Sexual Aggression in Non-Human Mammals Might Be Costly for Females, Study Shows

Male mammals rarely take care of their offspring which led researchers to believe that sexual aggression among non-human mammals is intense. Sexual aggression is seen to be an act of male aggression towards its mate.

But since the measurements and interpretations of the behaviors of male non-human mammals, such as sexual aggression and sexual coercion, are very complex, the researchers preferred the term sexual disturbance in describing these behaviors towards females during mating. It was also found out that the same can be costly for females.

According to the findings of the study, published in the journal Mammal Review, sexual disturbance during the pericopulatory period might inflict harm and cause mother-offspring separation. This study is a review of published studies about the behavior of male non-human mammals.

Females response to male sexual disturbance

The sexual disturbance was found to be frequently happening in four out of 32 mammalian orders that the study author, Marcelo H. Cassini, Ph.D., of the Laboratorio de Biología del Comportamiento, have examined.

These species are Primates, Artiodactyla, Carnivora, and Cetacea, which all have species that are considered to engage in polygyny, wherein males mate with multiple females. The study found that the most common response by females to sexual disturbance is by grouping around the dominant male, Phys.org reported.

The most common expression of sexual conflict during the pericopulation period was seen in behaviors associated with female retention attempts that cause minor harm, the study showed.

Dr. Cassini said that additional research is needed to find out if sexual disturbance has any effect on the reproductive success of males and females. He added that this review of studies has shown that sexual aggression is a rare behavior among thousands of species of mammals.

Sex and aggression circuits in animal brains tend to overlap in males and not in females

Sexual aggression among male non-human mammals may be explained by the overlapping of brain circuits in males that is not present in female animals. A study from 2017 suggests that the brain structures that control sex and aggression in mice are wired differently in females and males.

Although the control of aggressive behavior in both male and female resides in the same brain region. the researchers found that certain groups of brain cells are organized differently. Brain circuits that encouraged sex and aggression in males overlapped with each other, unlike in females which are found in separate groups.

"Our study furthers our understanding of how these behaviors are organized differently in female and male mice brains," according to Dayu Lin, the study senior investigator and an assistant professor at the Neuroscience Institute at NYU Langone Health.

Lin added that having a detailed breakdown of how the brain functions is a significant help in attempting to develop a medicine that suppresses extreme aggression in the brain. She also said that studies on female aggression are usually not discussed because males tend to be more aggressive than females.