Human as Spaceship.

You are a spaceship soaring through the universe. So is your dog . We all carry with us trillions of microorganisms as we go through life. These multitudes of bacteria , fungi , and archaea have different DNA than you. Collectively called your microbiome, your shipmates outnumber your own cells. Your crew members form communities , help digest food , engage in battles against intruders, and sometimes commute on a liquid superhighway from one end of your body to the other. Much of what your microbiome does, however, remains unknown . You are the captain , but being nice to your crew may allow you to explore more of your local cosmos .