If the genes of a tiny, bumless invertebrate are anything to go by, our anuses might be repurposed sperm chutes. A new study suggests instead of releasing waste, the first anal orifice was an exit hatch for male sex cells which was given a new task. Researchers from the University of Bergen in Norway investigated the genetics of xenacoelomorphs; distant relatives of flatworms that have a cul-de-sac for a gut. Despite this lack of a dedicated poop-hole, xenacoelomorphs use some of the same genes we use to turn our digestive system into a tube, only to create a genital...