After sexual encounters, we leave behind a unique microbial signature from our genital areas on our partners. This ‘sexome’ could have forensic applications in identifying perpetrators of sexual assault, even when no semen is present.
Uncovering the Secrets of the ‘Sexome’
Researchers have confirmed that both men and women harbor distinct populations of bacteria in their genital regions, dubbed the ‘sexome’. By analyzing the microbial makeup before and after sexual intercourse in 12 monogamous heterosexual couples, they discovered that each person’s unique bacterial signature could be detected in their partner’s genital sample following sex. This transfer occurred even when condoms were used, though condoms seemed to primarily facilitate transfer from the female to the male partner.
A Forensic Breakthrough? Tracing Sexual Encounters
Traditional forensic examinations in sexual assault cases often rely on detecting the perpetrator’s semen as evidence of intercourse. However, in many cases no semen is found, such as when condoms are used. The ability to trace the transfer of genital microbes between partners could provide a new avenue for identifying perpetrators. ‘When a condom was used, the majority of transfer occurred from the female to the male,’ says researcher Ruby Dixon. ‘This shows promise for testing a perpetrator post-assault, even when a condom was used.’
The Evolving Mysteries of Our Genital Microbiomes
Just as our gut harbors a diverse community of microbes, the vagina and penis also host their own unique microbial ecosystems. These ‘sexomes’ are relatively stable but can change based on factors like menstruation. Over time, the microbes evolve distinct genetic signatures, much like animal populations diverging on isolated islands. ‘It’s a bit like a mouse on an island,’ explains researcher Brendan Chapman. ‘Two islands might have the same mouse species, but as they breed and evolve, the two islands develop genetically different mice.’ This rapid microbial evolution allows the ‘sexome’ to develop identifying fingerprints for individuals.
