Research

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.

Arctic research

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, Bruce Forbes, Natalya Sokolova, Andrew Dixon, Loïc Bollache, 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. 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.  The project will contribute to the curriculum development for a collaborative, transdisciplinary online inter-institutional undergraduate and graduate courses to train the next generation of scientists to take a holistic approach to problem solving. Stakeholder engagement will include those representing government and industry in Yamal and the aboriginal Nenets people of the region.

Dental microwear of rodents from the Yamal Peninsula as a proxy for habitat

Team Members: Peter Ungar, Lindsay Saylor, Kaitlyn Puyear, 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 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 incisor microwear 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.

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 

Team Members:
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.