The Human Microbiome
The human body is home to trillions of microoganisms, including bacteria, viruses, and fungi. In a healthy adult, this microbiota collectively has a biomass equal to the human brain, and includes thousands of distinct species that have co-evolved with humans and are thought to influence human health and disease. These species, their combined genomes, and the biological interactions they share with each other and their human hosts combine to make up the "human microbiome."