Friday, December 13, 2013

Chimpanzees Are Rational, Not Conformists

himpanzees are sensitive to social influences but they maintain their own strategy to solve a problem rather than conform to what the majority of group members are doing. However, chimpanzees do change their strategy when they can obtain greater rewards, MPI researchers found. The study was published in PLOS ONE on November 28, 2013.


 Chimpanzees are known for their curious nature. They show a rich palette of learning behaviour, both individually and socially. But they are also rather hesitant to abandon their personal preferences, even when that familiar behaviour becomes extremely ineffective. Under which circumstances would chimpanzees flexibly adjust their behaviour? Edwin van Leeuwen and colleagues from the MPI's for Psycholinguistics and Evolutionary Anthropology conducted a series of experiments in Germany and Zambia to answer this question.

Wooden balls for peanuts

The researchers studied 16 captive chimpanzees at the Wolfgang Kohler Primate Research Center in Germany (Leipzig) and 12 semi-wild chimpanzees at the Chimfunshi Wildlife Orphanage Trust, a sanctuary that houses more than a hundred chimpanzees under nearly natural conditions in the north-western part of Zambia. Chimpanzees were trained on two different vending machines. A minority of the group was made familiar with one machine and the majority of group members with the other machine. Wooden balls were thrown into their enclosure; the chimpanzees could insert these balls into the machines to receive one peanut for each ball.

Van Leeuwen and his colleagues first aimed to replicate previous research and looked whether the chimpanzees in the minority group would change their behaviour toward using the vending machine that the majority of group members used. However, neither the German nor the Zambian chimpanzees gave up their strategy to join the majority. In the second study, the profitability of the vending machines was changed so that the vending machine that the minority used became more profitable, now spitting out five rewards for every ball inserted. Over time, the majority chimpanzees observed that the minority chimpanzees received more peanuts for the same effort and all but one gradually switched to using this more profitable machine.

Higher rewards

"Where chimpanzees do not readily change their behaviour under majority influences, they do change their behaviour when they can maximise their payoffs," Van Leeuwen says. "We conclude that chimpanzees may prefer persevering in successful and familiar strategies over adopting the equally effective strategy of the majority, but that chimpanzees find sufficient incentive in changing their behaviour when they can obtain higher rewards somewhere else.” “So, it's peanuts over popularity" he jokingly adds.

The researchers emphasise that these results may be dependent upon the specific trade-offs that were created by the experimental design and that chimpanzees could act differently under the pressures of life in the wild. Van Leeuwen: "Conformity could still be a process guiding chimpanzees’ behaviour. Chimpanzee females, for instance, disperse to other groups in the wild. For these females, it is of vital importance to integrate into the new group. Conformity to local (foraging) customs might help them to achieve this integration."

Link to the publication.

Contacts and sources:
Edwin van Leeuwen
Max-Planck-Gesellschaft

1 comment:

  1. What is the difference between the life that is in a cell, a chimp, a guinea pig or a human being? Do not come and vanishes in the same way, in one breath alone? Isn’t life a single indivisible movement, an information flow that builds up and changes from a common ancestor? Or perhaps is there a unique quality in human beings, a qualitative leap detached from all evolutionary processes and unrelated to the rest of life? Is it the same leap that makes the human language when differentiating between life and the rest of the universe? Also between health and disease, between life and death? Anyway, knowing the likeness between humans and chimps, what do this similarity prevent? Does it prevent jailing, killing or torturing? Or rather, thanks to likeness, can we see our eyes and voice from the outside and alive? And, can we love another, also the chimp or the guinea pig, in order to love oneself? Along these lines, a serious-funny b-book recommendation, a preview in goo.gl/rfVqw6 Just another mind leisure suggestion, far away from dogmas or axioms.

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