You could be sitting alone and still be completely outnumbered for your body is home to trillions upon trillions of tiny passengers – bacteria. Your body is made up of around ten trillion cells, but you harbour a hundred trillion bacteria. For every gene in your genome, there are 100 bacterial ones. This is your ‘microbiome’ and it has a huge impact on your health, your ability to digest food and more. We, in turn, affect them. Everything from the food we eat to the way we’re born influences the species of bacteria that take up residence in our bodies.

This slideshow is a tour through this “universe of us”. Every slide has links to previous pieces that I’ve written