An initial investigation of dental morphology variation among three southern Naga ethnic groups of Northeast India

Abstract

Objectives This study examines dental morphology trait prevalence among three southern Naga groups and compares them to 10 ethnic groups from other regions of South Asia to accomplish two objectives: assess the biological relationship of these Tibeto‐Burman‐speakers to speakers of non‐Tibeto‐Burman languages in other South Asian regions, and determine which traits distinguish northeast Indians from other South Asians. Methods Dental morphology traits were scored with the Arizona State University Dental Anthropology System. Tooth‐trait combinations were evaluated for significant inter‐trait correlation and intra‐trait correspondence within dental fields. Comparisons were based on simple trait prevalence and with Smith's MMD. Affinities based on the former were accomplished with correspondence analysis and principal components analysis. Affinities based on the latter were undertaken with neighbor‐joining cluster analysis and multidimensional scaling. Results After elimination due to inter‐trait correlations and uniform prevalence, biodistances based on the remaining 17 tooth‐trait combinations identify significant differences between northeast Indians and other South Asian ethnic groups due to high frequencies of shoveling on the maxillary incisors and Cusp 6 on the mandibular molars coupled with low frequencies of Carabelli's trait and Cusp 5 on UM1 and UM2, respectively. Conclusions Patterns of biodistances obtained from dental morphology are consilient with those obtained from DNA indicating statistically significant differences between northeast Indians from members of ethnic groups of other regions of South Asia. Researchers should explore the sex‐specific patterns. Biodistances should not be limited to “key” teeth within dental fields, for in almost every case traits present on mesial and distal teeth yield non‐redundant information.

The role of Hazarewal populations in the peopling of South Asia: A dental morphology investigation

“…First, pairwise examination of Cusp 6 trait prevalence found this trait to differ significantly between the four prehistoric Central Asian samples (DJR, KUZ, MOL, SAP) where the trait was completely absent from LM1, and the sample from early Chalcolithic Mehrgarh (ChlMRG) as well as two (CHU, GPD) of the three samples from southeast peninsular India where the trait occurred on 11%-21% of LM1s assessed. Second, the presence of Cusp 6 on LM2 was found to differ significantly among three living samples from northeast India (11.9%-29.1%) relative to those from peninsular India (Hemphill et al, 2019;Pojar et al, 2020). 9 Since the same set of variables were also used to examine biodistances for archeologically derived prehistoric samples in which the dental remains are often fragmentary and unassociated with sexually diagnostic skeletal and cranial features, no assumptions could be made about the relative proportion of females to males in these samples.…”

“…Observations were made on both right and left antimeres. Frequencies of dental traits were calculated for each grade of expression following the procedure described in Pojar et al (2020). All casts were scored by BEH whose scoring concordance was found to be highly reliable (Pojar et al, 2022).…”

“…Proponents of the Neolithic farming model (NFM) maintain that peoples of West Eurasian ancestry migrated to India with the spread of agriculture in a demic diffusion manner (Cordaux et al, 2004) similar to that observed for the spread of Near Eastern cultigens to Europe (Chikhi et al, 2002; Pinhasi & von Cramon‐Traubadel, 2009; Skoglund et al, 2012; Sokol et al, 1991). The Neolithic revolution in the greater Fertile Crescent was not a singular event but a series of events at differing localities across several millennia (Brown et al, 2009) throughout the northern and southern Levant beginning in the 10th millennium BC and reaching an apogee primarily during the 8th millennium BC (Fuller et al, 2011).…”

“…First, pairwise examination of Cusp 6 trait prevalence found this trait to differ significantly between the four prehistoric Central Asian samples (DJR, KUZ, MOL, SAP) where the trait was completely absent from LM1, and the sample from early Chalcolithic Mehrgarh (ChlMRG) as well as two (CHU, GPD) of the three samples from southeast peninsular India where the trait occurred on 11%–21% of LM1s assessed. Second, the presence of Cusp 6 on LM2 was found to differ significantly among three living samples from northeast India (11.9%–29.1%) relative to those from peninsular India (Hemphill et al, 2019; Pojar et al, 2020).…”