Morphological variation of the deciduous second molars in the Baka Pygmies

Abstract

The Baka Pygmies are known for their short stature resulting from a reduced growth rate during infancy. They are peculiar also for their teeth erupt earlier than in any other African population, and their posterior dentition is larger than in non-Pygmy populations. However, the Baka’s dental morphology, like several other aspects of their biology, is still understudied. Here, we explore the variation of the Baka’s deciduous upper and lower second molars (dm2s) in comparison to a geographically heterogeneous human sample by means of 3D geometric morphometrics and analysis of dental traits. Our results show that the different populations largely overlap based on the shape of their dm2s, especially the lower ones. Their distal region and the height of the dentinal crown differ the most, with the Baka showing the most extreme range of variation. Upper and lower dm2s covary to a great extent (RV = 0.82). The Baka’s and South Americans’ dm2s were confirmed among the largest in our sample. Despite the Baka’s unique growth pattern, long-lasting isolation, and extreme dental variation, it is not possible to distinguish them from other populations based on their dm2s’ morphology only.

Shape variation in modern human upper premolars

“…Additionally, the overlap between South American and Near Eastern populations was minor. Prevailing short and broad posterior dental crown types including its extreme expressions, like in the Near Easterners, were already described for African populations [ 46 , 54 ]. As mentioned above, small sample sizes of various populations have to be acknowledged, as well as the different number of sub-samples within geographical populations.…”

“…The EDJ thus represents an appropriate alternative to the OES since it also bears relevant taxonomic information [31,37,39,43,44]. Morphometric studies of the EDJ of both permanent and deciduous molars are well represented in the literature [31,33,[44][45][46], while for maxillary premolars, extensive comparative studies are very rare [47], or only focused on the descriptive assessment of the EDJ and OES [48][49][50][51]. Currently, 3D geometric morphometric (GM) analyses of the inner tooth crown variation in geographically diverse modern human samples have been published for permanent and deciduous molars [23,33,44,46,47,52], as well as lower premolars [53,54], and central incisors [55].…”

“…Morphometric studies of the EDJ of both permanent and deciduous molars are well represented in the literature [31,33,[44][45][46], while for maxillary premolars, extensive comparative studies are very rare [47], or only focused on the descriptive assessment of the EDJ and OES [48][49][50][51]. Currently, 3D geometric morphometric (GM) analyses of the inner tooth crown variation in geographically diverse modern human samples have been published for permanent and deciduous molars [23,33,44,46,47,52], as well as lower premolars [53,54], and central incisors [55]. These studies did not detect geographically-dependent dental shape variation [33,54], thus, in the current study, we applied quantitative approaches to explore inter-and intra-population shape variation and covariation of modern human P3s and P4s, expecting to find similar outcomes.…”

Descriptive Study of Oral Health in an Indigenous Child Population of Baka Pygmies in Cameroon

“…The first inhabitants of the Cameroonian forest, the Baka pygmies, who are part of the indigenous peoples found in Cameroon, are characterized by an average male height of less than 155 cm, a hunter-gatherer lifestyle, and practices such as the use of plants and plant fibers for therapeutic purposes and also dental mutilation, which, as in several equatorial African countries, remains a technically traumatic act [13,20,21].…”