For your community of microbes – your ‘microbiome’ – your body is a planet. Some prefer the temperate forest of your scalp, some the arid plains of your forearm, some the tropical forest of your crotch or armpit. Your gut (which if unfolded would occupy an area of 32 square metres), ears, toes, mouth, eyes, skin and every surface, passage and cavity you possess teem with bacteria and fungi. You carry around more microbes than your ‘own’ cells. There are more bacteria in your gut than stars in our galaxy.18
