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.
Cordoni and Norscia observed 16 red-necked wallabies from the Tierpark Zoo of Berlin for 90 hours, recording aggressive behavior (e.g., kicking and biting) and time elapsed before reconciliation. After analysis, the researchers concluded that red-necked wallabies demonstrate reconciliation, usually during the first two minutes after conflict. Reconciled wallabies (aggressors and victims) showed less anxiety (measured by amount of self-scratching) and less repeated attack. Author Mary Bates wrote a pop article summarizing the original study, highlighting results, and discussing the importance of reconciliation. Bates echoed the study’s discussion, stating that wallabies analyze the costs and benefits of reconciliation and weigh the probability of future conflict and injury.
The articles shared all results, organization, and unbiased voice. The pop article essentially summarized the original study. However, the articles varied in depth. The media article didn’t include statistical tests or specific measurements. The media article also gave more information on why wallabies may reconcile (to share space peacefully). The original study emphasized differences between reconciliation in eutherian mammals and its findings in wallabies (for example, the original study results deviated from the Valuable Relationship Hypothesis).
I appreciated the well-crafted synthesis of the original study. The authors emphasized that this was the first study investigating reconciliation in marsupials, and that they were first unsure of whether marsupials (or at least red-necked wallabies) follow the Valuable Relationship Hypothesis. This recurring theme in the methods and results of the study gave insightful implications about the data. Furthermore, after the results were presented, the authors gave insightful implications of them. Because the results deviated from the Valuable Relationship Hypothesis, the authors suggested kinship may have little influence on social bonding and interactions (at least in marsupials).
While I enjoyed most aspects of the original study, the authors could have given the reader more to consider in the discussion. They expressed the need for more comparison studies between eutherian and metatherian animals to investigate convergent and divergent adaptions, and selection for reconciliation. The authors didn’t propose a study testing evolutionary roots of reconciliation, which would’ve been appreciated.
The pop article was destined for media as the first evidence of reconciliation by marsupials. The pop article language was accessible for anyone with basic science knowledge, and although the pop article didn’t explicitly define reconciliation, one could infer the meaning from the context provided (as well as an understanding of reconciliation in humans).
Before this study, I hadn’t considered reconciliation outside of kinship necessary. As related individuals share some proportion of genes, I understood the need for reconciliation in parents, offspring, siblings, grandparents, and other relatives. I now understand how social behavior (e.g., group foraging and care) necessitates reconciliation in unrelated individuals, as individuals most likely won’t share resources with those whom they cannot demonstrate affinitive behavior.
Works Cited
Bates, Mary. “Peace-Making Wallabies Choose When to Reconcile After a Fight.” Wired.com. Conde Nast Digital, 10 Feb. 2014. Retrieved 08 Mar. 2014.
Cordoni G, Norscia I (2014) Peace-Making in Marsupials: The First Study in the Red-Necked Wallaby (Macropus rufogriseus). PLoS ONE 9(1): e86859. doi:10.1371/journal.pone.0086859
de Waal FBM, van Roosmaleen A (1979) Reconciliation and consolation among chimpanzees. Behav Ecol Sociobiol 5: 55–66. doi: 10.1007/bf00302695
Wittig, Roman M., and Christophe Boesch. (2005) How to Repair Relationships – Reconciliation in Wild Chimpanzees (Pan troglodytes). Ethology 111: 736-763. doi: 10.1111/j.1439-0310.2005.01093.x
Tags: marsupials, social behavior