Did you know that apes react differently to people they know and like than people they don’t like strangers? It’s true. So say the findings of a new scientific study on the topic. This is incredible news because while many animals recognize the voices of members of their own species, only some can recognize those of other species, such as humans. And it turns out only a few animals, such as gorillas, can not only recognize familiar voices but also connect those voices to pleasant or not so pleasant memories*. In short, the new scientific study demonstrated 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…
“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…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.”
*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.
Journal Reference: 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;