Animal minds Evolution News

Another “altruistic chimps” story that doesn’t demonstrate what is claimed

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One colored token could be exchanged with an experimenter for treats for both members of the pair (prosocial); the other colored token would result in a treat only for the chooser (selfish)/Emory University

Following hard on the heels of this study, “Sharing is learned in humans, not in chimps,” we hear from the Yerkes Primate Center “Chimpanzees Are Spontaneously Generous After All, Study Shows” (ScienceDaily, August 9, 2011):

n the current study, Dr. Horner and colleagues greatly simplified the test, which focused on offering seven adult female chimpanzees a choice between two similar actions: one that rewards both the “actor,” the term used in the paper for the lead study participant, and a partner, and another that rewards only the actor/chooser herself. Examples of the critically important simplified design aspects include allowing the study partners to sit close together and ensuring conspicuous food consumption, which the researchers achieved by wrapping pieces of banana in paper that made a loud noise upon removal.

In each trial, the chooser, which was always tested with her partner in sight, selected between differently colored tokens from a bin. One colored token could be exchanged with an experimenter for treats for both members of the pair (prosocial); the other colored token would result in a treat only for the chooser (selfish). All seven chimpanzees showed an overwhelming preference for the prosocial choice. The study also showed the choosers behaved altruistically especially towards partners who either patiently waited or gently reminded them that they were there by drawing attention to themselves. The chimpanzees making the choices were less likely to reward partners who made a fuss, begged persistently or spat water at them, thus showing their altruism was spontaneous and not subject to intimidation.

In short, as a social species, chimpanzees do not readily break up a harmonious group. The chimp partners who spat water were thereby revealing that they were not harmonious group members. No chimpanzee was giving her own reward to another.

What keeps this stuff going anyway? Oh yes,

These results, however, confirm chimpanzee altruism in a well-controlled experiment, suggesting human altruism is less of an anomaly than previously thought.

The study authors next plan to determine whether the altruistic tendency of the chimpanzees towards their partners is related to social interactions within the group, such as reciprocal exchanges of food or social support.

Thoughts as to what they’ll find? Or if, assuming they don’t find what they are looking for, we will hear much about it?

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