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An integrative analysis of shifting trends in dental traits in human populations from Neolithic to Iron Age

Periodic Reporting for period 1 - ANCIENT_TEETH (An integrative analysis of shifting trends in dental traits in human populations from Neolithic to Iron Age)

Reporting period: 2016-06-06 to 2018-06-05

The transition to farming was among the most significant events in human history driving major biological and cultural change globally. Agriculture arrived the Great Hungarian Plain (GHP) no later than 6,000 BC. Among the archaeological remains, teeth constitute the fossil evidence most widely used in paleoanthropology research for interpreting the biology of extinct species, including on our own species as they have a strong genetic component. Although teeth have been traditionally used for the study of diets of past population, the morphological change in dental tissues associated with cultural transitions has yet to be examined. This project’s main aim is to study the changes in dental traits of human past populations as indicators of genetic replacements and dietary shifts (or lack thereof) following the transition to agriculture in the GHP, from Early Neolithic to the Iron Age period, utilizing multidisciplinary state-of-the-art methods. This project will help to understand the adaptive process that past human teeth suffered when facing important challenges in the subsistence way of life. Additionally, this project will help to understand how our genetics can be indirectly interpreted from teeth, and hence, to increase our knowledge of past population migratory movements.
Dental morphology changes through time- The Fellow collected samples from Miskolc Museum (Hungary) of Neolithic to Iron Age human remains, additionally to the ones available in Prof. Ron Pinhasi’s lab (University College Dublin-UCD, Ireland). The teeth samples were scanned in Cambridge Biotomography Center (CBC) in collaboration with Prof. Jay Stock (University of Cambridge-UCAM, UK). The Fellow got trained in 3D scan processing and modelling (UCAM and University of Bologna-UB, Italy), as well as in 3D Geometric Morphometric (GM) software (UB) in Prof. Stefano Benazzi’s lab. She obtained the 3D model of the enamel-dentine-junction (EDJ) of the molars in the facilities of the Health Science Center (UCD) supervised by Dr. Robin Feeney, and analysed the dental morphology of some of the models obtained. Preliminary results suggest that differences exist between the EDJ of first upper molar of Copper Age and Bronze Age peoples, suggesting that EDJ can be used a genetic proxy to interpret migration movements in past populations.
Diet changes through time- Bone collagen was extracted from human and faunal remains from Neolithic to Iron Age in UCD, and stable isotope data was obtained. The results suggest that the people who lived in the GHP from Neolithic to Early Bronze Age were consuming C3 cultivated plants, such as wheat and barley, and different amounts of meat as a result of their farming practices. However, it is during the Late Bronze Age that people began to consume other types of C4 plant, including millet, in accordance with the rest of continental Europe. This new crop was most probably brought in from people from the east, as a result of a migration wave during the Bronze Age.
Molecular sex by ancient DNA (aDNA) methods- The Fellow extracted and sequenced aDNA from the petrous bone and teeth of human remains in UCD and University of Vienna (UV). The molecular sex was obtained by performing standard bioinformatics analysis. These results are expected to be published in combination of new isotope and morphometric data in order to analyse dietary and dental morphology differences between sexes.
Exploitation and dissemination of the results/project- The Fellow presented ANCIENT_TEETH project in UCD “School of Archaeology seminar day”, in December 2016. She also disseminated the first isotope results of the project at two venues: 1) in the EAA congress (September 2017), and 2) in the “Ancient Food seminar-series” (UCD, October 2017). There, she presented part of the isotope results along with a discussion about her project under the topics “What do teeth tell?” and “We are what we eat”. Some isotope data (48 individuals) were published in a high-impact factor journal in May 2018 (http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0197214). The rest of the isotope samples are expected to be published along this year 2018. Some of them, combined with microwear patterns, and in collaboration with IPHES (Spain), will be disseminated in the next EAA meeting (September 2018) and published in a high-impact journal. Finally, it is expected to publish the results of the complete isotope data (142 individuals) obtained from the project in a final publication, combined with molecular sex data. Dental morphology results are expected to be published along first term 2019. Finally, the Fellow was able to create a personal website (https://beatrizgamarrarubio.com/) to increase the visibility of her research as well as to promote the current project and its achievements.
Internal morphology of dental tissues, such as the EDJ and shape studies employing GM and microCT methods have been traditionally employed in primates, including humans and ancient human ancestors. In this project, these methods are employed for the first time to the study of dental trait changes from prehistoric populations that lived in the GHP. It is expected that, because teeth are under strong genetic control, population movements into the area may have changed the morphology of the EDJ of prehistoric populations, and hence, can be used as a genetic proxy. The results obtained thus far suggest that differences exist between the EDJ of first upper molar teeth of Copper Age and Bronze Age peoples. These results are in accordance with recent genetic studies of the same area that suggest genetic shifts, probably as a result of a human migration movement. These results therefore imply that morphological traits of the EDJ reflect genetic differences as a result of population genetic influx. Moreover, these non-destructive state-of-the-art approaches may be used to resolve and better interpret socio-economic caused events that occurred in the past.
The study of stable isotopes as a dietary proxy performed in this project contributes to identify the subsistence practices used by ancient peoples associated to different cultures. It is expected that dietary shifts occurred with the advent of the new technological and cultural changes. The subsistence practice of Bronze Age and Iron Age populations from the GHP have never been analysed from a socio-economic past context. The results from this project suggest that there were important changes in dietary pattern in GHP during the Late Bronze Age with higher millet consumption, probably brought by people from the East.
The study of past dental change related to shifts in dietary regimes is of great interest to anthropological science as well as dentistry and human health science. In this sense, the impact of this research will contribute to expand the knowledge of the adoption of the agriculture and following cultural transitions through a dental morphology perspective. Additionally, understanding the effects of diet changes in past populations will help to explain the origin of challenging dental health problems of contemporary people. In doing so, we will understand the adaptability of human teeth to current and future dietary changes. Finally, the data produced from high-resolution scans of human teeth for the study of dental change is an invaluable resource for evidence-based research proposals calling for change in health policies of European countries.
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