People Are Human-Bacteria Hybrid ?

Most of the cells in your body are not your own, nor are they even human. They are bacterial. From the invisible strands of fungi waiting to sprout between our toes, to the kilogram of bacterial matter in our guts, we are best viewed as walking 'superorganisms,' highly complex conglomerations of human, fungal, bacterial and viral cells.

That's the view of scientists at Imperial College London who published a paper in Nature Biotechnology Oct. 6 describing how these microbes interact with the body. Understanding the workings of the superorganism, they say, is crucial to the development of personalized medicine and health care in the future because individuals can have very different responses to drugs, depending on their microbial fauna.

The scientists concentrated on bacteria. More than 500 different species of bacteria exist in our bodies, making up more than 100 trillion cells. Because our bodies are made of only some several trillion human cells, we are somewhat outnumbered by the aliens. It follows that most of the genes in our bodies are from bacteria, too.

Luckily for us, the bacteria are on the whole commensal, sharing our food but doing no real harm. (The word derives from the Latin meaning to share a table for dinner.) In fact, they are often beneficial: Our commensal bacteria protect us from potentially dangerous infections. They do this through close interaction with our immune systems.

'We have known for some time that many diseases are influenced by a variety of factors, including both genetics and environment, but the concept of this superorganism could have a huge impact on our understanding of disease processes,' said Jeremy Nicholson, a professor of biological chemistry at Imperial College and leader of the study. He believes the approach could apply to research on insulin-resistance, heart disease, some cancers and perhaps even some neurological diseases.

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