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In order to receive treats, apes enthusiastically indicated their locations to humans who weren’t aware of where the treats were hidden. This seemingly straightforward experiment for the first time showcased that apes can share unknown information with others for the sake of teamwork. The research also presents the most convincing evidence yet that apes are capable of recognizing another individual’s lack of knowledge, a skill previously thought to be exclusive to humans.
The research conducted by the Social and Cognitive Origins Group at Johns Hopkins University has been published today in Proceedings of the National Academy of Sciences.
“Understanding when someone lacks knowledge is crucial for complex social behaviors. It’s fundamental to our cooperation, communication, and strategic collaboration,” said Chris Krupenye, a co-author and assistant professor of psychological and brain sciences at Johns Hopkins, who studies animal cognition. “Due to the theory of mind being linked to unique human capabilities like teaching and language, many assume it is absent in animals. However, this study highlights the rich cognitive similarities shared by humans and other apes, indicating that these abilities may have evolved millions of years ago with our common ancestors.”
Krupenye and co-author Luke Townrow, a PhD student at Johns Hopkins, conducted their research with three male bonobos named Nyota, 25, Kanzi, 43, and Teco, 13, all housed at Ape Initiative, a nonprofit focused on research and education. During the testing, one bonobo would sit across a table from Townrow. The bonobo observed as another individual placed a treat, either a grape or a Cheerio, under one of three cups. At times, Townrow could see where the treat was hidden, and other times he could not. If Townrow located the treat, the bonobo could have it.
Regardless of whether Townrow had seen where the treat was placed, he would ask, “Where’s the grape?” and wait for 10 seconds. If he had witnessed the treat being hidden, the bonobo would typically remain still during this pause. However, if Townrow had not seen where the treat was, the bonobo would promptly point to the correct cup—sometimes quite animatedly.
“Their fingers would point right through the mesh—it was evident what they were communicating,” noted Krupenye. “One bonobo, Kanzi, who was very food-driven, would frequently point during certain parts of the experiment—he’d tap several times to grab our attention and was quite persistent.”
This study is the first to replicate similar findings in a controlled setting, reflecting observations from the wild which suggest that chimpanzees will vocalize to alert group members about potential dangers they may not be aware of, such as the presence of a snake.
“We theorized that if apes are genuinely aware of others’ ignorance, they would point more often and more rapidly when their partners were uninformed, and that’s precisely what happened,” Krupenye explained. “The outcomes also indicate that apes can hold two conflicting perspectives in their minds simultaneously. They know where the food is, while also recognizing that their partner lacks this information.”
The team was excited to further validate the cognitive abilities of apes.
“There are ongoing discussions in the field regarding primate abilities, and it’s thrilling for us to confirm that they indeed possess complex cognitive skills that some have previously denied,” said Krupenye.
Moving forward, the team plans to investigate the apes’ motivations and their understanding of the minds of other individuals.
“What we have demonstrated here is that apes will communicate with a partner to influence their behavior,” said Townrow, “but a key question for future research is whether apes are pointing to alter their partner’s mental state or beliefs.”
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