The Ungar Lab is involved in many projects at any given time. Explore our different research pages to learn more about what is happening in the lab.
Environmental change in Western Siberia: Interactions of land surfaces, animal communities, infrastructure, and peoples of the Arctic
Team Members: Peter Ungar, Valeriy Ivanov, Alexander Sokolov, John Ziker, Natalya Sokolova, Andrew Dixon, Mary Heskel, Dorothee Ehrich, Konstantin Gribanov, Desheng Liu, Aleksey Sheshukov, Victor Valdayskikh, Jingfeng Wang, Olivier Gilg, Valeriy Mazepa, Alexandra Terekhina, Alexander Volkovitskiy
Funding Source: US National Science Foundation
This project will bring together earth system scientists, engineers, ecologists, and anthropologists to develop a plan to document and explain changes in ecosystems and their effects on the plants, animals, indigenous peoples, and industrial infrastructure of the Arctic region. It will emphasize interactions between these elements to help understand, inform, and plan for changes to come. Researchers will focus on the Yamal Peninsula of Russian Siberia. Yamal presents a continuous gradation of habitat types from forest in the south to tundra in the north, a rich diversity of endemic and invasive plant and animal species, a large population of traditional peoples, and economically critical natural resources. Local stakeholders will be engaged throughout the project, including representatives of government and industry in Yamal and indigenous Nenets communities in the region.
This project is important because the Yamal Peninsula serves as a small-scale and manageable model for the Arctic as a whole, wherein changes in climate and their effects on temperature, precipitation, landform, plants, animals, peoples, and infrastructure need to be understood and related to one another. This work will contribute to curriculum development for collaborative, transdisciplinary online inter-institutional undergraduate and graduate courses to train the next generation of scientists to take a holistic approach to problem solving.
Dental wear of rodents from the Yamal Peninsula as a proxy for habitat
Team Members: Peter Ungar, Lindsay Saylor, Kaitlyn Puyear, Jacob Purifroy, Olivier Gilg, Alexander Sokolov, Natalya Sokolova, Sophie Montuire, Aurelien Royer
Funding Source: University of Arkansas Honors College
This project will consider variation in microwear texture patterns on the incisors of lemmings and voles as well as gross wear of cheek teeth of voles along a north-south gradient in the Yamalo-Nenets Autonomous Okrug. The Yamal Peninsula and adjacent Belyi Island represents a series of ecological zones and microhabitats that might be distinguished by wear pattern. We hope to develop a proxy by which we can reconstruct habitat in the past, gauge environmental variation today, and monitor effects of climate change into the future.
Dental wear and breakage for Arctic Foxes from the Yamal Peninsula as indicators of dietary stress
Team Members: Peter Ungar, Blaire van Valkenburgh, Alexander Sokolov, Natalya Sokolova, Alex Peterson
This project considers dental microwear, gross tooth wear and patterns of antemortem fracture of the dentitions of Arctic foxes as a proxy for dietary variation associated with varying food availability across time and space in the Yamalo-Nenets Autonomous Okrug. We hope to develop a proxy by which we can assess impacts of climate change in the Arctic on endemic mammals, including foxes.
Paleontology and bioarchaeology
Canine use in hominins
Team Members: Lucas Delezene, Peter S. Ungar, J. Michael Plavcan, Mark Teaford
Funding Source: Leakey Foundation
Using dental microtexture analysis, we are examining the hypothesis that early hominins used their canines in ingestive behaviors. To do so, we will compare microwear in five hominin species to that of a range of anthropoid primates that use their canines in a variety of preparatory and nonmasticatory contexts.
Predmostí canid microwear
Team Members: Kari Prassack, Peter S. Ungar, Josie DuBois, Martina Laznickova-Galetova, Mietje Germonpre.
We are examining microwear textures on the carnassials and postcarnassial teeth of fossil canids from the site of Predmosti in the Czech Republic. Some researchers have distinguished “protodogs” from wolves at this important Upper Paleolithic site, and hence Predmosti is an important key to debates concerning the initial domestication of dogs. Our project will contribute to the discussions by testing the hypothesis that samples identified as protodogs had different diets than those recognized as wolves.
Microwear of Norse and Thule inhabitants of Greenland
Naseer Nassem, Peter Ungar, Lucas Delezene
Funding Source LSB Leakey Foundation
The fate of Greenland’s Viking settlements remains a topic of intense debate among archaeologists and historians. Why did they disappear whereas the Thule survived and thrived to become today’s Greenlandic Inuit? We are comparing dental microwear patterns on the molar teeth of early Viking and Thule settlers at sites from around Greenland. The goal is to determine whether there were differences over time and space, both within and between groups, in diet that might contribute to the discussion.
Dental microwear analysis development
Dental biotribology and microwear/nanowear formation
Team Members: Jing Xia, Peter S. Ungar, Licheng Hua, Zhong-rong Zhou, Jing Zheng, Linmao Qian, David Daegling, Jean-Francois Meullenet, Ryan Tian.
Funding Source: The National Academy of Science of China, Southeastern Conference
We are using principles from engineering to study the tribological properties of teeth. Our work focuses on the etiology of microwear and nano-scale tooth wear in light of the biomechanical and chemical properties of tooth enamel. This has involved a series of in vitro experiments involving chewing machines, nanoindentors, atomic force microscopes, instron machines and other instruments to work out the conditions and processes underlying the removal of enamel tissue from tooth surfaces.
Comparative study of anterior dental microwear in recent foragers and non-human primates
Team Members: Lucas Delezene, Peter S. Ungar, Mark Teaford, Taylor Spillers, Sara Jeffress
Funding Source: LSB Leakey Foundation
This project involves a comparative study of dental microwear textures in non-human primates and human foragers to establish a baseline for comparison with early hominins and other fossil primates. Our work is focused on documenting diet-related variation microwear textures related to ingestive behavior in extant apes and sympatric primates as well as paramasticatory tooth use in recent hunter-gatherers.
Dental topographic analysis development
Relationships between dental topography and diet in platyrrhine primates
Team Members: Carrie Healy, Aleksis Karme, Mikeal Fortelius, Peter Ungar, Mark Teaford
Funding Source: LSB Leakey Foundation
This project involved generating and laser scanning high-resolution replicas of the upper second molars of 341 wild-caught individuals from 16 species of platyrrhine. Specimens were grouped by reported dietary preference into frugivores, gummivores, folivores, and seed eaters. Additional analyses were conducted on the frugivores alone, separating those that
supplement their diets with hard objects, insects, leaves, and seeds. Results indicate that each preferred diet type shows a distinctive combination of occlusal slope, relief, angularity, sharpness, and orientation patch count (rotated) for given gross wear categories. Furthermore, among the frugivores, secondary diet groups were also well separated.
Development of new approaches to characterizing dental topography in mammals
Team Members: Peter Ungar, David Polly, Richard Leach, Danny Sims-Waterhouse, Sofia Catalucci
Mammalian teeth have become a model system for evolutionary, developmental, and functional biologists to explore form-function relationships and their roles in ecology and evolution. There has, however, been no comprehensive study of relationships between dental form and function across the entire clade. The aim of this project is to develop a portable system for scanning teeth ranging from mice to mammoths with sufficient resolution and speed to generate comparable topographic models of all mammalian dentitions. The ultimate goal is to apply this system to species representing all higher-level clades of mammals and determine whether there are any “universal rules” by which form relates to function across the class.
Oral Health/clinical applications
Hadza oral health research
Team Members: Peter S. Ungar, Alyssa Crittenden, John Sorrentino, Jerry Rose
Funding Source: US National Science Foundation
Our group recently examined oral health in the Hadza peoples of Tanzania, the last remaining hunter-gatherers in Africa. Our research has focusing on changes in caries rate, periodontal disease, orthodontic disorders and developmental defects associated with the transition from foraging for wild foods to an agriculture-based village subsistence.
Objective outcome measures for the clinical assessment of erosive tooth wear
Team Members: Anderson Hara, Dylan Elkington-Strauss, Peter Ungar
Funding Source: US National Institutes of Health
Erosive tooth wear (ETW) is a multifactorial and cumulative condition of growing prevalence that leads to substantial loss of dental structure, resulting in pain and harm to dental function and esthetics. Currently, the clinical assessment and monitoring of ETW is done by visual examination using subjective indices. The long-term goal of this study is to develop a non-invasive and nondestructive clinical assessment for the detection, differentiation and monitoring of ETW progression. This assessment will be based on the clinical measurement of enamel thickness and dental surface texture by polarization-sensitive optical coherence tomography (PS-OCT) and white-light scanning confocal profilometry (WLSCP), respectively. The hypothesis to be investigated is that the combination of surface texture and enamel thickness analyses can provide objective and reliable information for the diagnosis and monitoring of ETW. Evaluations are being performed at baseline and after 3, 6, 9 and 12 months. This research will provide the basis for the development of an objective clinical assessment protocol to diagnose and monitor ETW development, identifying its relation to biological and behavioral factors.
Clinical applications to dental topographic analysis
Team Members: Anderson Hara, Carlos Gonzales, Peter S. Ungar, Grace Roberts, James Needy, Sarah Buedel
These projects involve study of dental topography of premolar teeth of dental patients. We are exploring several applications involving use of intraoral scanners in clinical settings to document patterns of gross tooth wear and assess possible associations between occlusal fissure topography and caries incidence. We are also using in vitro experimental approaches to assess changes in functional occlusal topography with dental attrition.
Surface analysis of brushed enamel surfaces
Team Members: Anderson Hara, Cecilia Turssi, Gracie Engelkes, Peter S. Ungar
This project investigates the ability of SSFA and ISO parameters to assess the microscale effect on dentin/enamel of toothbrush stiffness and abrasivity of toothpastes as an alternative to the current radiotracer method.