Imagine you’re playing a game where you’re trying to find a treat under one of three cups. Sometimes you see where it goes, and sometimes you don’t. If you have no idea where the treat is, you might ask for help — and if your friend is feeling generous, they’ll point you in the right direction.
Now imagine your friend is a bonobo. Turns out, that doesn’t change things much.
A groundbreaking study published today in Proceedings of the National Academy of Sciences suggests that apes, like humans, recognize when others lack knowledge and will communicate to help fill the gap.
Humans are not that unique
For centuries, we’ve thought we were unique amongst the animals on Earth. But the more researchers study other species, the more we realize that we’re probably not as special as we once thought. For instance, one ability once thought distinctly human was recognizing when someone else lacks information.
A new study challenges that. Luke Townrow, a PhD candidate at Johns Hopkins University, wanted to investigate whether bonobos are able to recognize when a collaborative partner does and does not know something. In other words, whether they have a theory of mind.
“Work over the last several decades has illuminated some of the incredible cognitive abilities that nonhuman primates possess, especially when it comes to theory of mind. More and more research has been contributing to our overall understanding of nonhuman primate theory of mind with many studies reporting impressive cognitive feats,” Townrow explained in an email.
The theory of mind is the ability to understand that others have thoughts, beliefs, knowledge, and perspectives that are different from our own. It allows us to predict behaviors, communicate effectively, and engage in complex social interactions. This cognitive skill is essential for cooperation, teaching, deception, and empathy — key traits that shape human societies. Without theory of mind, we wouldn’t be able to recognize when someone is confused, offer help, or anticipate how others might react in different situations.
This capacity is often cited as one of the defining features of human intelligence. The new findings suggest it may have evolved millions of years ago in a common ancestor we share with great apes.
Testing bonobos
To test how well bonobos track another’s knowledge — or lack thereof — Luke Townrow and co-author Chris Krupenye, designed a simple yet effective experiment. They worked with three bonobos, Nyota (25), Kanzi (43), and Teco (13), living at Ape Initiative, a research and education nonprofit.
Once the treat was hidden, Townrow always followed the same script: he removed the barrier, looked at the cups, and said, “Where’s the grape?” He then waited 10 seconds before making a choice.
“To try and minimize the risk that the bonobos were simply responding to my behavioral cues rather than considering my ignorance, we made sure that both knowledge and ignorant experimental trials had the same choreography, especially during the response window. The only difference between the two conditions was whether I had seen the food being hidden or not. “
The key question: Would the bonobos behave differently depending on whether Townrow had seen the hiding process?
The answer was clear. When Townrow already knew where the treat was, the apes typically stayed still. They knew he’d get the treat. But when he had been blind to the hiding, they acted fast — pointing eagerly to the correct cup, sometimes quite emphatically.
“We predicted that if apes are really tracking ignorance, when their partners lacked knowledge they would be pointing more often and more quickly and that’s exactly what they did,” Krupenye said. “The results also suggest apes can simultaneously hold two conflicting world views in their mind. They know exactly where the food is, and at the same time, they know that their partner’s view of the same situation is missing that information.”
Not all bonobos are the same, but they all have a theory of mind
The findings build on previous research showing that chimpanzees in the wild will vocalize to warn group members who are unaware of potential dangers This study takes that idea further by replicating a similar behavior in a controlled environment and using a different form of communication — pointing rather than vocalization.
“There is one piece of work from the wild that is incredibly creative and elegant that found chimpanzees will vocalize to warn group-mates who are ignorant to potential threats like snakes. We wanted to conduct an experiment that compliments and extends this one under highly controlled conditions and measure a different modality of communication (pointing).”
Kanzi, in particular, seemed to be more persistent in pointing to the treat. This is possibly owed to different personality traits
“It did appear there were differences between individuals regarding how often they pointed to communicate across both experimental conditions. However, it is important to remember that all three of the bonobos showed the same trend in their responses — pointing more often and more quickly when the experimenter did not know where the food was hidden, compared to when he did.”
Going forward, Krupenye and Townrow plan to explore the motivations behind apes’ communication. Do they point simply to get a reward, or do they recognize that communication can shape another being’s understanding of the world?
As research continues, one thing is clear: the gap between human and ape intelligence is smaller than we once believed.
The study has been published in the Proceedings of the National Academy of Sciences
