The evolution of the anus may have driven the body plan of all advanced animals, including humansMattLphotography / AlamyThe anus is a wildly successful innovation, but how did it evolve? A genetic analysis suggests it probably began as an opening used to release sperm that later fused with the gut an example of evolution repurposing structures.Once a hole is there, you can use it for other things, says Andreas Hejnol at the University of Bergen in Norway.It is thought that early animals evolved