Brain Chemistry Shift Made Some Female Lemurs Less Aggressive, Study Finds.

In the world of lemurs, female dominance is a well-documented behavior, often enforced with surprising aggression. But a recent study from Duke University suggests that some lemur species have evolved a more cooperative approach between the sexes, potentially driven by neurological changes in their brains.

Among primates, lemurs stand out for their matriarchal societies. In several species, females assert control over males, securing the best food and resting spots and enforcing their dominance through physical aggression. This behavior, researchers note, often occurs without provocation—more a reminder of who’s in charge than a defensive act.

However, not all lemur societies function this way. Within the genus Eulemur, which includes closely related species, researchers have identified a shift in social dynamics in some species that emerged within the past million years. These groups, including the collared lemurs, demonstrate a more balanced interaction between males and females, where power and access to resources are shared more equally.

To understand the roots of this social evolution, researchers examined brain tissues from seven Eulemur species—samples preserved at the Duke Lemur Center after the animals died of natural causes. Using a technique called autoradiography, the team focused on mapping the presence of oxytocin receptors in the brain. Oxytocin, often referred to as the “love hormone,” is known for its role in social bonding and trust.

The analysis revealed a significant difference: species with more egalitarian social structures had a greater density of oxytocin receptors in their brains, particularly in the amygdala. This region is associated with emotional regulation, including fear and aggression. The finding applied to both male and female lemurs, indicating a general reduction in aggression rather than a change specific to one sex.

According to senior author Christine Drea, professor of evolutionary anthropology at Duke, this suggests that these species didn’t reach social parity by males becoming more dominant, but rather through a mutual softening of behavior.

Lead author Allie Schrock, who completed her Ph.D. in Drea’s lab, added that the presence of more oxytocin receptors appears to allow for increased social harmony. The implications of the study extend beyond lemurs, as oxytocin signaling has been linked to various human behaviors and conditions, including aggression, personality disorders, and autism.

The research team plans to expand their investigation to explore how hormone receptor distribution relates to other social behaviors in lemurs, such as whether they tend to live alone or in groups. As Schrock notes, “There’s still much to learn from lemurs about how the brain shapes behavior.”

Source:https://phys.org/news/2025-04-lemur-brains-girls-nice.html

This is non-financial/medical advice and made using AI so could be wrong.