Andrew Anthony sent his stool off to have its bacteria sequenced. In the future, such techniques could help assess our susceptibility to conditions from diabetes, Parkinson's and Alzheimer's to autism, depression and cancer
We are all familiar with "gut feelings", "gut reactions" and "gut instincts", but how much do we really know or care about our guts? As we become increasingly more aware of what we put in our stomachs, it's striking how ignorant we remain of what takes place in our intestines. And it turns out there is an awful lot going on down there.
Microbiologists have made some startling advances in revealing our innermost secrets. It turns out that there is a complex ecosystem deep within us that is home to a fantastic diversity of life – of which very little belongs to our species.
For most of us, suspicious of foreign bodies, it's a struggle to comprehend that at our very core we are less than – or rather much more than – human. But, the fact is, there are about 100 trillion organisms living in the gut. If you put them all together they would be about the size of a football. In terms of cells, the microbial kind outnumber their human counterparts by about three to one. And in terms of genes, the microbial advantage is more like 300 to one.
That means there is a tremendous amount of us that is not, so to speak, us. This raises a whole range of interesting philosophical and anatomical questions, of which the most urgent might be: should we be worried?