Search Here

Researchers from the University of California Berkeley may have found a molecular explanation for promiscuity and shifts in the female reproductive system to accommodate sexual freedoms.

By comparing the sexual behaviors of two related species of mice (the California mouse which is known for monogamy and the dear mouse, characterized by long-time sexual promiscuity), experts show that ”sexual habits impact the bacteria hosted by each species as well as the diversity of the genes that control immunity.”

The study explains that monogamy is a very rare trait among mammals, with only five percent of species on earth with the trait, according to a news release. During the evolutionary process, mammals adapt to changes in the physical and social environment.

The study suggests that current social relationship trends have changed us on a molecular level so that we, and women in particular, may adopt promiscuous habits to increase our chances of survival and our offspring's immunity from diseases.

Texas Advanced Computing Center notes that after researchers from the Lacey Lab examined the differences between these two species on the microscopic and molecular levels, they discovered that the lifestyles of the two mice had a direct impact on the bacterial communities that reside within the female reproductive tract; these differences correlate with enhanced diversifying selection on genes related to immunity against bacterial diseases.

According to Scientific American, over 1000 species of bacteria live along and inside the human body, noting that “Bacterial cells in the human body outnumber human cells 10 to one.”

Vaginal bacteria, though most women share common species, can differ depending on an individuals genetic and molecular make-up.

The study found that the promiscuous deer mouse had twice the vaginal bacterial diversity as the monogamous California mouse. Since many bacteria cause sexually transmitted infections (like chlamydia or gonorrhea), he used the diversity of bacteria as a proxy for risk of disease.

Scientists also found hat selective pressures caused by generation after generation of bacterial warfare had fortified the genomes of the promiscuous deer mouse against the array of bacteria it hosts (i.e. sleeping around bolstered bacterial diversity to combat sexually transmitted diseases.”

"The promiscuous mice, by virtue of their sexual system, are in contact with more individuals and are exposed to a lot more bacteria," said Matthew MacManes a post-doctoral fellow at UC Berkley to UCB press. "They need a more robust immune system to fend off all of the bugs that they're exposed to."

The study is published in the May 2012 edition of PLoS One.