8 Things You Didn't Know About Your Penis
Sensitivity, pleasure, size, and other surprising facts.
7. Your Penis Is a Habitat continued...
After circumcision, there were fewer kinds of bacteria on the men's penises. Many of the kinds of bacteria found to be less common or absent after circumcision were anaerobic -- meaning that they don't need oxygen to grow.
The inner fold of the foreskin is a mucous membrane, like the inside of a person's eyelids. Price says that certain anaerobic bacteria thrive in that environment but not on dry skin.
"I liken it to clear-cutting a forest," Price says. "You're going to get a lot more sunlight, and you're going to drastically change the environment."
The study was done in Uganda, and all of the men studied were Ugandan.
Liu says that she would expect to see some variation in the kinds of bacteria found on men in other parts of the world. "I think there is certainly variety even among the Ugandan men themselves," she says.
But the researchers are less interested in surveying the penile bacteria of the world than in understanding changes brought about by circumcision.
Their research could help explain why circumcision has been linked to a lower risk of getting HIV. One theory is the anaerobic bacteria may prompt the immune system to respond in a way that makes cells more vulnerable to HIV infection.
8. Most Men Aren't Circumcised
Worldwide, approximately 30% of males aged 15 and older are circumcised, according to a 2007 report from the World Health Organization (WHO) and UNAIDS.
Rates vary greatly depending upon religion and nationality, the report states. Almost all Jewish and Muslim males in the world have circumcised penises, and together they account for almost 70% of all circumcised males globally.
Some research shows that there may be health benefits from circumcision. For instance, circumcised men may be less likely to pass sexually transmitted diseases to their female partners or to develop penile cancer.
A 2012 policy statement by the American Academy of Pediatrics (AAP) affirms, “Evaluation of current evidence indicates that the health benefits of newborn male circumcision outweigh the risks and that the procedure’s benefits justify access to this procedure for families who choose it. Specific benefits identified included prevention of urinary tract infections, penile cancer, and transmission of some sexually transmitted infections, including HIV.” This statement has also been endorsed by the American College of Obstetricians and Gynecologists.
In recent years, several studies have shown that circumcised men are less likely to be infected with HIV. The WHO and UNAIDS now recommend male circumcision as an HIV prevention measure. "There is compelling evidence that male circumcision reduces the risk of heterosexually acquired HIV infection in men by approximately 60%," the WHO states.