When cooperation begets cooperation: the role of key individuals in galvanizing support.
Life abounds with examples of conspecifics actively cooperating to a common end, despite conflicts of interest being expected concerning how much each individual should contribute. Mathematical models typically find that such conflict can be resolved by partial-response strategies, leading investors to contribute relatively equitably. Using a case study approach, we show that such model expectations can be contradicted in at least four disparate contexts: (i) bi-parental care; (ii) cooperative breeding; (iii) cooperative hunting; and (iv) human cooperation. We highlight that: (a) marked variation in contributions is commonplace; and (b) individuals can often respond positively rather than negatively to the contributions of others. Existing models have surprisingly limited power in explaining these phenomena. Here, we propose that, although among-individual variation in cooperative contributions will be influenced by differential costs and benefits, there is likely to be a strong genetic or epigenetic component. We then suggest that selection can maintain high investors (key individuals) when their contributions promote support by increasing the benefits and/or reducing the costs for others. Our intentions are to raise awareness in--and provide testable hypotheses of--two of the most poorly understood, yet integral, questions regarding cooperative ventures: why do individuals vary in their contributions and when does cooperation beget cooperation?
Department of Psychology, Yale University, 2 Hillhouse Avenue, New Haven, CT 06520, USA Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA 02138, USA Department of Psychology, Boston College, Chestnut Hill, MA 02467, USA katherine.mcauliffe@yale.edu.
Katherine
K
McAuliffe
Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA 02138, USA.
Richard
R
Wrangham
Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA 02138, USA Program for Evolutionary Dynamics, Harvard University, 1 Brattle Square, Cambridge, MA 02138, USA.
Luke
L
Glowacki
Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA 02138, USA Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Treliever Road, Penryn, Cornwall TR10 9FE, UK.
Andrew F
AF
Russell
D000533:Altruism; D000818:Animals; D003299:Cooperative Behavior; D003466:Cultural Characteristics; D005190:Family; D006379:Helping Behavior; D006801:Humans
biological market theory; coercion; cooperative matching; incomplete compensation; information asymmetry; shifting cost-benefit functions