Applying an evolutionary mismatch framework to understand disease susceptibility

Evolutionary perspectives on substance and behavioural addictions: Distinct and shared pathways to understanding, prediction and prevention

Addiction poses significant social, health, and criminal issues. Its moderate heritability and early-life impact, affecting reproductive success, poses an evolutionary paradox: why are humans predisposed to addictive behaviours? This paper reviews biological and psychological mechanisms of substance and behavioural addictions, exploring evolutionary explanations for the origin and function of relevant systems. Ancestrally, addiction-related systems promoted fitness through reward-seeking, and possibly self-medication. Today, psychoactive substances disrupt these systems, leading individuals to neglect essential life goals for immediate satisfaction. Behavioural addictions (e.g. video games, social media) often emulate ancestrally beneficial behaviours, making them appealing yet often irrelevant to contemporary success. Evolutionary insights have implications for how addiction is criminalised and stigmatised, propose novel avenues for interventions, anticipate new sources of addiction from emerging technologies such as AI. The emerging potential of glucagon-like peptide 1 (GLP-1) agonists targeting obesity suggest the satiation system may be a natural counter to overactivation of the reward system.

Microbial transmission in the social microbiome and host health and disease

Although social interactions are known to drive pathogen transmission, the contributions of socially transmissible host-associated mutualists and commensals to host health and disease remain poorly explored. We use the concept of the social microbiome-the microbial metacommunity of a social network of hosts-to analyze the implications of social microbial transmission for host health and disease. We investigate the contributions of socially transmissible microbes to both eco-evolutionary microbiome community processes (colonization resistance, the evolution of virulence, and reactions to ecological disturbance) and microbial transmission-based processes (transmission of microbes with metabolic and immune effects, inter-specific transmission, transmission of antibiotic-resistant microbes, and transmission of viruses). We consider the implications of social microbial transmission for communicable and non-communicable diseases and evaluate the importance of a socially transmissible component underlying canonically non-communicable diseases. The social transmission of mutualists and commensals may play a significant, under-appreciated role in the social determinants of health and may act as a hidden force in social evolution.