1. Introduction
The social environment shapes human life courses, and can generate
strong associations between sociality, health, and longevity. For
example, higher social status predicts longer lifespan (Adler et al.,
1993; Chetty et al., 2016; Hajat et al., 2011; Lantz et al., 2010;
Sapolsky, 2004; Wilkinson and Marmot, 2003), greater social support
predicts healthier aging (Antonucci et al., 2019; Béland et al., 2005;
Holt-Lunstad et al., 2010), and early life social adversity predicts
higher mortality risk (Anda et al., 2006; Ferraro et al., 2016; Hughes
et al., 2017). However, disentangling the effects of the social
environment on human life courses remains challenging due to multiple
uncontrolled (e.g., incongruencies in self-reported health; non-random
attrition) and unknown confounding factors (e.g., biased survey
information). Comparative approaches can both provide evidence
concerning the evolutionary origins of the social determinants of human
health and aging, and provide a model for the intricate interactions and
potential feedback loops between sociality and aging (Carey and Judge,
2001; Lucas and Keller, 2020). This review argues that studies on the
comparative biodemography of aging can advance our understanding of the
link between individual sociality, population-level demographic
outcomes, and the evolution of aging in humans. For this, we define
senescence as a decline in function with age and differentiate it from
health statuses which we define as deviations from such expected mean
decline. We introduce conceptual frameworks for the evolutionary
demography of aging within social contexts, discuss why current
challenges in human health and aging studies call for comparative
approaches, and describe a unifying methodological framework for the
biodemography of aging that links current research in the social
determinants of health to evolutionary demography approaches to the
fundamental rules of life history evolution.