Mongooses remember and reward helpful friends

May 28, 2018, University of Bristol

Dwarf mongooses remember previous cooperative acts by their group mates and reward them later, according to new work by University of Bristol researchers, published today in the journal Proceedings of the National Academy of Sciences.

Market trade was once considered the domain of humans but the exchange of goods and services is now widely recognised in other animals. What the new research shows is that mongooses have sufficient cognitive ability to quantify earlier acts of cooperation and to provide suitable levels of delayed rewards.

Senior author, Professor Andy Radford from Bristol's School of Biological Sciences, said: "Humans frequently trade goods and can track the amount they owe using memories of past exchanges. While nonhuman animals are also known to be capable of trading cooperative acts immediately for one another, more contentious is the possibility that there can be delayed rewards."

Lead author, Dr. Julie Kern, also from Bristol, added: "There have been hardly any suitable experimental tests on wild animals, especially non-primates. By working with groups of dwarf mongooses habituated to our close presence, we could collect detailed observations and conduct experimental manipulations in natural conditions."

The study is the first to provide experimental evidence in a wild non-primate population for delayed contingent cooperation—providing a later reward to an individual for the amount of cooperation it has performed. It also offers convincing evidence of cross-commodity trading, whereby individuals reward one type of cooperative behaviour with a different cooperative act. In this case, grooming was traded for sentinel behaviour, which involves an individual adopting a raised position to look out for danger and warning foraging groupmates with alarm calls.

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