Axolotls exhibit neoteny, meaning that they reach sexual maturity without undergoing metamorphosis. The syndrome is characterized by decelerated maturation (neoteny), incomplete morphogenesis (vestigia) and atavisms. Many prominent evolutionary theorists propose that neoteny has been a key feature in human evolution. Some evolutionary theorists have proposed that neoteny was a key feature in human evolution. Neoteny is not a ubiquitous trait of the human phenotype. Neoteny in humans is the retention of juvenile features well into adulthood. Neoteny is seen in domesticated animals such as dogs and mice. Neoteny of the human body is indicated by glabrousness (hairless body). It was suggested that subcellular neoteny could explain why sperm cells have atypical centrioles. Many lapdogs are bred to retain puppy-like traits (neoteny) such as folded ears. From the point of view of the mimicker, the neoteny expression signals appeasement or submissiveness. Glabrousness is a trait that may be associated with neoteny. This discovery was the starting point of research about neoteny. However, some studies may suggest the opposite of this idea of neoteny being beneficial. These conditions are thought to favor neoteny.