Dogs have been bred and trained to assist and cooperate with humans since hundreds of generations. They are used for protection, as shepherds, to search for things and people, or to assistant people in need. But dogs are also able to cooperate with conspecifics, for instance when they help each other to obtain food, as shown by a study of the Institute of Ecology and Evolution. 

Do dogs use similar cooperation mechanisms as humans? 

Human motivation to help others increases when they receive help themselves. They may either return received help to the previous donor, which is called "direct reciprocity", or they may become helpful overall upon received help, which is referred to as "generalized reciprocity". When driving a car, for example, we behave more generously toward others if we have experienced generous behaviour before, irrespective of the identities of previous benefactors and prospective beneficiaries.

Similar behaviour has been demonstrated in Norway rats in several studies led by Prof. Michael Taborsky at the Division of Behavioural Ecology of the University of Bern. It is currently unknown, however, how widespread this generalized form of reciprocal cooperation is in animals. Clarifying how animals respond to received help may provide insight into the evolutionary roots of reciprocal cooperation in humans, which is arguably the key factor in our ecological success.

Swiss army dogs help a conspecific to get food

Swiss army dogs were trained to pull a rope in order to provide a social partner in the neighbouring kennel with food. The pulling dog did not get food itself, but it could benefit if the social partner subsequently returned the helping action. The experimental dogs were unrelated and unfamiliar with each other, to exclude potential influences of kinship and familiarity. The tested dogs responded strongly to experienced aid. They helped a partner more after receiving help than after receiving no help. But was this due to a generally increased propensity to help conspecifics, or did this reflect the return of a favour to a particular individual – in other words, did dogs behave according to direct or generalised reciprocity? 

Direct or generalised reciprocity?

To answer this question, experimental dogs were either tested with the same dog that had helped them before to obtain food, or with another, unfamiliar conspecific. Surprisingly, the experimental dogs did not discriminate between these two situations. They based their decision to help a social partner upon the experience they had received, irrespective of the identities of the previous donor and the prospective receiver. 

Hence, dogs seem to apply the decision rule characterizing generalized reciprocity: "help anyone if helped by someone", but not the direct reciprocity rule: "help someone who has helped you before".

Dogs are the first species of animals tested for these different mechanisms that apparently applies only the generalized form of reciprocal cooperation.