Great apes make much more sophisticated decisions than assumed

Chimpanzees, orangutans, gorillas and bonobos make more sophisticated decisions than was previously thought, a new study has suggested.

Max Planck Institutes researchers suggested that great apes weigh their chances of success, based on what they know and the likelihood to succeed when guessing.

The findings may provide insight into human decision-making as well.

The team led by Daniel Haun of the MPI for Psycholinguistics (Nijmegen) and Evolutionary Anthropology (Leipzig), investigated the behaviour of all four non-human great ape species.

The apes were presented with two banana pieces: a smaller one, which was always reliably in the same place, and a larger one, which was hidden under one of multiple cups, and therefore the riskier choice.

The researchers found that the apes’ choices were regulated by their uncertainty and the probability of success for the risky choice, suggesting sophisticated decision-making.

Apes chose the small piece more often when they where uncertain where the large piece was hidden. The lower their chances to guess correctly, the more often they chose the small piece.

The researchers also found that the apes went for the larger piece – and risked getting nothing at all – no less than 50percent of the time.

This risky decision-making increased to nearly 100percent when the size difference between the two banana pieces was largest.

While all four species demonstrated sophisticated decision making strategies, chimpanzees and orangutans were overall more likely to make risky choices relative to gorillas and bonobos.

The precise reason for this discrepancy remains unknown.

“Our study adds to the growing evidence that the mental life of the other great apes is much more sophisticated than is often assumed,” Haun concluded.

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The finding has been published on December 21 in the online journal PLoS ONE. (ANI)

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