Abstract

The development of just two generations of teeth throughout a mammal’s life limits the functional longevity of the dentition. To prolong this functional lifespan, various strategies have evolved, including changes of the sequence in which the teeth erupt. In particular, ‘Schultz’s rule’ predicts that replacement teeth (incisors, canines, and remolars) tend to erupt earlier than posterior molars in slow-growing mammals with a ‘slow’ life history (e.g. humans), compared to mammals with a ‘fast’ life history (e.g., lemurs). Although Schultz’s rule has been investigated in some clades, its universal applicability and influencing factors remain to be tested. Such investigations are especially important regarding the study of life history in extinct taxa. In the studies I am going to present here, we set out to investigate if Schultz’s rule extends to the entire mammalian clade. In addition to wild mammalian species, we also used domesticated mammals as a model for evolutionary changes, as domestication has led to an accelerated life-history. Our results show that evolution of tooth eruption sequences does correlate with life history, but is also controlled by a range of other factors (e.g., jaw growth).