Last week, we learned how elephants have a call that means “HUMAN”, used to alert other elephants to potential danger. This week, scientists reveal that elephants seem to know which humans might pose an actual threat: they can actually distinguish between humans’ age, gender, and ethnicity from just acoustic cues.
Free-ranging elephants often encounter the cattle-herding Maasai people, who are semi-nomadic and sometimes kill elephants over conflicts over water or land for grazing. In a previous study, the scent of red robes worn by a Maasai man provoked a fearful response in elephants.
To further tease this out, a team led by Karen McComb and Graeme Shannon from the University of Sussex recorded Maasai men, women, and boys, along with men of the nearby, crop-farming Kamba people. They all calmly spoke the same phrase in their local language: “Look, look over there, a group of elephants is coming.” Then the researchers played these recordings out of concealed speakers (pictured) in the presence of 47 wild family groups of African elephants (Loxodonta africana) in Amboseli National Park in Kenya.
The elephants, they found, were nearly twice as likely to engage in defensive behavior -- such as bunching into a group around their young or raising their trunks to do some investigative smelling -- during playbacks of Maasai men than they would Kamba men, suggesting that they view the Kamba as non-threatening.
Further, the elephants were more likely to react defensively to playbacks of Maasai men than of Maasai women and boys. This was the case even when the men’s recordings were re-synthesized to match female vocal characteristics. Not fooled.
This is the first evidence of wild animals making fine distinctions in human voices. McComb suspects that the ability to assess threat posed by nearby predators using vocal cues is cultural rather than innate. “Even though spearings by Maasai have declined in recent years, it’s still obvious that fear of them is high,” she tells Nature. “This is likely down to younger elephants following the lead of their matriarchs who remember spearings from long ago.” Families led by matriarchs over the age of 42 never retreated when they heard voices of boys -- but groups led by younger matriarchs retreated 40 percent of the time.
The work was published in Proceedings of the National Academy of Sciences this week.
Image: setup for playback of vocal recordings / Graeme Shannon
Video: elephants’ response to Maasai male playback / Graeme Shannon