Stay social, stay young: a bioanthropological outlook on the processes linking sociality and ageing

Abstract

In modern human societies, social interactions and pro-social behaviours are associated with better individual and collective health, reduced mortality, and increased longevity. Conversely, social isolation is a predictor of shorter lifespan. The biological processes through which sociality affects the ageing process, as well as healthspan and lifespan, are still poorly understood. Unveiling the physiological, neurological, genomic, epigenomic, and evolutionary mechanisms underlying the association between sociality and longevity may open new perspectives to understand how lifespan is determined in a broader socio/evolutionary outlook. Here we summarize evidence showing how social dynamics can shape the evolution of life history traits through physiological and genetic processes directly or indirectly related to ageing and lifespan. We start by reviewing theories of ageing that incorporate social interactions into their model. Then, we address the link between sociality and lifespan from two separate points of view: (i) considering evidences from comparative evolutionary biology and bioanthropology that demonstrates how sociality contributes to natural variation in lifespan over the course of human evolution and among different human groups in both pre-industrial and post-industrial society, and (ii) discussing the main physiological, neurological, genetic, and epigenetic molecular processes at the interface between sociality and ageing. We highlight that the exposure to chronic social stressors deregulates neurophysiological and immunological pathways and promotes accelerated ageing and thereby reducing lifespan. In conclusion, we describe how sociality and social dynamics are intimately embedded in human biology, influencing healthy ageing and lifespan, and we highlight the need to foster interdisciplinary approaches including social sciences, biological anthropology, human ecology, physiology, and genetics.

Keywords: Ageing; Human evolution; Lifespan; Physiology; Sociality; Stress.

Fig. 1

Schematic representation of the narrative approach adopted in this review. The approach is based on the analysis of the interplay between sociality and biological processes that are central to the process of healthy ageing and that help to explain the extended lifespan that is a characteristic of our species. The relationship between these factors has been subject to continuous modulation throughout the course of human evolution

Fig. 2

Link between social environment and extended lifespan in pre-industrial society. The lens of comparative evolutionary biology provides evidences of the social determinants that favours biological mechanisms (in particular the evolution of neoteny and larger brains) responsible for the differences in extended lifespan between modern human hunter-gatherers and other primates. The lens of the human ecology provides evidences of the social determinants that favours biological mechanisms (in particular the delayed maturity and the extended juvenile phase) responsible for the differences observed among human groups living in different ecological niches

Fig. 3

Social dynamics impacts on evolutionary conserved mechanisms of stress response that involved HPA (hypothalamic–pituitary–adrenal) and SAM (sympathetic-adrenomedullary) axes. The effect of sociality—in reason of the systemic nature of stress response—has been observed in immune, neuroendocrine, and cardiovascular systems. These biological changes that could include both genetic and epigenetic changes can ultimately influence lifespan