Compensatory tooth size interaction in a preliterate population

Abstract

The negative correlation between outsized early developing teeth and their later developing neighbours presupposed by Sofaer's model of compensatory tooth size interaction is evaluated in a preliterate human population. Mesiodistal and buccolingual measurements on the permanent dentition of 202 Paraguayan Lengua Indians showed a significant positive correlation between larger than average first molars, incisors and premolars and their later developing second molars, incisors and premolars. An equally significant positive relation between phenotypically extreme early develping teeth within a tooth class (i.e. larger or smaller than one standard deviation from the population mean) and their later developing neighbours was demonstrated. Our findings not only allow us to reject Sofaer's model but to question his selectionist jaw-tooth reduction model. It is suggested that the reported patterns of human tooth size reduction are manifestations of neither active selection nor of reduced selection resulting from underutility associated with increased culinary sophistication, but rather of random demic variation.