Emerging infectious disease and the challenges of social distancing in human and non-human animals

Abstract

The 'social distancing' that occurred in response to the COVID-19 pandemic in humans provides a powerful illustration of the intimate relationship between infectious disease and social behaviour in animals. Indeed, directly transmitted pathogens have long been considered a major cost of group living in humans and other social animals, as well as a driver of the evolution of group size and social behaviour. As the risk and frequency of emerging infectious diseases rise, the ability of social taxa to respond appropriately to changing infectious disease pressures could mean the difference between persistence and extinction. Here, we examine changes in the social behaviour of humans and wildlife in response to infectious diseases and compare these responses to theoretical expectations. We consider constraints on altering social behaviour in the face of emerging diseases, including the lack of behavioural plasticity, environmental limitations and conflicting pressures from the many benefits of group living. We also explore the ways that social animals can minimize the costs of disease-induced changes to sociality and the unique advantages that humans may have in maintaining the benefits of sociality despite social distancing.

Keywords: behavioural immunity; pathogens and extinction risk; social distancing; social media; sociality; virtual communication.

Figure 1.

Potential changes in the degree of host sociality in response to EIDs, along with putative mechanisms driving the change and examples. Examples are referred to by letter and explained further in the text. Citations for each example given in parentheses

Figure 2.

Social distancing in response to disease (a) can result in severe costs for social animals. (b) Behavioural adaptations such as risk-sensitive social distancing and the maintenance of some social connections could mitigate these costs. (c) Humans have numerous potential advantages for implementing risk-sensitive social distancing and mitigating the costs of social isolation. (Online version in colour.)