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Norway rats reciprocate help according to the quality of the help they received

Date:
February 25, 2015
Source:
University of Bern
Summary:
Non-human animals consider the value of previously received help when deciding whether to help a social partner, according to a new study in rats. Until now, it was unclear whether animals other than humans would consider the the value of a help received (independent of other parameters such as the partner’s identity or effort taken) when deciding how to reciprocate.
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Rats provided by a social partner with attractive food, such as a banana, return this favour more readily than if the previous reward was rather unappealing, such as a carrot.
Credit: Vassilissa Dolivo

Research performed at the University of Bern indicates that animals beyond Homo sapiens consider the value of previously received help when deciding whether to help a social partner.

Reciprocal exchange of services and commodities among conspecifics is common, and has been observed for instance in primates, vampire bats and rats. For humans, a predominant factor influencing the motivation to reciprocate help is the individual’s perceived benefit resulting from the received help. Until now, it was unclear whether animals other than  humans would consider the the value of a help received (independent of other parameters such as the partner’s identity or effort taken) when deciding how to reciprocate.

Using Norway rats, Vassilissa Dolivo and Michael Taborsky, two researchers at the Institute of Ecology and Evolution from the University of Bern, have found that animals other than humans also reciprocate help according to the quality of help they received. The study appeared in the journal Biology Letters. According to Vassilissa Dolivo, Norway rats were chosen because of their ability to perform experimental tasks under laboratory conditions, as of their high degree of sociality in the wild and their known ability to cooperate on the basis of the decision rule of direct reciprocity – that is "helping someone who has helped you before."

Banana providers preferred

Twenty female wild-type Norway rats were tested in a variant of the prisoner’s dilemma paradigm. Each test rat received food items differing in value and attractiveness from two different social partners that provided either a preferred, "high quality" reward – pieces of banana – or a less relished, «low quality» reward – pieces of carrot. The quality of the offered food was the only variable parameter for test rats to distinguish between different cooperators.

Subsequently, the test rats could decide to provide their previous banana or carrot providers with oat flakes. "The test rats showed a clear preference to pay back help to the partner that had provided them with the preferred food", says Michael Taborsky. "They helped previous banana providers much quicker than previous carrot providers."

According to the authors, these results demonstrate that animals can consider the value of previously received help when deciding whether to help a social partner. This may have important implications for our understanding of reciprocal cooperation in nature, for which, as Vassilissa Dolivo points out, "evidence is increasing throughout vertebrates, from fishes to primates."


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Materials provided by University of Bern. Note: Content may be edited for style and length.


Journal Reference:

  1. Vassilissa Dolivo, Michael Taborsky. Norway rats reciprocate help according to the quality of help they received. Biology Letters, 2015 DOI: 10.1098/rsbl.2014.0959

Cite This Page:

University of Bern. "Norway rats reciprocate help according to the quality of the help they received." ScienceDaily. ScienceDaily, 25 February 2015. <www.sciencedaily.com/releases/2015/02/150225082735.htm>.
University of Bern. (2015, February 25). Norway rats reciprocate help according to the quality of the help they received. ScienceDaily. Retrieved May 23, 2017 from www.sciencedaily.com/releases/2015/02/150225082735.htm
University of Bern. "Norway rats reciprocate help according to the quality of the help they received." ScienceDaily. www.sciencedaily.com/releases/2015/02/150225082735.htm (accessed May 23, 2017).

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