Researchers from Johns Hopkins University studying bonobos found that they would point to where treats were hidden if they could see their human partner didn’t know where they were, according to a statement from the university, published Monday.
Working with three male bonobos, study co-author Luke Townrow, a Johns Hopkins PhD student, would sit across a table from one of the animals as another person placed a treat under one of three cups.
In some cases, Townrow would be allowed to see which cup the treat was under, and the bonobo would wait for him to pass it the food.
At other times, he would not be able to see where the treat was, and the bonobo would point to the right cup to help him find the food.
The “seemingly simple experiment that demonstrated for the first time that apes will communicate unknown information in the name of teamwork,” the statement reads.
And study co-author Chris Krupenye, a Johns Hopkins assistant professor of psychological and brain sciences, told CNN that the study “is one of the clearest pieces of evidence that a non-human primate understands when someone else is ignorant.”
This ability to intuit gaps in others’ knowledge is known as the theory of mind.
“As humans, we have theory of mind, the ability to think about others’ perspectives,” Krupenye told CNN on Tuesday.
“It’s a crucial feature of human psychology,” he added, explaining that it allows us to cooperate and teach people things that we understand they do not know.
Theory of mind has previously been considered unique to humans, but the study shows that bonobos share this capability.
“The evidence we have is a good indication that they do have a theory of mind,” said Krupenye, explaining that the study builds on previous research into the theory of mind in chimpanzees.
Next, the team plans to explore the bonobos’ motivations for sharing information and the way that they think about other individuals’ minds.
“What we’ve shown here is that apes will communicate with a partner to change their behavior,” Townrow said in the statement, “but a key open question for further research is whether apes are also pointing to change their partner’s mental state or their beliefs.”
Krupenye told CNN that he hopes the study will help to raise awareness around bonobos, an endangered species found exclusively in the Democratic Republic of Congo.
“This kind of work shows us how rich their social lives are,” he said.
Alexander Piel, a biological anthropologist at University College London, who was not involved in the research, told CNN that the study is informative and “provides compelling evidence that these 3 individuals adjust their behavior based on the knowledge state of a human.”
However, he highlighted the fact that the study involved only three bonobos, who live in captivity and were communicating with a human, which would not be common in the wild.
Nonetheless, Piel said that “those issues do not in any way cast doubt on the importance of the study.”
“The results offer another glimpse into the minds of our closest relatives, an increasingly mirror-like reflection of our cognitive faculties,” Piel told CNN on Wednesday.
The study is published in the journal Proceedings of the National Academy of Sciences.
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