Complex social interactions have been a cornerstone of human evolution, altering how we respond to stress and immune challenges, the environment, and one other. Our history as hunter/gatherers has much to do with patterns in behavior and metabolism that are not always adaptive in modern contexts, and adverse social circumstances have been linked with heart disease, cancer, chronic inflammation, neurodegenerative conditions, susceptibility to viral infection, metabolic illness, and other health issues.
Certain genes are emerging as especially sensitive to social inputs, which can alter cell signaling, gene expression and its regulation, and epigenetic modulation of DNA. Polymorphisms in ‘socially-sensitive’ genes add a further dimension to the highly variable ways we individually react to social dynamics.
Social interactions represent a major infusion of information that is critical for the survival and evolution of a species as well as for each individual. Early-life exposures are especially impactful, and social inputs that strongly influence gene regulation can range from social instability, traumas, and bereavement to low socioeconomic status, difficult relationships, social failures, and events that affect large populations.
Environmental and social information is gathered and processed through neural, psychological, hormonal, and immune pathways, leading to adaptations in genetic regulation of cell function that are aimed at addressing new living circumstances. This data can influence gene expression by altering gene transcription (the ‘reading’ of genes and production of associated proteins) or through epigenetic modification of DNA and chromosomes to silence or amplify their genetic messaging.
Studies conducted in humans and other mammals have discovered a consistent pattern of adjustment in gene expression that alters immune balance after experiences that are perceived as stressful for extended periods of time. This pattern is characterized as proinflammatory and yet suppressive of the body’s normal reaction to viruses, and it is hypothesized that it may have proven more adaptive for survival earlier in the course of human evolution.
Social Dynamics Guide Gene Expression and Immune Balance
Through social dynamics, humans regulate the genomes of other humans, and our ever-changing social ecology contributes to human evolution. This species-wide genomic network of influence is termed our shared “metagenome,” and it reflects how social interactions cultivate adaptation in human cognitive and metabolic function.