Scientists have shown that human limbs may have evolved from the same gene structures found in the gills of cartilaginous fish such as sharks, skates and rays. Victorian era German anatomist Karl Gegenbaur proposed the idea a century ago but no fossil evidence came to light to back his claim. The Daily Mail reports: The discovery could shed light on the origin of jawed vertebrates – the group of animals that includes humans. Unlike other fish, cartilaginous fish have a series of skin flaps that protect their gills. These flaps are supported by arches of cartilage, with finger-like appendages called branchial rays attached. In 1878, German anatomist Karl Gegenbaur presented the theory that paired fins and eventually limbs evolved from a structure resembling the gill arch of cartilaginous fish. However, nothing in the fossil record has ever been discovered to support this. Karl Gegenbaur’s sketch from 1870 Now, researchers have reinvestigated Gegenbaur’s ideas using the latest genetic techniques on embryos of the little skate – a fish from the very group that first inspired the controversial theory 138 years ago. They found striking similarities between the genetic mechanism used in the development of its gill arches and those in human [...]