Publication Date
3-10-1970
Series Number
143
Abstract
Analyses of wear characteristics on the teeth of a young adult male baboon, a male native human from New Guinea and a male Caucasian from New Zealand are made, and their inseparable relationship to behavior emphasized. These characteristics provide evidence of the evolution of precise anatomical and innate behavioral tooth-grinding mechanisms specific to the production of sharp teeth. Although the teeth on eruption have some degree of morphological sharpness, the tooth-grinding behavior perfects this sharpness and subsequently maintains it throughout the functional life of the teeth. The male baboon, used here as broadly representative of man's non-hominid relatives and ancestors, has a specialized, sickle-like, vertically oriented upper canine, sharpened specifically as a slashing weapon. The lower anterior premolars are the honing tools which grind against the upper canines in a motion opposite to that of the masticatory stroke. These premolars are noticeably specialized for this tooth-to-tooth grinding action by their enlarged buccal crown-faces, thickened enamel gingival extensions, and by paired roots placed perpendicular to the "whetstone" faces. In contrast, man's short-canine condition has evolved to provide a specialized, horizontally sharp shearing device. The continuous rows of even, constantly sharpened teeth, vertically oriented and firmly anchored in jaws which provide greater force at the biting teeth, give man the capacity for powerful, lethal, "segmentive" biting. Thus man's dentition is seen not as "generalized", and certainly not as "regressed" or "weakened", but as highly specialized. The significance of the short-canine condition (currently regarded as a diagnostic feature of hominids) is not that man has become biologically defenseless, but that the hominid dental mechanism has harnessed attritional wear to provide a more stable and durably functional weapon. It is concluded that tooth-sharpening and related phenomena are evidence of innate behavior related to a specialized, viable, biological weapon in Homo sapiens, and because this weapon — the teeth — is the primary one and has been overlooked it emphasizes a corollary: intraspecies use of the teeth is strictly controlled by genetical determinants, whereas such control of the secondary weapon —the hand — is slight.