title: On the evolutionary advantage of multi-cusped teeth.
abstract: A hallmark of mammalian evolution is a progressive complexity in postcanine tooth morphology. However, the driving force for this complexity remains unclear: whether to expand the versatility in diet source, or to bolster tooth structural integrity. In this study, we take a quantitative approach to this question by examining the roles of number, position and height of multiple cusps in determining sustainable bite forces. Our approach is to use an extended finite-element methodology with due provision for step-by-step growth of an embedded crack to determine how fracture progresses with increasing occlusal load. We argue that multi-cusp postcanine teeth are well configured to withstand high bite forces provided that multiple cusps are contacted simultaneously to share the load. However, contact on a single near-wall cusp diminishes the strength. Location of the load points and cusp height, rather than cusp number or radius, are principal governing factors. Given these findings, we conclude that while complex tooth structures can enhance durability, increases in cusp number are more likely to be driven by the demands of food manipulation. Structural integrity of complex teeth is maintained when individual cusps remain sufficiently distant from the side walls and do not become excessively tall relative to tooth width.
authors: Department of Biology, Saint Michael's College, Colchester, VT 05439, USA paulconstantino@gmail.com.
authors: Paul J
authors: 0000-0003-3397-7961
authors: PJ
authors: Constantino
authors: School of Mechanical and Chemical Engineering, University of Western Australia, Crawley, Western Australia 6009, Australia.
authors: Mark B
authors: MB
authors: Bush
authors: School of Mechanical and Chemical Engineering, University of Western Australia, Crawley, Western Australia 6009, Australia.
authors: Amir
authors: A
authors: Barani
authors: Materials Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
authors: Brian R
authors: BR
authors: Lawn
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001732:Bite Force; D008322:Mammals / Q000033:anatomy & histology / Q000502:physiology*; D014070:Tooth / Q000033:anatomy & histology / Q000502:physiology*
keywords: contact mechanics; dental evolution; dental morphology; fracture; mammalian origins