Competition for limited resources has fueled physical conflict in mammals and other animals. While some physical conflicts result in death of a competitor, individuals often return to peaceful living through reconciliation. Reconciliation is defined as “the first exchange of affinitive behavior between opponents after conflict” (de Waal and van Roosmaleen, 1979). Examples of affinitive behavior include sharing resources, feeding each other, and cuddling (Cordoni and Norscia, 2014). Many mammals follow the Valuable Relationship Hypothesis, which states that kin demonstrate reconciliation more often than unrelated individuals, assuming a previously cordial relationship (Cordoni and Norscia, 2014). Reconciliation reduces stress and aggression, and maintains high-value relationships (such as those with kin) in wild chimpanzees and other mammals (Wittig and Boesch, 2005). I reviewed a study by Giada Cordoni and Ivan Norscia of the University of Pisa involving red-necked wallabies (Macropus rufogriseus) and reconciliation. This was the first study conducted to provide evidence of reconciliation in marsupials. (more…)