We are not alone. We are home to a trillion cells that are not our own, but are very much the making of us. Both on us and inside us live bacteria, viruses, protozoans, fungi, worms, lice and mites that we carry throughout our lives. To say that we are in a minority in our own body is an understatement. Our ‘private wildlife’ keeps us healthy, sometimes makes us ill and even changes our behaviour. Our journey of discovery through the natural history of bugs begins with the skin. We are all covered in resident bacteria providing our first line of defence against invading pathogens. Even before our immune system is activated, this protective layer of bacteria will fight off alien species. But if the skin is compromised, these invaders can threaten our lives.
Our health, body shape, mood and even our evolution are determined by the unseen life forms that swarm throughout our bodies. There are worms in your bowels, bacteria in your mouth, fungi in your lungs and even viruses in your DNA. The combined genetic information of all these bugs is more than 150 times greater than our own genes. Their cells outnumber our own by 10 to 1. This collective menagerie is called the microbiome, and in a very real sense, it is the making of us all. Though they have evolved with us over millennia, in recent years we have been drastically changing our relationship with our internal microbes, bombing them with antibiotics and an unhealthy diet. The consequence of this war on our bugs is an epidemic of disease. This episode looks at the battleground within our bodies and the remarkable new science that is changing our views about health and disease.