Elephants are remarkably perceptive when it comes to recognizing specific ethnic groups of people that vary in the degree of danger they are likely to pose, reveals a new study published online on October 18th by Current Biology, a Cell Press publication.
Elephants in Kenya reacted with greater fear when they detected the scent of garments previously worn by Maasai warriors than by Kamba men, the researchers reported. Maasai warriors are known to demonstrate their virility by spearing elephants, while the Kamba agriculturalists today pose little threat, they explained. The elephants also respond aggressively to red clothing, which is traditionally worn by young Maasai men.
On the basis of earlier anecdotal evidence of elephants' behavior toward Maasai people and their cattle, "We expected that elephants might be able to distinguish among different human groups according to the level of risk that each presents to them, and we were not disappointed," said Richard Byrne of the University of St. Andrews.
"In fact, we think that this is the first time that it has been experimentally shown that any animal can categorize a single species of potential predator into subclasses based on such subtle cues," added Lucy Bates, also at the University of St. Andrews.
In the current study, working with the long-running Amboseli Elephant Research Project, the researchers first presented elephants with clean, red clothing and with red clothing that had been worn for five days by either a Maasai or a Kamba man. In comparison to either a Kamba-worn or unworn garment, Maasai-scented clothing motivated elephants to travel significantly faster in the first minute after they began to move, the researchers found. The elephants also traveled farther from the cloth smelling of the Maasai in the first five minutes, and took significantly longer to relax after they stopped running away.
They then investigated whether elephants can also use garment color as a cue to classify humans in the absence of scent differences by comparing their reactions to red versus white cloth. The elephants reacted with more aggression toward red than white, they found, noting that to elephants, red is actually a drab color.
Bates speculated that the difference in the elephants' emotional reaction to odor versus color might relate to the amount of risk they sense in the two situations, adding that elephants have a keen sense of smell. "With any scent present, fear and escape reactions seem to dominate anything else," she said.
Elephants' tendency to flee at the mere whiff of a person may have other implications, Byrne said. "While elephants can undoubtedly be dangerous when they come into conflict with humans, our data shows that, given the opportunity, they would far rather run away, even before they encounter the humans in person.
"We see this experiment as just a start to investigating precisely how elephants see the world but it may be that their abilities will turn out to equal or exceed those of our closer relatives, the monkeys and apes," he added.
The researchers include Lucy A. Bates of University of St. Andrews in St. Andrews; Katito Sayialel, Norah Njiraini, Cynthia J. Moss, and Joyce H. Poole of Amboseli Trust for Elephants in Nairobi; and Richard W. Byrne of St. Andrews in St. Andrews.
This work was supported by a project grant from The Leverhulme Trust (F/00 268/W).
Reference: Bates et al.: "Elephants Classify Human Ethnic Groups by Odor and Garment Color." Publishing in Current Biology 17, 1 C5, November 20, 2007. DOI 10.1016/j.cub.2007.09.060
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