20.10.2017 change 06.11.2017

Prof. Trojan: Altruism among chimpanzees depends on status and sex

Photo: Fotolia Photo: Fotolia

Altruism among chimpanzees varies depending on status and sex, it is also an individual trait. These are the conclusions drawn from the two-year study of these apes - the closest evolutionary relatives of man - by psychologist Prof. Maciej Trojan from Nicolaus Copernicus University in Toruń.

"There are theories that explain the genesis and course of altruistic and pro-social behaviours in different species. We know that they are particularly important in fixed social groups. In nature, as a rule, if an individual encounters another individual only once, egoism is the best strategy. It does not matter if I fool him or help him - or if he helps or fools me, because it does not carry long-term consequences. But when I am in a fixed group - socially attached between someone and someone, all social relationships between members of the group are very important. I might want to behave in an egoistic way, but it is a short-term strategy, because I soon find myself ostracized by others, being categorized as one that takes and does not help" - Prof. Trojan emphasized in an interview with PAP.

The scientist noted that previous studies in rats had already indicated that one animal would do anything to free another from the trap - provided the trapped rat belonged to the same group. Otherwise the animal would not react to entrapment of another rat.

Professor The Trojan from the Department of Ethology and Comparative Psychology at the Nicolaus Copernicus University and his co-workers checked the altruistic reactions of chimpanzees - the closest animal relatives of man. In the study, they chose the paradigm of social behaviour research, "which assumes that in this case altruistic behaviour is extremely low-cost" - he said.

Research conducted in Warsaw zoological garden took two years. While working with apes, researchers were not physically present in the same room (their presence as "new people" could affect animal behaviour); zoo carers were requested to perform some of the activities, and the events were recorded by cameras.

In the work with apes researchers used bottle caps in two colours - red and green, which the animals gave the carers in return for food (such as grapes). They had been taught that before. Chimpanzee giving a green cap meant that the treat was given to both that chimpanzee and another chimpanzee nearby. In the case of the return of a red cap, only the chimpanzee that gave the cap was rewarded. Which means that in both cases - regardless of their reaction and behaviour - the ape that gave the cap received a treat.

"We assume that if there were a third colour that would mean food only for the other chimpanzee and not for the one giving the cap, it would be out of the game immediately, as the cost would be too great. Chimpanzee would not decide to go hungry to feed his neighbour in the cage. In our study, in the situation where the chimpanzee always eats and gets a reward, the distribution of caps should be random. But it wasn\'t" - explained the scientist.

With a two-year observation, the researchers found that when there was no other ape near the chimpanzee, it would give "tokens" at random. However, when another individual appeared nearby - the distribution ceased to be random.

"It does not mean that it was always green. We have noticed that chimpanzees have tendencies associated with social status, and the higher the status, the higher the level of altruism that does not cost much. The lower level of altruism corresponded to the lower the position in the community, as in +I do not care, so why should I help someone?+" - said the scientist.

"The greatest pro-sociality in our game was when males played with females and vice versa - females with males. This can be explained by the fact that males may be more inclined to share something with females because they have something to gain. We saw gender differences, but also personal ones. There are naturally more pro-social individuals among chimpanzees, as well as less pro-social ones" - added Prof. Trojan.

"It seems to us that many research groups failed to get similar results because they did not activate both chimps in the game, they allowed only one to give the +token+, and the second chimp was not focused on the token game. In our system individuals playing in pairs would change roles every often, and perhaps that is why our results are more consistent" - emphasised the scientist from the Nicolaus Copernicus University.

In his view, these results allow to study the evolutionary roots of altruism in human life.

"We were once a group like chimpanzees, our closest evolutionary relatives. Their behaviour is at the root of our pro-social behaviour. That is why we are affected by the altruism of kinsmen and we are more eager to help relatives than strangers; and also on the basis of reciprocity, when someone also helps us. Of course, we went further and there are altruistic attitudes, which can not be explained in this way. There really are people who help everyone without anything to gain. But evolutionary mechanisms explain the vast majority of altruistic behaviours occurring in humans" - concluded Prof. Trojan. (PAP)

Author: Tomasz Więcławski

Editor: Anna Ślązak

PAP - Science and Scholarship in Poland

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