Do human ‘life history strategies’ exist?

Contributions of evolutionary anthropology to understanding climate-induced human migration

Humans are able to thrive in a multitude of ecological and social environments, including varied environments over an individual lifetime. Migration-leaving one place of residence for another-is a central feature of many people's life histories, and environmental change goes hand-in-hand with migration, both in terms of cause and consequence. Climate change has amplified this connection between environment and migration, with the potential to profoundly impact millions of lives. Although climate-induced migration has been at the forefront of other disciplines in the social sciences, evolutionary anthropologists (EAs) have given it little attention. In this paper we draw upon existing literature and contribute our EA perspective to present a framework for analyzing climate-induced migration that utilizes theoretical approaches from a variety of social science disciplines. We focus on three overlapping dimensions-time, space, and severity-relevant to understanding the impact of climate change on human migration. We apply this framework to case studies from North America of people impacted by climate change and extreme weather events, including hurricanes, droughts, rising sea-levels, and wildfires. We also consider how access to both economic and social resources influence decisions regarding migration. Research focused on climate-induced human migration can benefit equally from the addition of EA perspectives and a more interdisciplinary theoretical approach.

Extrinsic and Existential Mortality Risk in Reproductive Decision-Making: Examining the Effects of COVID-19 Experience and Climate Change Beliefs

While the COVID-19 pandemic has presented an immediate risk to human life around the world, climate change poses an arguably greater—although less immediate—threat to our species’ survival. Within the framework of life-history theory (LHT), this pre-registered study investigated whether extrinsic risk (i.e., external factors that pose a risk to an individual’s life, e.g., COVID-19) and existential risk (i.e., risks with outcomes that threaten the existence of humans as a species, e.g., climate change) had similar or different relationships with reproductive decision-making. A UK representative sample of 325 participants between 18 and 35 years of age was asked to indicate their ideal number of children, ideal age to start having children, and whether their desire for a child had recently changed. Participants were asked about their experiences of COVID-19 and given a series of scales with which to assess their beliefs about climate change. In support of LHT, the study found evidence that knowing people who had been hospitalized with or died of COVID-19 was associated with a greater ideal number of children. Conversely, there was no clear evidence of a relationship between climate change beliefs and reproductive decision-making. The repercussions for understanding how we interpret and respond to different forms of mortality risk are discussed.

Married Too Young? The Behavioral Ecology of ‘Child Marriage’

For girls and women, marriage under 18 years is commonplace in many low-income nations today and was culturally widespread historically. Global health campaigns refer to marriage below this threshold as ‘child marriage’ and increasingly aim for its universal eradication, citing its apparent negative wellbeing consequences. Here, we outline and evaluate four alternative hypotheses for the persistence of early marriage, despite its associations with poor wellbeing, arising from the theoretical framework of human behavioral ecology. First, early marriage may be adaptive (e.g., it maximizes reproductive success), even if detrimental to wellbeing, when life expectancy is short. Second, parent–offspring conflict may explain early marriage, with parents profiting economically at the expense of their daughter’s best interests. Third, early marriage may be explained by intergenerational conflict, whereby girls marry young to emancipate themselves from continued labor within natal households. Finally, both daughters and parents from relatively disadvantaged backgrounds favor early marriage as a ‘best of a bad job strategy’ when it represents the best option given a lack of feasible alternatives. The explanatory power of each hypothesis is context-dependent, highlighting the complex drivers of life history transitions and reinforcing the need for context-specific policies addressing the vulnerabilities of adolescence worldwide.