Question: what does shubin call the regulatory gene that controls the body segments

title: Evolutionary developmental biology
text: Using such a technique , in 1994 Walter Gehring found that the pax - 6 gene , vital for forming the eyes of fruit flies , exactly matches an eye - forming gene in mice and humans . The same gene was quickly found in many other groups of animals , such as squid , a cephalopod mollusc . Biologists including Ernst Mayr had believed that eyes had arisen in the animal kingdom at least 40 times , as the anatomy of different types of eye varies widely . For example , the fruit fly 's compound eye is made of hundreds of small lensed structures ( ommatidia ) ; the human eye has a blind spot where the optic nerve enters the eye , and the nerve fibres run over the surface of the retina , so light has to pass through a layer of nerve fibres before reaching the detector cells in the retina , so the structure is effectively `` upside - down '' ; in contrast , the cephalopod eye has the retina , then a layer of nerve fibres , then the wall of the eye `` the right way around '' . The evidence of pax - 6 , however , was that the same genes controlled the development of the eyes of all these animals , suggesting that they all evolved from a common ancestor . Ancient genes had been conserved through millions of years of evolution to create dissimilar structures for similar functions , demonstrating deep homology between structures once thought to be purely analogous . This has caused a radical revision of the meaning of homology in evolutionary biology .