Genetic Regulation of Amelogenesis and Implications for Hominin Ancestors

Histological analysis of mammalian enamel reveals a characteristic pattern of development that has been linked to daily growth increments. This daily growth has contributed to interpretations of the biology of early hominins. Recent studies have attempted to identify a molecular mechanism to explain this daily enamel growth. These data suggest that the circadian clock is a likely modulator of genetic activity as enamel forms. In the present study, the process of enamel development is reviewed together with new data on how the circadian clock modulates this process. A hypothesis is proposed to explain possible physiological functions of the enamel clock in post-mitotic ameloblast cells. This information is used to interpret how modifications of the activity of the enamel clock influenced hominin evolution.