how many organisms are in a human body
As of 2014, it was often reported in popular media and in the scientific literature that there are about 10 times as many microbial cells in the human body as there are human cells; this figure was based on estimates that the human microbiome includes around 100 trillion bacterial cells and that an adult human typically has around 10 trillion human cells. In 2014, the American Academy of Microbiology published a FAQ that emphasized that the number of microbial cells and the number of human cells are both estimates, and noted that recent research had arrived at a new estimate of the number of human cells -- approximately 37.2 trillion, meaning that the ratio of microbial-to-human cells, if the original estimate of 100 trillion bacterial cells is correct, is closer to 3: 1. In 2016, another group published a new estimate of the ratio being roughly 1: 1 (1.3: 1, with "an uncertainty of 25% and a variation of 53% over the population of standard 70-kg males").