CWRU dental students’ summer dig searches for human evolution in Israel

A dozen Case Western Reserve University dental students and faculty members will descend 90 feet to an underground cave in Israel next month as part of an international project to search for insights to evolution from remains dating back as many as 200,000 years.

Working in conjunction with peers and professors at the University of Tel Aviv, the School of Dental Medicine team will examine and recover bones and objects left by ancient cave dwellers under the mountainous city of Manot, Israel, near the border of Lebanon.

Orthodontics chair Mark Hans is planning the trip with Bruce Latimer, an experienced field anthropologist who joined the dental school as a visiting professor last year. Latimer first visited the cave site last summer, while Hans spent time there in December.

Hans said excavation efforts will contribute to the department’s work in the area of human evolution and its connection to modern dental problems such as malocclusion (crooked teeth), caries (tooth decay) and periodontal disease (gum disease).

Added dental school Dean Jerold S. Goldberg: “It is part of the dental school’s ongoing scientific commitment to better understand human craniofacial biology.”

Hans and Goldberg will accompany the students to the dig to get them settled in Manot. Latimer and dental school professors Roma Jasinevicius and Lisa Lang will remain for the rest of trip.

This latest project aligns with Case Western Reserve’s work as part of an initiative called the Legacy Project, a national online collection of major human growth and development databases. Hans maintains the Legacy Project’s Bolton-Brush Growth Study collection, a database of more than 200,000 radiographs that track human growth over eight decades.

Hans and Latimer have worked together closely for more than 25 years. This new collaboration arose after workers first unearthed the historic cave during a 2008 construction project. Israel Hershkovitz from the University of Tel Aviv’s anatomy department rappelled through the hole to assess a large cavern and later found two additional smaller rooms.

The first object found, 30 meters down on the cave floor, was a partial skull. Originally thought to be 20,000 years old, Hershkovitz since determined it to be a 58,000-year-old Neanderthal skull.

“The ground is covered with bones and tools,” said Hans, who visited the cave in December. He said the fire pit, which served as a kitchen area, had charred animal bones and other debris that provides evidence of how the Neanderthals lived.

Latimer and Hans believe much more is hidden below the ground’s surface. Neanderthals were the first hominids to bury their dead, and they did it in their living spaces. Latimer and Hans expect to recover skeletal remains and more over the next decade from the layers of sediment that have filled the cavern’s floor.

Human teeth and the face have changed dramatically over the past least 6 million years, Latimer said. Modern man has a more vertical face, different from these early hominids with jaws that protruded beyond the brain.  In human evolution, teeth are a part of the body that survives the longest, Hans said.

“Our analysis of these differences can provide insight into the development of the modern human face,” Latimer said.

For example, Hans, who studies human facial development, said humans are the only adult animals that cannot eat and breathe at the same time. (Human babies at birth can nurse and breathe simultaneously). When teeth begin to appear and language starts to develop, changes occur in the mandible and maxilla jaw structure that close off the larynx position. As a result, humans now struggle with sleep apnea and choking, which are directly tied to these evolutionary craniofacial structure changes.

The excavation team includes volunteer undergraduate and graduate dental students, incoming dental students in the school’s Doctor of Dental Medicine (DMD) program, and a recent undergraduate who earned a degree in biology and interested in dentistry. They will be in Israel July 8-27. After the Case Western Reserve students depart, the Tel Aviv students will arrive to assume digging in August.