The cover illustration is inspired by the original painting ‘Our Self-Portrait: the HumanMicrobiome’ by scientific artist Joana Ricou (http://go.nature.com/xrdb9o). The Human Microbiome Project (HMP), supported by the National Institutes of Health Common Fund, has the goal of characterizing the microbial communities that inhabit and interact with the human body in sickness and in health. In two Articles in this issue of Nature, the HMP Consortium presents the first population-scale details of the organismal and functional composition of the microbiota across five main body areas. An associated News & Views discusses these initial results — which, along with those of a series of co-publications, already constitute the most extensive catalogue of organisms and genes related to the human microbiome yet published — and highlights some of the major questions that the project will tackle in the next few years. (Cover graphics: Steven H. Lee/ Studio Graphiko.)
I've been really interested in the developing research about the human body as a super-organism or an ecossystem, where non-human cells outnumber human cells 10-to-1. The notion that we have bacteria in our bodies is not unfamiliar, although it's mostly linked to things that make us sick and things that live in our intestine and help digest our food. But it's not just bacteria, there are fungus, mites, algae and other kinds of eukaryotes. And a lot of these are essential to our health and well-being, and the extent that they influence how we feel, or the extent to which they are us, too. They also connect us dynamically to our environment, as we exchange these populations constantly. This piece was the beginning of an exploration of the identity of our other selves - the Multitudes series.