Turns out, when you shacked up with your partner – his bacteria moved in, too.
A new study from the University of Waterloo found that couples who live together significantly influence the microbial communities on each other’s skin.
Yep, we’re talking all the microorganisms that live on the surface of your skin, including bacteria. Or, as the study authors put it: “human skin is inhabited by a diverse community of bacteria, archaea, fungi, protozoans, and arthropods.” Can’t. Even.
The study says that “between one million and one billion microorganisms inhabit each square centimeter of skin,” so they set out to test if these organisms were influenced by the partner we lived with.
The researchers analysed 330 skin swabs taken from 17 sites on the study participants, including nostrils, armpits, navel and eyelids. They found the couples' skin microbiomes were most similar on their feet.
“In hindsight, it makes sense,” says senior study author Josh Neufeld. “You shower and walk on the same floor barefoot. This process likely serves as a form of microbial exchange with your partner, and also with your home itself.”
In fact, the scientists found that computer algorithms could figure out which couples lived together with 86% accuracy based on their skin microbiomes alone. Sexy.
However, microbial communities on the inner thigh were actually more similar among people of the same sex, rather than between partners. As a result, the computer algorithm could figure out which samples were from men and which were from women with 100% accuracy.
So what’s the point? Research like this helps scientists figure out how the microrganisms that live on our skin adapt over time - to where we live and who we live with. “Ultimately what we're trying to learn is whether skin microorganisms have co-evolved with their hosts over time,” says Neufeld.