Dental Allometry in Mammals: A Retrospective

Abstract

Kleiber suggested that mammalian metabolic rate scales with body mass at Mb3/4. Bigger animals use relatively less energy. Gould reasoned that teeth should scale the same way given caloric need. In many cases though, cheek tooth occlusal area increases isometrically, one-to-one with body mass (i.e., Mb2/3). Fortelius reconciled the discrepancy by noting that larger mammals also chew slower, so a given amount of food per bite but few bites per unit time could still mean metabolic scaling of energy consumed in a day. Here I revisit dental allometry, referencing new studies of tooth size, muscle mass, chewing rate, and food fracture scaling. Early predictions have held up reasonably well through the decades, though many more factors involved have emerged. These can be difficult to parse for intepreting deviations from expected tooth size in fossil mammals, including early hominins. Still, relative tooth size variation can help us generate dietary hypotheses.