The mere whiff of a Maasai man's clothing is enough to strike fear in African elephants and send them thundering to the safety of tall grasses, according to a new study.

Maasai men have been known to occasionally spear elephants, perhaps as a ritual to show virility.

Clothing worn by less threatening Kamba men, however, evokes a milder reaction.

"They think about people in the way you and I think about people," said study co-author Richard Byrne, a psychologist at the University of St. Andrews in the U.K.

"There are different types [of people] and they have different characteristic behaviors and—if I was an elephant—very different implications, some of them being the type who occasionally spear you."

Elephants, he added, categorize each group of people differently.

The finding suggests that elephants have learned to perceive the degree of danger various ethnic groups pose to their well-being, Byrne and colleagues at St. Andrews and the Kenya-based Amboseli Trust for Elephants conclude in the current issue of the journal Current Biology.

Red Cloths

The Maasai are pastoralists—they herd cattle and thus may pick up cattle odors, Byrne noted. In addition, they wear body decorations of ochre and sheep fat that have a distinctive smell.

The Maasai diet is also based around milk and cattle, which Byrne said produces a different body odor than that of Kamba men, who rely on agriculture and eat a more Western diet of meat and vegetables.

The researchers exposed elephants in the field to a red garment worn by a Maasai, a Kamba, or no one at all and studied the reaction.

The elephants had never encountered the men who had worn the scented clothes, Byrne noted. And the clothes were kept out of sight, so smell was the only way for the elephants to detect them.

Both the Maasai and Kamba scents caused the elephants to pick up their trunks and point them towards the clothes to investigate. The animals also bunched together, a behavior that signals concern, Byrne said.

Once the elephants picked up on the nature of the scents, however, the reactions differed.

The elephants typically walked about 150 feet (46 meters) away from the Kamba scent, relaxed within a few minutes, and continued grazing.

"In the case of the Maasai scent, they would head off directly downwind, sometimes almost running, and often wouldn't stop for a kilometer [0.6 mile]," Byrne said.

"Even when they did stop, they were still bunched together, sniffing the air, and took several minutes even when they were a kilometer away to relax enough to start feeding. So it was a very strong effect."

In a second experiment the researchers exposed the elephants to a white cloth typical of garments worn by Kamba men and a red cloth like those often worn by Maasai. Neither garment had been worn.

Byrne noted that if the elephants were simply reacting to conspicuousness, the stronger reaction would have been to the bright white. But the stronger reaction was toward the red, which for elephants is a drab color.

"It was almost as if the fact that there wasn't a Maasai there—otherwise they could have smelt him—allowed them to express their real feelings, which was not very polite. They didn't like them," he said.

The researchers also expected the elephants' personal histories to evoke different individual reactions. Some have a family member that was injured or killed by spearing, for example. But they all reacted similarly.

"So we think the fear was probably socially transmitted among the elephants," Byrne said.