Wild African elephants may address each other using individualized calls that resemble the personal names used by humans, a new study suggests.
While dolphins are known to call one another by mimicking the signature whistle of the dolphin they want to address, and parrots have been found to address each other in a similar way, African elephants in Kenya may go a step further in identifying one another.
These elephants learn, recognize and use individualized name-like calls to address others of their kind, seemingly without using imitation, according to the study published Monday in the journal Nature Ecology and Evolution.
The most common type of elephant call is a rumble, of which there are three sub-categories. So-called contact rumbles are used to call another elephant that is far away or out of sight. Greeting rumbles are used when another elephant is within touching distance. Caregiver rumbles are used by an adolescent or adult female toward a calf she is caring for, according to the study.
The researchers looked at these three types of rumbles, using a machine-learning model to analyze recordings of 469 calls made by wild groups of females and calves in Amboseli National Park and Samburu and Buffalo Springs National Reserves between 1986 and 2022. All the elephants could be individually identified by the shape of their ears, as they had been monitored continuously for decades, according to the study.
The idea was that “if the calls contained something like a name, then you should be able to figure out who the call was addressed to just from the acoustic features of the call itself,” said lead study author Mickey Pardo, an animal behaviorist and postdoctoral fellow at Cornell University in New York, who conducted the research while at Colorado State University.
The researchers found that the acoustic structure of calls varied depending on who the target of the call was.
The machine-learning model correctly identified the recipient of 27.5% of calls analyzed, “which may not sound like that much, but it was significantly more than what the model would have been able to do if we had just fed it random data,” Pardo told CNN.
“So that suggests that there’s something in the calls that’s allowing the model to identify who the intended receiver of the call was,” he added.
Call and response
The researchers also found that the elephants probably weren’t just mimicking the voice of the individual they were addressing. By comparing pairs of calls between callers and receivers, as well as the receivers’ calls to other individuals, they discovered that the majority of the calls made by the caller did not sound more like the receiver’s call than when they addressed other individuals, according to the study.
The researchers then played back calls to 17 elephants to see whether they recognized and responded to ones that had originally been directed at them.
They found that the elephants would respond more strongly to a call that was originally addressed to them than to one from the same caller that was originally addressed to someone else. “So that meant that the elephants could tell if a call was meant for them just by hearing that call,” Pardo said.
He added that the study “tells us something about the cognitive abilities of elephants because if elephants are addressing one another in this way, they’re basically coming up with names for each other. That implies some capacity for abstract thought — they have to be able to learn this arbitrary sound and associate it with other individuals and essentially call each other by name.”
Coen Elemans, a professor of bioacoustics at the University of Southern Denmark who was not involved with the study, called the findings “very exciting because the use of names was unknown amongst animals.”
“In some animals, such a parrots and dolphins, individuals can have a specific call that others try to mimic, but that is not equivalent to a human name,” Elemans said.
The evolution of language
Elephants maintain lifelong varied social bonds with many individuals and are often separated from their closely bonded social partners, according to the study.
So, some calls can be used to grab the attention of an individual who is far away, whereas close-distance calls might be used to strengthen social bonds, similar to when humans respond more positively and cooperatively when someone remembers their name, the researchers said.
When elephants were close together, caregiving rumbles were more likely to be correctly classified by the machine-learning model than greeting rumbles. The researchers suggested that caregivers may use names more frequently with their calves to either comfort the calf or to help it learn its name.
Calls by adult females were also classified more correctly than calls by juveniles, suggesting that adult females may use names more in their calls because the behavior takes years to develop, according to the study.
Pardo said most mammals are not really capable of learning to produce new sounds — an ability needed in order to label something with a name.
He added that since humans, dolphins and elephants address individuals in their species with something like a name, “the need to name other individuals may have had something to do with the evolution of language.”
“Maybe this pressure of having all these complex social relationships — and you need to be able to address others as individuals — is what led animals, including potentially our own ancestors, to develop this ability to associate new sounds with new things. That sort of could be what led to language,” Pardo continued.
“It would be super interest to investigate if these names are learned. Only very few animal groups are able to imitate sounds, what we call vocal learning,” Elemans said in an email. “We knew some individual elephants could also mimic sounds. Now this study may point towards why vocal learning may also be important; name calling in the wonderfully complex social biology of elephants.”
The study authors were not able to conclusively determine whether different elephants used the same name to refer to the same individual, or if they addressed the same individual with different names.
They also could not determine which aspects of the calls were the name, with calls also having information such as the identity, age, sex and emotional state of the caller encoded in their characteristics, according to the study.
Pardo said he would really like to figure out “how these calls actually contain a name, and I’d be able to isolate the names for specific individuals, and then I think that would open up a lot of other areas of inquiry.”
