The lens growth was studied in a number of curves representing 16 mammalian species. Emphasis was placed on determining the length of the lens development stage. All the lens curves studied went through a growth crisis: It is a period of apparent growth slowing down, lasting linear during the resting lifespan (adult stage). The growth crisis occurred at a length that was characteristic for the species and was shown to be directly correlated with the species maximum lifespan potential. These results may indicate the prevalence of a common functional basis regulating the lens growth and thus operating in the longevity of mammalian species.