Biology session

The evolution of cooperation is a really controversial part of ethology. Hamilton’s rule explain the phenomenon of cooperation between related individuals (kin selection theory). Among non-related individuals direct and indirect reciprocity can lead to cooperation.

In previous studies the loose-string paradigm was used to assess cooperation with chimpanzees, bonobos, elephants, hyenas. These animals solved the tests and from the controls it turned out that they understood they need their partner. In this present study I used the loose-string method to test seven male ring-tailed lemurs in the Jászberény Zoo.

An interesting question is, whether the lemurs are able to solve the test and if so, do they understand the role of their partner? Furthermore this species lives in highly social groups so the question arose, if cooperation reflects social, dominance or kinship relations?

For describing positive and agonistic behaviours I used focus animal sampling.

According to our results each individual (apart from one) performed the task successfully significantly more than chance level. In case of successful cooperations (excluding the same individual) the pairs were not formed randomly, however neither kinship nor aggressive interactions nor the strength of social relationships explained the observed pattern.

According to our preliminary results social dominance and kinship do not account for the non-random partner choice during cooperation in lemurs. There must be other underlying factors that can explain the observed pattern, such as individuals prefer cooperating with those lemurs with which they were successful during the learning phase.