Tens of millions of bacteria are crawling on your skin and squirming in your gut and in your mouth.

Thank goodness! Your microbiome — that’s the collection of tens of thousands of species crawling through you — plays a role in training the immune system, and some skin bacteria even helps prevent acne. But scientists are only beginning to understand the human microbiome. That’s where the Emerald City Roller Girls come in.

Since roller derby involves frequent and forceful skin-to-skin contact, former derby-er and current biology professor Jessica Green (aka “Thumper Biscuit”) suggested it would be a useful way to look at the skin’s microbiome. Scientists at the UO took bacteria samples from the shoulders of a Eugene roller girls team and their out-of-state opponents before, during and after a bout.

James Meadow, lead author of the study, says they got their first result before play even started: Teammates shared a unique team microbiome. “If we had picked out a player at random, I could tell you which team she played for just by swabbing the bacteria on her upper arm,” he says. “It got more and more difficult as they play against each other to tell them apart because they’d been sharing microbes as the bout went on.”

Meadow says teammates might share a microbiome for any number of reasons, including climate (the other teams were from the San Francisco Bay Area and Washington D.C.), frequent contact and even, possibly, a long van ride to the bout. He says learning that roller girls have a team microbiome is important because new technology means scientists are just starting to really understand healthy bacteria. “A lot of what we know about the microbiome is from sick people sharing pathogens,” he says. “The vast majority of the microbes on the body are really good for us.”

Now the scientists are working with a filmmaker to create a documentary, Talk Derby To Me. Check out the trailer at talkderbytomefilm.tumblr.com