To expand our understanding of the neuroendocrine mechanisms underlying human fatherhood, including its cross-cultural expression, we
investigated the hormonal correlates of fatherhood in the greater Kingston, Jamaica area. We recruited 43 men, aged 18–38, to participate: 15
single men; 16 “coresidential” fathers (men who live with their adult female partner and youngest child); and 12 “visiting” fathers (men who live
apart from their adult female partner and youngest child). The research protocol entailed biological sampling before and after a 20-min behavioral
session during which single men sat alone and fathers interacted with their partner and youngest child. Hormone measures relied upon minimally
invasive techniques (salivary testosterone and cortisol, finger prick blood spot prolactin, urinary oxytocin and vasopressin). Results revealed
significant group differences in average male testosterone levels ( p= 0.006), with post hoc contrasts indicating that visiting fathers had
significantly ( pb0.05) lower testosterone levels than single men. Prolactin profiles also differed significantly across groups ( p= 0.010) whereby
post hoc contrasts showed that prolactin levels of single men declined significantly compared with the flat levels of visiting fathers ( pb0.05). No
group differences in cortisol, oxytocin or vasopressin levels were observed. However, among fathers, vasopressin levels were significantly and
negatively (r=−.431, p= 0.022) correlated with the age of a man's youngest child. These results thus implicate lower testosterone levels as well as
prolactin and vasopressin in human fatherhood. These findings also highlight the importance of sociocultural context in human fatherhood while
exhibiting parallels with existing data on the non-human vertebrate hormonal bases of paternal care.