Gorillas can tell human voices apart
Apes react differently to people they know and like than people they
don't like, strangers

Date:
October 12, 2021
Source:
University of Georgia
Summary:
A new study is the first to show that gorillas are able to recognize
familiar human voices based on their relationship with the speaker.



FULL STORY ==========================================================================
Many animals recognize the voices of members of their own species, and
some can even recognize those of other species, such as humans. But
it turns out a few animals, such as gorillas, can not only recognize
familiar voices but also connect those voices to pleasant or not so
pleasant memories.


==========================================================================
A new study from the University of Georgia is the first to show that
gorillas are able to recognize familiar human voices based on their relationship with the speaker.

The researchers found that captive gorillas responded negatively when
they heard the voices of people they didn't know or with whom they'd
had negative interactions. Their reaction indicates that the apes likely recognized who the voices belonged to and possibly the nature of their relationship with those individuals.

Although this project focused specifically on gorillas at Zoo Atlanta,
the findings, published in the journal Animal Cognition, have wider implications for the captive animals' wild cousins.

"I worked mostly with wild gorillas, and one downside of working with
wild primates is that through the habituation process we could make them
much more susceptible to hunters because they become used to seeing
and hearing people," said Roberta Salmi, lead author of the study and
director of the Primate Behavioral Ecology Lab in the Franklin College
of Arts and Sciences. "If they are actually able to distinguish between
people, there is hope." Animals can recognize voices A wide variety of
animals appear to be able to recognize and differentiate between voices
of their same species. But some can also do that with other species.



========================================================================== "Babies are able, for example, to recognize the voices of their mothers
and their scent. That's wired into animals," Salmi said. "In the wild, we
know that some monkeys also form specific associations with individuals of other species." It's a survival tactic. If a monkey hears and recognizes
the distress calls of a known individual, they know something is wrong
and can try to hide or escape danger.

But whether undomesticated animals can recognize individual humans is
a bit murkier.

Research has shown that dogs and cats can distinguish between their
owner's voice and the voices of others. They can even detect changes in
tone -- which is the real reason your dog looks so guilty after toppling
the garbage can.

Rover's not actually guilt-stricken. But dogs and cats have been
domesticated for centuries, creating a close bond between people and
their companion animals.

Animals in proximity to people, such as crows, pigeons and even wild
elephants, have also been shown to differentiate between voices that
they were familiar with and those they weren't. These studies suggest
that being able to differentiate voices and assess the threat level may
be important for animals with increased exposure to humans.



========================================================================== Salmi and her team noticed the gorillas responded negatively
to the presence of specific people who came into their indoor
enclosure. Specifically, the animals seemed to grow agitated at the
presence of veterinarians and one maintenance worker. But it was unclear whether the animals were only reacting to visually seeing the people.

Apes may gauge threats by familiarity of human voices Over the course
of about six months, the team played the apes audio recordings of three
groups: long-term keepers who knew and worked with the gorillas for at
least four years and had positive relationships with them; people who the
apes knew and had negative interactions with, including veterinarians and
the maintenance worker; and people who were unfamiliar to the animals. All
the participants said the same phrase, "Good morning. Hello," which is
how keepers typically greet the gorillas.

The apes had minimal reactions to the voices of their keepers. However,
when they heard the voices of people they didn't know or with whom they'd
had negative experiences, the gorillas responded with signs of distress,
such as increased vigilance and vocalizations.

"One of the first things we saw was something that also happens in
the wild: If there's any sound that seems threatening or unfamiliar,
they stopped what they were doing and focused their attention on it,"
Salmi said. "It's something we do too. If it's not a threatening sound,
I keep doing my own business. If I hear that there is someone in my house,
I immediately stop what I'm doing to hear what's going on." For gorillas,
it's the first sign of vigilance. After hearing unfamiliar voices or the
voices of people with whom they'd had negative interactions, the apes in
the study stopped eating their treats or whatever else they were doing
and started looking toward the sound to gauge whether the voices were
a threat. It was unclear whether the gorillas considered the strangers
to be as threatening as the veterinarians and maintenance worker.

"Some primates are able to distinguish and have different reactions
to humans, according to whether they are hunters or researchers,"
Salmi said. "If wild gorillas are able to distinguish between people
who behave differently, not only by sight but also by voice, it would be extremely helpful. It would help me sleep better to know that researchers aren't making the gorillas more vulnerable to hunters." Caroline Jones,
who received her doctorate from the Department of Psychology, and Jodi Carrigan, from Zoo Atlanta, are co-authors of the study.

========================================================================== Story Source: Materials provided by University_of_Georgia. Original
written by Leigh Beeson.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Roberta Salmi, Caroline E. Jones, Jodi Carrigan. Who is
there? Captive
western gorillas distinguish human voices based on familiarity
and nature of previous interactions. Animal Cognition, 2021; DOI:
10.1007/s10071- 021-01543-y ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211012112251.htm

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