The Human Microbiome Project (HMP) has begun to show the diversity of the microbial ecosystems on and in each of us.49 Initiated by the NIH in 2007, this ambitious project uses high throughput sequencing to identify the array of microbes present in human samples. At birth we become dynamic hosts to an eventual population of over a trillion organisms, and until the inception of the HMP, we had only a rudimentary understanding of what organisms were even present, and their relative abundance, since many organisms cannot be cultured outside of the human host.50,51 This complex ecosystem of organisms on and in us is increasingly recognized as a major contributor to many processes in the healthy human and, when either host or microbial factors go astray, disease.
