CORDIS - EU research results

Evolution of cell mechanisms underlying human dental reduction in Europe

Periodic Reporting for period 1 - REDUCTeeth (Evolution of cell mechanisms underlying human dental reduction in Europe)

Reporting period: 2018-10-01 to 2020-09-30

The human skeleton has continued to evolve over the past 40,000 years in Europe, long after the emergence of our species. During this period, major social, technological and demographic changes occurred as a mobile hunter-gatherer lifestyle gave way to sedentary farming villages, and then cities. This was accompanied by biological changes to our skeletons, which are retained into the present day. Our skeleton retains these biological changes into the present day, which include a decrease in skeletal robusticity, a shortened facial region, and smaller jaw and teeth, when compared to our distant ancestors. One of the most striking changes is the reduced size of our teeth and jaws. This dental reduction contributes to dental crowding for modern day Europeans, which requires extensive orthodontic treatment with a significant global socio-economic cost. These distinctive skeletal features of modern humans have led to many present day dental health and orthodontic problems, including dental crowding and malocclusion that continue to drain clinical dental practitioner's time, and public funds allocated to dental treatment for children.

Despite 50 years of academic debate amongst anthropologists and even though several hypothetical models have been developed to infer the causes of dental reduction, a consensus has still to be reached. Yet, we know nothing about the cell mechanisms that actually facilitated the reduced size of our teeth and jaws in Europe.

The goal in this project is to develop an original, interdisciplinary and holistic approach that combines dental and bone analysis at three structural levels, to identify and describe the micro-evolutionary cell mechanisms that led to the reduction of modern human teeth and jaws in Europe. Combining cutting-edge histological and microtomographic techniques, I will examine molars and jaws from prehistorical, medieval and modern samples, spanning our most recent evolution from ~38,000 years ago to the present day. The overall objectives are 1) to identify the cell mechanisms governing tooth size and jaw size, 2) to assess growth, proportions and size of teeth and jaws in late Pleistocene and Holocene human populations and 3) to re-evaluate the existing hypothesised causes of dental reduction. This project will provide a unique biological insight that will help to resolve a long-standing debate, and reshape our understanding of dental reduction during recent human evolution.
A significant amount of world-leading dat has been collected during multiple research trips. Several milestones have therefore been completed through external morphological analysis and microCT analysis. Milestones for histological analysis have been partly completed, although I had planned more data collection in the Kent laboratory but was unable to complete it due to Covid-19 constraints.

I acquired solid and complete technical skills in dental anthropology, from “classic” morphometric analysis through dental tissue proportions and shape analyses via 3D high-resolution imaging and geometric morphometrics, and microstructural histology studies of short and long periodicity increments recorded in dental tissues. Additionally, I gained an understanding of dental microwear texture analysis. Being able to perform all these analyses by myself is essential for the development of a holistic and interdisciplinary approach, which was one of the goals of my project. Additionally, my communication skills have greatly improved over the course of the project, not only within an academic environment but also for exchange with the general public, through my outreach work at the University of Kent.

Results have been presented at several international conferences thanks to a total of 10 podium and poster presentations. One journal article specifically related to my project, and two book chapters, have been submitted and are currently in review. Collaborations linked to samples studied in this project have resulted in three other published journal articles.
Using advanced histology and 3D imaging technology to examine molars and jaws from Pleistocene and Holocene samples will unlock the micro-evolutionary cell mechanisms that led to the reduction of human teeth and jaws, and ultimately provide general rules governing bio-environmental interactions through time, as well as underlying causes of the evolutionary trends observed in the human lineage.

Results will be of interest to anthropologists, biologists, and the general public. My project can also contribute new information for clinical orthodontic treatment.
Meso- and micro-analysis of teeth and bones thanks to virtual and histological techniques.