Unlike humans, lemur dads receive a boost in male hormones from being active parents.
In humans, when men marry and have children, their levels of male sex hormones often decline. Scientists think this could be because androgens, such as testosterone, are commonly associated with aggression and mate competition, and could therefore impede dads' abilities to bond with and care for their children.
Yet research on another primate – the red-bellied lemur – suggests a different story.
Red-bellied lemurs live in close-knit groups of three to five – one adult female, one adult male and their offspring. The male and female reproduce no more than once a year.
Like humans, lemurs engage in allomaternal care, meaning others besides the biological mother participate in caring for offspring. In lemur families, fathers and siblings may help out, while in humans, caregiving responsibilities may also extend to other family members, friends, teachers, babysitters and so on.
A new study has shown that male lemurs' androgen levels actually increase as they engage in child care behaviours. Anthropologists Stacey Tecot, one of the authors of the new study, suspects the spike may instead be linked instead to protective parenting.
“Fathers go through hormonal changes, as well as mothers, that can help facilitate care of offspring, and elevated androgen levels don’t necessarily inhibit infant care,” Tecot said. “They could actually facilitate it.”