Identification of Reptilian Genes Encoding Hair Keratin-Like Proteins Suggests a New Scenario for the Evolutionary Origin of Hair

The study identified genes in reptiles, specifically in chickens and the green anole lizard, that encoded proteins similar to mammalian hair keratins, suggesting that the genetic basis for hair might have predated mammals. This challenged the previous belief that hair keratins were exclusive to mammals, proposing instead that these proteins were inherited from a common ancestor of mammals and sauropsids. The research found six putative orthologues of mammalian hair keratins in the anole genome and one in chicken, indicating that the ability to form hard keratin structures may have originated from a common ancestor, necessitating a revision of the evolutionary history of hair.