University of Minnesota students and hyenas at the Milwaukee County Zoo are stripping meat from bones to replicate and study prehistoric behavior.

University anthropology graduate student Katrina Yezzi-Woodley cleans, processes and analyzes bone fragments broken by hyena teeth and human-made stone tools. She’s enlisted help from 14 undergraduate and graduate students in a zoo archeology course to classify markings on bones, which help archaeologists identify where hunter-gatherers once lived.

“Early humans took stone to get marrow [from bones],” Woodley said. “But we didn’t witness what happened back then.”

Woodley uses a 3-D model to determine whether the breaks came from hyena bites or stone tools, said Martha Tappen, associate anthropology professor and instructor of the course.

“We’re trying to determine, without a doubt, who accumulated the bones,” she said.

During an annual paleolithic picnic in mid-October, students in the course made stone tools called flakes and used them to butcher a dead animal — typically deer or elk from local farms.

“It’s really a group activity … we tend to think of butchering as, you have a butcher and he does it somehow all on his own,” said anthropology student Jesse Ehrenreich.

Amber Jaeger, an anthropology junior, said she knew little about animal bones before taking the course.

“The next time I’m in the field I can have a better sense of bones,” Jaeger said. “And I think for someone who is not even an anthropologist, we’re learning about how animals work.”

Students also reconstructed other types of prehistoric human behavior at the picnic, like spear throwing and archery.

Meanwhile, two hyenas at the Milwaukee County Zoo chomp on bones like their ancestors did.

It only takes the hyenas 10 to 15 minutes to tear elk thigh bones apart, said Tim Wild, curator of large mammals at the zoo.

Unlike other mammals, hyenas are able to tear the bones apart and digest some of them, Wild said.

Hyenas are known as scavengers but “are also serious hunters in their own right,” Wild said. Hyenas typically hunt antelope and warthogs, but they occasionally target larger game, like zebras.

“When the hyenas get done with the bones, there are usually just small shards, five to six inches at the most,” he said. “There’s not a whole lot left.”

Workers at the zoo salvage the fragments and save them for Woodley to pick up and process.

Students simmer the bones in a crockpot and use wooden tools to scrape off remaining meat, Ehrenreich said. Adding this step can take more than 10 hours.

Woodley will use white light scanners to make 3-D images of the bones at a newly opened laboratory in Heller Hall by January.

These machines cast light in multiple directions onto the bone and let the user zoom in closely to examine small markings, Woodley said.

Her analysis would help researchers like Tappen identify who the hunter-gatherers were and who scavenged bones found at archaeological sites.