Microbiome A microbiome is "the ecological community of commensal, symbiotic, and pathogenic microorganisms that literally share our body space." Joshua Lederberg coined the term, arguing the importance of microorganisms inhabiting the human body in health and disease. Many scientific articles distinguish "microbiome" and "microbiota" to describe either the collective genomes of the microorganisms that reside in an environmental niche or the microorganisms themselves, respectively. The human body contains over 10 times more microbial cells than human cells, although the entire microbiome only weighs about 200 grams (7.1 oz), with some weight estimates ranging as high as 3 pounds (approximately 48 ounces or 1,400 grams). Some[who?] regard it as a "newly discovered organ" since its existence was not generally recognized until the late 1990s and it is understood[by whom?] to have potentially overwhelming impact on human health. Modern techniques for sequencing DNA have enabled researchers to find the majority of these microbes, since the majority of them cannot be cultured in a lab using current techniques. The human microbiome may have a role in auto-immune diseases like diabetes, rheumatoid arthritis, muscular dystrophy, multiple sclerosis, fibromyalgia, and perhaps some cancers. A poor mix of microbes in the gut may also aggravate common obesity. Since some of the microbes in our body can modify the production of neurotransmitters known to be found in the brain, we may also find some relief for schizophrenia, depression, bipolar disorder and other neuro-chemical imbalances. Researchers have started to characterize microbiomes in many non-human environments as well, including soil, seawater and freshwater systems. It is believed[by whom?] that endosymbiosis originally gave rise to more complex organisms, and continued to play a fundamental role in guiding their evolution and expansion into new niches. The microbes being discussed are generally non-pathogenic (they do not cause disease unless they grow abnormally); they exist in harmony and symbiotically with their hosts.