"Mice fed a broth rich in this particular microorganism become more adventurous and show fewer signs of stress. The bacteria don’t just give them a healthier gut but also a healthier brain, an indication that who we are is intimately shaped by what lives inside our body. Such findings also suggest that the enteric nervous system, our “second brain,” may have as much influence over our behavior as does the stuff up top.
Given that the human microbiome is at this point a vast yet mostly uncharted territory, the fact that this is territory in which medicine through the use of antibiotics has engaged in open warfare for much of the last century, is all the more reason to think about what we are and consider the likelihood that in a rampage to kill our enemies we have also been destroying our selves."
What you are is what eats — War in Context