Dental microwear of living Hadza foragers

Abstract

Objectives: Studies of dental microwear of bioarchaeological assemblages and extant mammals from museum collections show that surface texture can provide a valuable proxy for reconstructing diets of past peoples and extinct species. However, no study to date has focused on occlusal surface microwear textures of living hunter-gatherers. Here we present the first such study of the Hadza foragers of Tanzania. Methods:We took high-resolution dental impressions of occlusal surfaces for a total of 43 molds representing 25 men and women, 1-3 samples each, at different times during the rainy and dry seasons. Dental replicas were prepared and scanned by confocal profilometry and standard microwear texture parameters were calculated. Central tendencies and dispersions of variable scores were compared by season and by sex.Results: We found no differences between sexes or seasons in texture attribute central tendency, but some for dispersion. Females had notably low microwear texture dispersion in the dry season while males had higher dispersion in some attributes, particularly in the dry season. These differences seem to be driven primarily by low variance among females in the dry season.Conclusions: This study demonstrates microwear texture data can be generated for living foragers. Given caveats of small samples available and consideration of foraging groups in transition, this study hints at variation in microwear texture dispersion between sexes and seasons for the Hadza, suggesting that such analyses might be of value for assessing hunter-gatherer diet. K E Y W O R D Sdiet, hunter-gatherers, tooth wear

Applying dental microwear texture analysis to the living: Challenges and prospects

“…Nevertheless, the results of this study may also be interpreted as a true negative, indicating dietary homogenization in the context of modernization, just as suggested by Ungar et al (2019) for the Hadza.…”

“…Indeed, as it stands, there is no fool proof way to completely remove biofilm without producing new microwear, a fact already pointed out by Teaford and Oyen (1989a, p.75). From the 15 studies included in Table 5, only 4 studies (other than the present) allude to success rates (Nystrom et al, 2004;Percher et al, 2018;Raphael et al, 2003;Ungar et al, 2019), rendering further comparison of the success of the different techniques impossible. In detail, Nystrom et al (2004) state that they did not find any residual adherent film or moisture, suggesting a 100% success rate; Ungar et al (2019, p. 358) simply mention that "dental biofilms were difficult to remove and many of the impressions taken were not usable"; Raphael et al (2003) noted that they could obtain good impressions from 52 out of 63 dental patients (specifically stating that organic film obscured microwear features in impressions from 11 individuals); and Percher et al (2018) state that they were able to obtain usable facets from 48 out of 92 individuals.…”

“…However, of relevance here, esekon is also known for being used for longer periods of time, often several times a day, primarily on the anterior teeth, and for being potentially tougher than conventional toothbrushes, all of which can impact on patterns of dental microwear rely heavily on C 4 foods (Correia et al, 2019). C 4 foods are often cereals, which are known for leaving distinct marks on teeth (Bullington, 1991;Ungar et al, 2019), although this may also depend on the manner of cereal processing rather than on the properties of the cereals themselves (Mahoney, 2006;Schmidt et al, 2015;Teaford & Lytle, 1996). However, just like Ungar et al (2019), the present study found that biofilm removal from the teeth of living individuals is very problematic, and hence that we could not confirm if the microwear textures of the studied groups recorded the known differences in their diets although the high effect sizes suggest they do.…”

“…In addition, the procedure was repeatedly practiced on (open-minded and) willing office colleagues, and at the time, molding and casting seemed successful under a standard light microscope. Here, we must consider that dental biofilms may vary substantially between individuals and groups depending on diet abrasiveness and dental hygiene habits, although the method used was specifically designed to be applied to a hunter-gatherer population among whom biofilms were expected to be substantial (Ungar et al, 2019). The subsequent casting protocol was implemented in laboratory conditions at Cambridge, and hence, some issues might have arisen at this point (e.g., type of centrifuge used, for example).…”

“…Dental microwear studies on living primates (Nystrom, Phillips‐Conroy, & Jolly, 2004; Percher et al, 2018; Teaford et al, 2020; Teaford & Oyen, 1989a; Teaford, Ungar, Taylor, Ross, & Vinyard, 2017) and on living people (Romero, Ramírez‐Rozzi, De Juan, & Pérez‐Pérez, 2013; Teaford & Tylenda, 1991) have been carried out before using the more traditional SEM protocol. However, DMTA of a living human group has only been attempted once before by Ungar, Livengood, and Crittenden (2019), and this study focused on a single group, rather than on between‐group differences in dental microwear that could reflect diet. Within this context, the present work used DMTA to study the dental microwear of five Kenyan contemporary populations with three different subsistence strategies (fishing, farming, and pastoralism), being thus the second study to target living human groups, and the first to investigate diets other than foraging.…”