We are only 10 percent human. For each cell that forms that vessel called the body, there are nine others that, like true impostors, scrounge a passage. We are not only made of flesh and blood, muscle and bone, epidermis and brain, but also of fungi and bacteria.Throughout our lives we host so many microbes that their weight would be equivalent to that of five African elephants, because in in reality we are not individuals but colonies. For...