The Roles of Genetic Drift and Natural Selection in Explaining the Unusual Dental Pattern of New Guinea Highlanders

University of Nevada, Reno Adrift in Oceania: The Roles of Genetic Drift and Natural Selection In Explaining the Unusual Dental Pattern of New Guinea Highlanders A thesis submitted in partial fulfillment of the requirements for the degree of Master of Arts in Anthropology by Roman Schomberg Dr. G. Richard Scott/Thesis Advisor May, 2018 THE GRADUATE SCHOOL We recommend that the thesis prepared under our supervision by ROMAN SCHOMBERG Entitled Adrift In Oceania: The Roles Of Genetic Drift And Natural Selection In Explaining The Unusual Dental Pattern Of New Guinea Highlanders be accepted in partial fulfillment of the requirements for the degree of MASTER OF ARTS G. Richard Scott, Ph.D. , Advisor Marin Piloud, Ph.D., Committee Member Chris Feldman, Ph.D., Graduate School Representative David W. Zeh, Ph.D., Dean, Graduate School May, 2018 i Abstract A primary goal was to resolve the ‘baffling convergence’ of New Guinea and European dental morphology. This is an unusual case where dental morphology is at odds with other lines of biological evidence that show close ties between New Guinea and Australian populations. Observations were made on 182 dental casts from living populations in the New Guinea Highlands to characterize their dental morphology. Trait frequencies were compared to those of world populations to compute distance statistics and derive dendrograms. The conundrum was solved to a large extent when variation of the EDAR gene variant 370A was taken into account. This gene is associated with multiple traits involving hair, skin, and teeth. The high frequency of this polymorphism in North Asia is associated with a high frequency of shovel-shaped incisors. The EDAR 370A gene is not only associated with shoveling but also with double shoveling and lower molar cusp number. Although the gene is in moderate to high frequencies throughout Asia and the Pacific, it is absent in New Guinea. When the dental traits associated with EDAR were removed from the distance analysis, New Guinea now linked with Australia and Melanesia rather than Europe. This suggests that the unusual dental pattern exhibited by New Guinea Highlanders is a product of both genetic drift and natural selection. When compared to other populations, non-EDAR linked traits exhibit distance values that are in accord with differentiation attributable to genetic drift. The EDAR-linked traits reflect selection that has driven the frequency of this gene to zero. In all likelihood, the dental traits associated with EDAR are ‘genetic hitchhikers’ associated with some skin and/or hair trait that have been influenced by selection in this tropical rainforest environment. Although the nature of this selection cannot be determined, at least the ‘baffling convergence’ of New Guinean and European tooth crown morphology has been ‘unbaffled.’ ii I’d like to dedicate this to my mother. Since I was a small child, she pushed me towards the path of knowledge and curiosity. iii Acknowledgements I would like to than R.A. Littlewood for graciously lending the collection of dental casts to the University of Nevada Reno. This exemplifies all that is good about the scientific process and I am grateful to have had the opportunity to study the fruits of his labor. A great deal of gratitude is owed to the late Christy G. Turner II. His relentless work ethic produced an inspiring volume of data. It has made possible, not only this study, but countless others far ranging research on population origins and relationships. He was a true scientific pioneer and his legacy continues to grow not only through his work, and that of his students and colleagues; but also, I must imagine, through anyone who called him a friend or family member. I am extremely grateful for my committee members: Dr. G. Richard Scott, Dr. Marin Piloud, and Dr. Chris Feldman, for their guidance, patience, and most importantly, their expertise. iv Table of Contents Introduction .................................................................................................................. iv Materials and Methods ................................................................................................... 9 ASUDAS Descriptions ........................................................................................................ 11 Upper Dentition ............................................................................................................................. 11 Lower Dentition ............................................................................................................................ 16 Results .......................................................................................................................... 23 Distance Measures .............................................................................................................. 35 Clustering ........................................................................................................................... 37 Discussion .................................................................................................................... 39 Conclusions .................................................................................................................. 45 Appendix ...................................................................................................................... 49 References .................................................................................................................... 50 v List of Tables 1. Table 1. Mean crown frequencies for 16 world groups plus New Guinea Highland sample 2. Table 2. Crown frequencies for 15 world samples and 17 nonmetric crown traits 3. Table 3. Euclidean distance values between 17 regional groupings and from 19 nonmetric crown traits 4. Table 4. Euclidean distance values between 16 regional groupings and from 17 nonmetric crown traits 5. Table 5. Frequencies and mean trait scores for UI1 Shoveling for 9 archaeological samples and 5 living samples vi List of Figures 1. Figure 1. UPGMA tree based on distance analysis of 23 crown and root traits in 21 regional groupings. Modified from Scott and Turner (1997) 2. Figure 2. UPGMA tree based on distance analysis of 9 crown and root traits in 43 regional groupings. Modified from Scott and Turner (1997) 3. Figure 3. Photo of UI1 Winging 4. Figure 4. Box and whisker plots based on world frequencies of UI1 Winging Figure 5.2 from Scott et al. (2018) 5. Figure 5. Box and whisker plots based on world frequencies of UI1 Shoveling Figure 5.3 from Scott et al. (2018) 6. Figure 6. Photo of UI1 Shoveling 7. Figure 7. Photo of second upper molar without a hypocone 8. Figure 8. Box and whisker plots based on world frequencies of UM2 Hypocone Figure 5.11 from Scott et al. (2018) 9. Figure 9. Box and whisker plots based on world frequencies of UM1 Cusp 5 Figure 5.13 from Scott et al. (2018) 10. Figure 10. Photo of Cusp 5 on the first upper molar 11. Figure 11. Box and whisker plots based on world frequencies of LM1 Cusp 6 Figure 5.18 from Scott et al. (2018) 12. Figure 12. Photo of Cusp 6 on the first lower molar 13. Figure 13. Photo of 4 cusped second lower molar vii 14. Figure 14. Box and whisker plots based on world frequencies of 4 cusped LM2 Figure 5.16 from Scott et al. (2018) 15. Figure15. First data set - Dendrogram displaying results from Euclidean distance and UPGMA clustering. 16. Figure16. Second data set - Dendrogram displaying results from Euclidean distance and UPGMA clustering. 17. Figure17. First data set - Dendrogram displaying results from Euclidean distance and UPGMA clustering without EDAR linked traits 18. Figure18. Second data set - Dendrogram displaying results from Euclidean distance and UPGMA clustering without EDAR linked traits 1 Introduction Physical anthropologists are interested in the origins, diversity and evolution of humans, their ancestors and relatives. Adding data to the body of anthropological literature helps clarify the picture of our origins and variation. Studying a particular region not only illuminates its own history but also helps answer broader questions of human variation and dispersal. The purpose of this study is to address the dental morphological variation of the long-isolated populations of the New Guinea Highlands. New Guinea is a large island north of the Australian continent. The two landmasses and their neighboring islands were linked to form the continent Sahulland until the end of the Pleistocene (Allen and O'Connell 2008). Sea levels began to rise around 15,000 years ago, separating the island of New Guinea from the continent of Australia (O'Connell and Allen 2004). The geographic history of New Guinea and Australia suggests their inhabitants could be related or share common ancestry at some point in time. Geography alone cannot answer this question. Other lines of evidence, such as archaeology, genetics, craniometrics, non-metric cranial traits, and dental morphology, are required to evaluate the extent of shared ancestry between the populations of New Guinea, Australia, and nearby islands. The Pleistocene continent of Sahulland included Australia, New Guinea, Tasmania, the adjacent continental shelves, and small islands nearby when Pleistocene sea levels were lower than in modern times (O'Connell and Allen 2004). Dates for the human settlement of Papua New Guinea have been estimated at 40,000 years ago in the 2 Huon Peninsula (Groube et al. 1986). The date of this site was subsequently revised to be 47,000 to 61,000 years old using uranium-thorium

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