The evolution of group living: mathematical and empirical approaches to understanding sociality

Why individuals live in groups, given the many automatic costs of group living, is a fundamental question in behavioral ecology. My approach is to search for general explanations for sociality, while also considering the details of natural history that can help explain group living in particular sets of species or under particular conditions. For example, in a paper in Behavioral Ecology (Stern & Dickinson 2016), I used mathematical modeling to show how cooperative breeding, a form of group living in which more than two adults care for the young, can be maintained when high rates of mating outside the pair band lead to reduced relatedness between the young and potential helpers. We parameterized the model using data from Professor Janis Dickinson's long-term study of western bluebird behavioral ecology, showing how the model can be tailored to particular systems in order to generate empirically relevant predictions. 

Learn more:
Stern CA, Dickinson JL (2016) Effects of load-lightening and delayed extra-pair benefits on the fitness consequences of helping. Behavioral Ecology 27: 1078-1086. Article
Dickinson JL, Akçay C, Ferree ED, Stern CA (2016) A hierarchical analysis of incest avoidance in a cooperative breeder. Behavioral Ecology 27: 1132-1140. Article
Dickinson, JL, Akçay C, Ferree ED, Stern CA (2016) Western bluebirds: lessons from a marginal cooperative breeder. In: Koenig WD and Dickinson JL (eds.) Cooperative Breeding in Vertebrates: Studies of Ecology, Evolution, and Behavior, pp. 19-38. Cambridge: Cambridge University Press.

Riehl CP, Stern CA (2015) How cooperatively breeding birds identify relatives and avoid incest: new insights into dispersal and kin recognition. BioEssays 37:1303-1308. Article
Dickinson JL, Ferree ED, Stern CA, Swift R, Zuckerberg B (2014) Delayed dispersal: teasing apart the importance of resources and parents. Behavioral Ecology 25:843-851. PDF

Inter-group cooperation in human societies

The factors that promote cooperation within groups are fairly well-understood, but we do not yet know whether these processes simply scale up to cooperation between groups, or whether intra- and inter-group cooperation are qualitatively different. Cooperation across group boundaries is particularly important for human societies, for example in management of resources used by multiple groups such as grazing land or fisheries, and understanding which social structures or cultural practices can stabilize inter-group cooperation is crucial for environmental conservation. I am co-leading a study of inter-group cooperation that pairs mathematical modeling with empirical studies of Alaska Native societies, in collaboration with Dr Jessie Barker of the Aarhus Institute for Advanced Studies. This project is funded by our National Science Foundation grant "EAGER: Cooperation across cultural groups: scaling up from local to global cooperation". Additional collaborators on this project include Dr Vanessa Ferdinand (Santa Fe Institute) and Dr Djuke Veldhuis (Aarhus Institute for Advanced Studies).

Learn more: