Asking Questions with Ancient Animal Bones

Miriam Belmaker asks questions. As an assistant professor of anthropology, she has dedicated her life to bold and intrinsic questions on human evolution. What makes us human? This summer, Belmaker traveled to Kazakhstan and South China in search of answers.

Sifting through dirt.

Belmaker is a paleoecologist who uses small mammals to reconstruct ancient environments where ancient humans lived. To reconstruct the climate, Belmaker “looks at the chemistry, shape and wear patterns of the teeth to see if they were eating different kinds of foods,” she said. “We look at the striation of the teeth that allows us to distinguish if they are eating more rough foods or hard objects.” Climate change can be detected by whether the small mammals ate lush greens or hard nuts.

One of the main questions that Belmaker studies is on the Neanderthal extinction and the expansion and survival of modern humans in northern latitudes about 45,000 – 15,000 years ago. Neanderthals are a different species from Homo sapiens, but “every person of European descent has 2-4 percent of Neanderthal DNA” she explained. The pressing question is why Neanderthals became extinct, but humans evolved and successfully adapted to extreme climate changes.

Rat Fossils

The last Glacial Maximum dated to about 25,000 years ago, and it was one of the coldest periods on earth during the past 100,000 years. In the literature, it is known as the Ice Age. To test theories about human survival in harsh climate conditions, Belmaker traveled to two very different ecosystems. The first, in the great steppes of Central Asia and the second the sub-tropics of South China. The climates were undoubtedly different in these two regions, even during the last Glacial Maximum, but just how much? Where did they go to survive the cold?

In Kazakhstan, she joined the excavation of a site named Maibulak about 60 miles west of the city of Almaty. The excavation is run by Radu Iovita, assistant professor of anthropology at New York University. While humans were found before 45,000 years ago and after 16,000 years ago, were they occupying the region during the height of the cold? After meticulously excavating several feet of sediment, no remains were found. Perhaps this is not surprising since the region was so cold, but only few rodent remains were discovered. All could be attributed to those of a Pika, a small mammal related to hares and rabbits that lived in the open steppes. The clear absence of small mammals suggest that it was so cold that even rodents kept their distance from this region.

In South China, Belmaker joined the excavation of a site named Yahuai in the autonomous region of Guangxi. The site is dated to between 45,000 – 15,000 years ago. However, in contrast to Maibulak, this site was chock full of rodent remains. The assemblage comprises several species of flying squirrels and rats, additional mice like rodents as well as shrews and bats. It appears that the region was not as affected by the cold as Central Asia. The cave also had a high density of human artifacts, namely stone tools modified by ancient man, indicating that it was a draw for humans. Was this where the people of Maibulak took retreat during the cold?

People at the digBelmaker is working on the analysis of small mammals from both sites. The remains are on loan here at TU, and she is looking for students to help. She hopes that additional studies may reveal if there was any appreciable climate change in the tropics.

“There is something mystical when you are holding the bone of something that thousands of years old that may have seen or hunted by our ancestors,” Belmaker said.  By studying the climate of older sites, she can discover the biological limits of our species. “If it becomes much warmer, will we be able to survive? Is our technology going to take us through or not? Are humans still evolving?” she asks.

She hopes to bring students to study at Maibulak and Yahuai in the upcoming years in addition to having them work in her lab. “If I can get the students to understand human evolution, then I am ecstatic,” she said.