territory to alert others to their presence, their health status and whether they are available for mating. The researchers collected samples of these secretions from ring-tailed lemurs at Duke Lemur Center in Durham, North Carolina over a span of 10 years.

Image: Keven Law/Flickr

The results showed that injured animals had a significant decrease in the number of compounds in their scent — a drop of nearly 10%.

“Our study shows that physical injury from peers dampens an animal’s scent signature, and in a way that its counterparts can detect,” said Duke professor and co-author of the study, Christine Drea in a statement.

This is especially problematic for weakened males that are attempting to appear normal during the mating season, when scuffles between males are very common. Even if males appeared outwardly normal, their scents could give them away to others, making them more vulnerable.

Researchers noted that males acted more aggressively towards the males that they sensed were injured, perhaps using the other’s handicap as a way to elevate their status. Healthy males would also show dominance by marking over their injured counterparts’ secretions

“These animals constantly monitor the physical condition of their competitors and respond quickly to any opportunity to climb the social ladder,” said Duke postdoc Rachel Harris.

There’s no hiding weakness in lemur society.

(Featured photo by Noel Reynolds)