By Traci Watson
When humans talk, elephants listen – and listen closely. New research shows African elephants can tell people of different ethnic groups apart after hearing them speak just a few sentences.
The research also found that elephants listening to human utterances can distinguish between men and women and between adult and child. More than just a parlor trick, this keen insight into human language may help elephants decide whether a nearby human is a fearsome predator threat or a minor nuisance.
"They're using vocal information from another species – us – and they're using that to discern threat," says study co-author Graeme Shannon, a behavioral ecologist at Britain's University of Sussex. "That takes really advanced cognitive abilities. … These are subtle differences these elephants are attending to."
Those huge ears aren't for nothing. Elephants can distinguish between the roar of a single lion and the roaring of a trio of lions, and the oldest, most seasoned elephants can tell the roar of a male lion from the roar of a female, according to a 2011 paper by Shannon and his co-author Karen McComb, also of the University of Sussex. Elephants also distinguish between the signature calls of many other elephant groups, including groups they haven't seen for years, McComb has found.
To test elephants' ability to parse human speech, the researchers turned to the 1,500 or so elephants roaming Kenya's Amboseli National Park. A cattle-herding people called the Maasai, who live near the park, once speared Amboseli elephants on a regular basis. Now they attack elephants only occasionally, sometimes to avenge community members killed by elephants, sometimes because of conflicts over water and grazing space. By contrast, the Kamba people, farmers who also live near the park, pose little threat to the animals inside Amboseli.
The scientists placed loudspeakers – disguised with a screen of palm leaves – near herds of elephants, then serenaded the animals with recordings of a person saying, "Look, look over there, a group of elephants is coming." When the voice belonged to a Maasai man, the elephants tended to sniff the air and bunch closely together for protection. But when the voice was a Kamba man's, the elephants were more nonchalant. The elephants also reacted with relative calm to the voices of Maasai women and boys, who, unlike Maasai men, generally don't take part in spearing elephants.
The animals' responses show they're extracting clues about ethnic group, gender and age from human voices to gauge when to react immediately and when to stay put a bit longer, the researchers say. For the ultimate test, the scientists tinkered with the recording of a male Maasai to mimic a woman's speech, including changes to make the man's voice higher. There was no fooling the elephants. They reacted just as they had to unaltered male Maasai voices, suggesting they are picking up gender signals more accurate than those used by humans, the scientists say in this week's Proceedings of the National Academy of Sciences.
The findings are in keeping with an earlier study finding that elephants retreat in fear when they sniff clothing worn by Maasai but not when they take whiffs of clothing worn by Kamba, says an author of that study, Richard Byrne of the University of St. Andrews in Scotland. What's new here, he says, are the data suggesting elephants can distinguish men and women, who pose different levels of risk.
The elephants' abilities are "pretty remarkable," says Joshua Plotnick, a behavioral ecologist at research non-profit Think Elephants International, who was not involved in the new study. The study "is indicating that elephants are learning to adapt to a growing threat in their environment, and the unfortunate and disturbing part is that threat is us. … It just goes to show how intelligent these animals are that they can be this flexible."