Our microbes, ourselves: Billions of bacteria within, essential for immune function, are ours alone

Our microbes, ourselves: Billions of bacteria within, essential for immune function, are ours alone: Gut bacteria's key role in immunity is tuned to the host species, suggesting that the superabundant microbes lining our digestive tract are ultimately our evolutionary partners. This study, the first to demonstrate that microbes are specific to their host species, also sheds light on what's called the hygiene hypothesis.