Body Bugs: Why we can’t live without them

Your body is teeming with life. In every nook and cranny, there are miniature ecosystems bursting with bacteria, archaea, fungi, protists and viruses. They form a vital part of your biology, digesting your food, interacting with your immune system and even affecting your mood. Just as different plants and animals live in different habitats on Earth, different species of microbe colonise different parts of your body. The skin on your arms and legs is dry and the temperature is unpredictable, like a desert, so few species are hardy enough to make it their home. But the lining of your gut is warm, wet and full of nutrients, like the tropics, supporting a vast diversity of microscopic life. The microbe communities found in each tiny body ecosystem are known as ‘microbiota’, and their genomes as ‘microbiomes’.

Analysing these miniature ecosystems can be tricky, but techniques have advanced rapidly in recent years. One way to understand body bugs is to take swabs and samples and grow them in petri dishes. But this doesn’t show the whole story. Many microbes that live happily inside our bodies cannot survive on a dish in a lab, so we never see them. Now, with modern gene- sequencing techniques, it’s possible to detect the signatures of these hidden body bugs, and the results are astonishing. As it turns out, we’re more microbe than human, and our microbiomes are more unique than our genes.