THE DRYOPITHECUS PATTERN IN RECENT DANES AND DUTCHMEN

¹ National Dental School, Copenhagen, Denmark

In the preface it is emphasized that in accordance with Gregory's original description, the Dryopithecus pattern of the lower molar teeth in simiinids and hominids is a complex of morphologic structures, whose evolutionary changes are little correlated phenotypically, and it is therefore suggested to treat them separately, both descriptively and statistically. This suggestion especially refers to the two structural "elements," the groove pattern and the cusp number. Further, it is suggested to divide the groove pattern into three well-definable, successive stages, indicated by the signs "Y," "+," and "X" (Fig. 1).

Material of recent Danish and Dutch lower molars is described (Tables I, II, and III). In the Dutch series there is a significant difference with regard to the frequency of the Y pattern on the right and left side first molars, and a considerable difference with regard to the cusp number on the right and left side third molars. Similar differences between the right and left sides could not be shown in the Danish series.

In discussing previous observations on the modification degree of the Dryopithecus pattern in the different ethnic groups, it is emphasized that a comparison on an exact statistical basis is rendered difficult by: (a) the absence of a precise definition of the concepts of groove pattern and cusp, (b) the different degree of wear in the specimens, and (c) the lack of a consistent distinction between right and left sides, and between males and females. Instead of discussing the material statistically, I have presented the results graphically (Fig. 2).