Bonobos offer insight into early human evolution

Bonobos are a highly endangered species of great ape and are one of humans’ two closest living relatives.

As a result, bonobos are often used in scientific studies because of their close relation to humans. Behavioral studies of bonobos and chimpanzees can offer insights into human evolution and how and when humans adapted certain traits.

A new study has now found that humans and bonobos differ in a very distinct way: the preference for helpers and hinderers in an otherwise peaceful and co-operative society.

Humans show a preference for helpers from a very young age, and even infants are able to differentiate helpers from hinderers, preferring the former. It makes sense as helpers are important to co-operation which is a core part of human interaction.

Bonobos however, although equally able to distinguish hinderers from helpers, prefer hinderers.

Researchers from Duke University led by Christopher Krupenye and Brian Hare were motivated to study bonobos because of a 2007 study that showed how humans prefer helpers. The researchers were curious if this was a trait developed early or later on in human evolution.

The results of the study suggest that we grew to prefer helpers after our species diverged from  apes.

The reason bonobos have an opposite preference could be related to the important role of dominance in their society.

Hinderers, according to the researchers, may come across as more dominant which is why bonobos are drawn to hinderers rather than helpers.

“Our experiments show that the issue is much more nuanced. Bonobos are highly socially tolerant in food settings and help and cooperate with food in ways that we don’t see in chimpanzees. However, dominance still plays an important role in their lives,” said Krupenye.

The study took place at Lola ya Bonobo, a bonobo sanctuary in the Democratic Republic of the Congo.

The researchers conducted several experiment to test how bonobos interacted with helpers and hinderers.

For one experiment, the bonobos were shown pictures of two-dimensional animated shapes that helped or hindered each other. The shapes were then cut out and placed on a slice of apple.

The researchers observed which apple piece the bonobos chose to reach for first. Another experiment allowed the bonobos to choose between interacting with a human that they had observed either helping or hindering. The bonobos showed a preference for the hinderer everytime.

Cooperation is a fundamental part of human nature and the researchers say their findings show that it may be an exclusively human trait developed later in our evolution.

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By Kay Vandette, Earth.com Staff Writer

Image Credit: Christopher Krupenye