ISTOCK, PRETTY VECTORS
Our relationship with microbes begins early in life. As an infant passes from the womb to the world through her mother’s birth canal, she is exposed to a multitude of bacteria and fungi. Although a handful of studies now suggest that the womb may not be sterile as many once believed, microbes are much more abundant in the outside world.
How our bodies learn to peacefully coexist with cells that are not our own is still unclear. Afterall, we spend most of our lives fighting off microbial invaders. “Once you’re born, you’re assaulted by billions of bacteria, so if the babies’ [immune systems] responded in the appropriate adult manner, they would just be auto-inflammatory bundles,” says Grace Aldrovandi, a professor of pediatrics at the University ...
