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Robert Quinlan, Washington State University

October 10 @ 3:00 pm - 4:15 pm MDT

Robert Quinlan, Washington State University

Seminar Title: Unpredictable Environments, Culture Change and Human Life History

Abstract: Human life history research concerns a constellation of physiological and psychological mechanisms that regulate trade-offs in the allocation of energy and attention in response to environmental conditions. Two fundamental trade-offs include the quality vs quantity of offspring and the value of present vs future reproduction.  I briefly review evidence for these trade-offs in small-scale, natural fertility populations around the world. Not one study shows the predicted quality-quantity trade-off in offspring such that reduced fertility maximizes individual fitness as observed in some experimental manipulations of brood size in non-human animals.  Three hypotheses account for null results: (1) unmeasured alloparental care could mask costs of reproduction; (2) optimal fertility may be a property of extended family households; and (3) the quality-quantity trade-off may not hold in unpredictable environments where expected outcomes of allocation decisions are unknown.  Evidence for trade-offs between present vs future reproduction is more consistent with theoretical predictions indicating that in some unpredictable environments people reproduce at younger ages, have greater overall fertility, and exhibit psychological characteristics geared toward delay-discounting, reward seeking, and impulsivity. However, results are inconsistent across populations at varying levels of economic development such that in some changing and unpredictable environments people delay rather than accelerate reproduction. I suggest that, in addition to well-known energy constraints on reproduction, specific responses of larger social ecological systems to perturbations may explain these inconsistent results. I present an example from recent research among Sidama agro-pastoralists in Ethiopia showing that theoretically expected life history responses to unpredictable events depend on climate change-related regional differences in livelihoods. Finally, I conclude that some life history mechanisms may promote household and community resilience in addition to regulating reproductive decisions.

More About the Speaker: Robert Quinlan is a professor in Evolutionary and Cultural Anthropology at Washington State University. His research focuses on the role of environmental risk in shaping human reproduction, livelihood, family relations, and cognition in small-scale production systems.

Learn more about Robert and his research.