Most people are familiar with the role of DNA: A set of genetic instructions on how a particular living organism should function. This nucleic acid has been widely explored as a way to identify individuals, define illnesses or hereditary diseases and contribute to behavior, among many other clues about an individual. However, there may be another complex feature of human anatomy that influences many surprising aspects of human physiology, immunity and evolution: gut flora.
Scientists have known for decades that the human intestinal tract is home to an abundance of diverse bacteria. This microbial rainforest is introduced incrementally to infants as they grow—primarily from their mothers during birth and breastfeeding and from everyday encounters. Many of these microbes aid in digestion and fight off pathogens, but until recently, researchers were not certain if phages, viruses that infect bacteria, were also present in the human gut.