Discriminant Analysis of Rocker Jaws from Mokapu, Oahu

Abstract

<p>The major emphasis of the thesis is a study of a particular morphological feature of the mandible known as "rocker jaw". The trait is a characteristic of Hawaiian populations. The framework of the study is the multivariate analysis of the characteristic to determine whether there are associated physical characteristics on the mandible. Also included is a discussion of the social activity of the people, as evidenced by their skeletal remains. A high development of "squatting" facets in the ankle, tibial, and pelvic joints indicate that the individuals spent a good portion of their lives in positions in which the knees were bent. social and cultural data re-iterate the popularity of the squatting position While at work, eating, and leisure.</p> <p>Comparative data include Tongan, Easter Island, Eskimo, and Indian (North American). It is concluded, from a comparison of the frequency of rocker jaw, that this trait, in all probability, is predominant in Polynesia and appears to be an isolated genetic trait. The diets of the four comparative populations do not appeat to lend any evidence that the trait is a functional development due to hard foodstuffs and/or chewing habits. There is no evidence that the trait is pathological.</p> <p>Statistical results show that the rocker jaw does not have any related characteristics on the mandible. The only significant characteristics are the heights of the corpus at. the molar and premolar levels. These characteristics are necessarily the only points of rocker jaw determination for visual observation. Thus, the rocker jaw appears to be an independent characteristic of the jaw.</p> <p>The best predictors of sex on the mandible, as computed by this study, were the length of the mandible and the molar-premolar chord. These two characteristics were found to have the highest F-ratios (i.e. the most significant) of the sixteen characteristics (or variables) utilized.</p> <p>The major emphasis of the thesis was a statistical study of the rocker jaw through the use of multivariate analysis. The study concludes with the statement that the rocker jaw has no relatec1. characteristics on the mandible (of those measured). It appears that the rocker jaw which has attained a high incidence in certain Polynesian populations, is probably due to genetic drift occurring in small isolated populations.</p>