Intergenerational transmission of parental rejection effects on survival, behaviour, and miRNA expression in owl monkeys

Parental rejection in captive primates represents severe early-life stress, yet intergenerational effects remain poorly characterised. We investigated spontaneous rejection in owl monkeys (Aotus nancymaae) across two generations using demographic records (n=1,389), behavioural observations (n=65), and blood miRNA profiling (n=47). Rejected individuals showed 51% reduced lifespan, decreased probability of reaching reproductive age, and increased morbidity throughout life. Critically, well-reared offspring of rejected parents exhibited similar reductions in survival to reproductive age and lifespan. Rejected adults displayed heightened fearfulness and aggression with reduced paternal care; offspring showed decreased locomotion and altered stress responses. Blood miRNA analysis revealed significant upregulation of mml-miR-30a-5p in female offspring-a miRNA associated with early-life stress and behavioural disorders in humans. These findings demonstrate intergenerational transmission of rejection effects on fitness and behaviour, with preliminary evidence suggesting epigenetic mechanisms are associated with this transmission, though multiple pathways likely operate.