Bonobo Kanzi Plays Pretend in Lab Tea Party Tests

Scientists at a research lab have run tests showing a bonobo ape named Kanzi can take part in pretend play. The 43-year-old ape joined what looked like a tea party with empty cups and pitchers. He pointed to the spots where researchers pretended to pour juice or place grapes. The work took place over several sessions with Kanzi, who lives in a lab setting in the United States.

Background

Kanzi grew up in a lab where he learned to talk to people using symbols on a board. He presses buttons with pictures to mean words, and he mixes them to say new things. He also makes basic tools from stones. Researchers have seen wild chimpanzees carry sticks like babies or drag pretend blocks after real ones. Lab chimps and bonobos have done similar things when people guide them. But no one proved apes know the difference between real and make-believe. Past stories were just observations, not strict tests. People wondered if apes copy humans or mix up fake with real. To check this, the team set up games like ones used with two-year-old kids, who turn sticks into swords or hold tea parties with air.

Bonobos live in forests of central Africa. They share a common ancestor with humans from six to nine million years ago. Kanzi's skills come from years around humans, which makes him good for these tests. He stayed interested through many trials and picked right most times without learning on the spot.

Key Details

The main test used an empty pitcher and two cups. Researchers pretended to pour juice from the pitcher into both cups, then acted like they drank from one, leaving pretend juice in the other. They asked Kanzi, 'Which cup do you want?' He pointed to the one with the leftover pretend juice 68 percent of the time. This happened in sessions without rewards to see if he got it.

Juice Test Checks Real vs. Fake

To make sure Kanzi knew pretend from real, they poured actual juice in one setup. Kanzi picked the real juice nearly 80 percent of the time when both real and pretend were options. He did not get upset when pointing to pretend spots with no reward, which shows he did not think it was real.

In another game, they used fake grapes. Researchers pretended to put grapes in two jars, then took some from one. Kanzi pointed to the jar with more pretend grapes 69 percent of the time. Again, no signs he mixed it up with real food.

Kanzi got it right on his first try each time. Stats showed no sign he learned during the tests. He stayed motivated, getting almost all training trials right when rewards came.

"What's really exciting about this work is that it suggests that the roots of this capacity for imagination are not unique to our species." – Christopher Krupenye, Johns Hopkins University

The study ran three experiments to rule out other ideas. Kanzi responded by pointing when people spoke to him. All this happened in a controlled lab with fences between Kanzi and the researchers.

What This Means

This work points to apes forming mental pictures of pretend things. Kanzi tracked where fake juice or grapes moved, even when no real item was there. It suggests the skill to imagine started long ago, shared with our ape relatives. Human kids do this by age two, turning rooms into castles or toys into friends. If apes do it too, then imagination may not set humans apart as much as thought.

Some experts want more proof. They say picking the right spot shows he sees the pretend act, but maybe not that he holds the idea in his mind like kids. One researcher said he would like to see Kanzi pour pretend juice himself to be sure. The tests used words to guide Kanzi, which helped since he understands speech.

The setup could now test other apes. Wild chimps with sticks as babies might show early hints of this. Lab apes without human raising could tell if growing up with people matters. It opens doors to study how minds work across species. Bonobos like Kanzi push what we know about animal thoughts. Findings like these change views on evolution and what makes humans special. Researchers plan to try the games with more apes to see if it's common or just in ones like Kanzi.