The trillions of microbes living on and inside the human body are an important part of who we are, from mediating all of our interactions with the environment to determining our cancer risk and influencing who we fall for. And scientists are only just beginning to decipher the species of bugs we share our lives with, and how they shape us. In the final part of this Science Weekly mini-series, Ian Sample meets Julie Thornton, academic director of the Centre for Skin Sciences and professor in cutaneous biology at the university of Bradford. Julie tells Ian how the skin microbiome varies across our bodies, how it helps with everything from wound healing to immunity, and how we can protect it from the disruptive impact of modern life.. Help support our independent journalism at theguardian.com/sciencepod