Humans harbor a vast and diverse population of microbes that are affected by many factors, including age and genetics, and can in turn influence immunological status. In eLife, Knight and colleagues undertake a comprehensive survey of microbes that inhabit the skin, mouth and gut to determine the influence of cohabitation with family members and dogs. Many patterns emerge; for example, members of the same household share more microbiota with each other than with people from other households, and this overlap is greatest for the skin microbiota. Notably, dog ownership results in more sharing of microbiota among humans, and there is also considerable sharing of microbiota between dogs and humans. Age also has a role, with the greatest changes in gut microbiota occurring within a window during early infancy but the skin microbiota remaining relatively stable with age. A shared environment therefore strongly influences microbiota colonization and this might potentially feed forward into 'tuning' of the immune system.

eLife 2, e00458 (2013)