Bacterial DNA a key component of vertebrate vision

An ancient gene that our ancestors snatched from bacteria some 500 million years ago became a key component in all vertebrates’ vision. The gene encodes a protein that shuttles light-reactive molecules between cells and is found in all vertebrates — but not in invertebrates. It most closely resembles a class of bacterial genes that encode protein-recycling proteins. Bacteria are known to swap genes, and vertebrates can also incorporate microbial DNA.