The Human Microbiome Project
At 2013-09-28 04:05:12 AM | 176
Before the Human Genome Project was completed, some researchers predicted that 100,000 genes would be found. So, many were surprised and perhaps humbled by the announcement that the human genome contains only 20,000 protein-coding genes, not much different from the fruitfly genome. However, if the view of what constitutes a human is extended, then it is clear that 100,000 genes is probably an underestimate. The microorganisms that live inside and on humans (known as the microbiota) are estimated to outnumber human somatic and germ cells by a factor of ten. Together, the genomes of these microbial symbionts (collectively defined as the microbiome) provide traits that humans did not need to evolve on their own1. If humans are thought of as a composite of microbial and human cells, the human genetic landscape as an aggregate of the genes in the human genome and the microbiome, and human metabolic features as a blend of human and microbial traits, then the picture that emerges is one of a human 'supra-organism'.