The epigenetic archaeology of human-dog companionship

Humans have coexisted with dogs for at least 20,000 years, yet the biological consequences of long-term human-dog co-residence remain poorly understood. We propose that sustained exposure to dogs may have contributed to context-dependent variation in human stress regulation, immune function, and socio-emotional neurobiology through environmentally responsive epigenetic mechanisms. Here, we define an epigenetic imprint as detectable differences in gene-regulatory marks, including DNA methylation at environmentally sensitive loci, consistent with developmental plasticity and early-life environmental calibration rather than germline inheritance. In this Commentary, we integrate evidence from genomics, neuroscience, microbiome research, evolutionary anthropology, and palaeoepigenetics to examine whether multispecies living environments may represent an under-recognised biological exposure shaping human regulatory biology. We further outline a framework to test whether archaeologically inferred dog co-residence is associated with epigenetic and regulatory signatures in ancient human populations while accounting for major ecological and demographic confounds. Overall, we argue that human-dog cohabitation provides a plausible and testable model for investigating how long-term social and ecological relationships may influence stress and immune regulation across populations.