Bacteria May Influence Fear in Babies The microbes that call the human gastrointestinal tract home are with us since birth (or even earlier) and seem to have a powerful influence on our developmental, physical, and mental health. Researchers are learning more about the complex interplay between gut microbes and the genes they carry and express, and human physiology. The gut microbiome is even directly connected to the brain. Scientists have now found evidence that suggests the gut microbes in an infant have an impact on how those babies perceive danger, in non-social situations. In some cases, the fear response in infants is related to their future mental health. Reporting in