Every animal on the planet carries with it an astonishingly diverse microbial zoo – millions of invisible organisms that thrive on the skin and in the gut. They play an important role in health and disease and may also shape human emotions and behaviour. Viruses may stimulate aggression, parasites can trigger suicide and bacteria can block fear responses. The evidence for our interaction with microbes may even make us want to re-evaluate the concept of free-will.
Science