7. Contextual Effects on Fertility and Mortality

In this chapter I explore the influence of the local ecology, also known as contextual or area effects, on two focal demographic outcomes, fertility and mortality. I start by outlining why ecological effects have been of interest to evolutionary scholars, provide a brief overview of life history theory as a theoretical framework and the type of data from traditional, small-scale populations that have been used to test predictions. Key evolutionary concepts such as extrinsic mortality risk and phenotypic plasticity are explained. I then compare and contrast this perspective to how contextual effects have been tackled by non-evolutionary scholars within demography and related disciplines, drawing on studies mainly from high-income contexts based on broad population register data. In the final part of the chapter I lay out some challenges for this research area, which include addressing selection biases and attaining a greater understanding of underlying causal mechanisms. Future research is likely to be more fruitful if evolutionary and non-evolutionary lines of enquiry become increasingly integrated.