Bonobos, our closest primate relatives, showcased remarkable social behavior by participating in a pretend tea party, revealing their capacity for deception.

Kanzi the bonobo (Pan paniscus), born in the United States in 1980, passed away at the age of 44 in March of last year. He spent the majority of his life at the Ape Initiative in Des Moines, Iowa, where he became renowned for his ability to communicate by pointing to symbols on a communication board.

In the year leading up to his death, Amalia Bastos and her team at the University of St. Andrews in the UK conducted a series of experiments to examine whether Kanzi, alongside his exceptional language abilities, could engage in what researchers term “secondary representation.” This cognitive skill encompasses the ability to conceive alternate realities and occasionally share these pretenses with others, akin to early human development.

Bastos explains that children, by ages 2 or 3, can mentally track the imaginary flow of liquids between containers, discerning where the “tea” is located. “This was exactly the scenario we devised to assess Kanzi’s cognitive abilities in non-human animals.”

During the initial stage of the experiment, researchers pretended to pour imaginary juice into two empty cups, then pretended to empty one cup and asked Kanzi which cup he preferred. Remarkably, he selected the cup that he believed still contained the fictional juice more than two-thirds of the time.

Bastos notes, “If Kanzi hadn’t conceived of the ‘imaginary juice’ during the experiment, he would have selected one of the two empty cups by chance.”

In the second phase, the researchers placed one empty cup and one filled with juice before Kanzi. He chose the cup with juice over three-quarters of the time, confirming that bonobos can differentiate between real and imaginary content.

For the third test, researchers filled one cup with real grapes, which Kanzi selected each time. They then added a pretend grape to each cup, leaving one empty. Again, Kanzi successfully identified the cup that still contained the pretend grapes over two-thirds of the trials.

Bastos emphasized that all of the work with great apes was entirely voluntary. “Kanzi’s persistence during trials, even without tangible rewards, indicates he must have found some enjoyment in the activity.”

Gisela Kaplan, a researcher from the University of New England in Armidale, Australia, remarked that the experiment “demonstrates that bonobos are capable of understanding pretense and actively participating in the game.”

“The research design is straightforward, mimicking children’s play scenarios, like serving tea in a dollhouse, where they enact drinking tea and offering imaginary cake,” she elaborates.

Miguel Llorente, a professor at the University of Girona in Spain, hailed Kanzi as “a fellow Einstein” while seeking to understand the origins and mechanisms of such imaginative capabilities.

“Kanzi’s lifelong interaction with symbolic language and humans may have provided him with a robust cognitive framework, enabling him to enhance latent mental tools that bonobos may possess in the wild,” he asserts. “Although Kanzi epitomizes the cognitive potential of his species, his capabilities suggest that the fundamental biological basis for imagination has long existed in our common ancestor, dating back 6 to 9 million years.”