Investigating Ice Age America’s Ancient Abattoir

This article is from Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.

During the last Ice Age, woolly mammoths, bison, caribou, and herds of shaggy, burly horses roamed the tundra-like grasslands of Beringia—a now-flooded landmass that once connected Siberia to Alaska and the Yukon—eating the vegetation and running from predators such as steppe lions, bears and wolves. Also at this time people lived and hunted in Beringia. At the Bluefish Caves, three caves in a remote limestone ridge in northern Yukon, archaeologists have unearthed some of the oldest known signs of human habitation in North America. Today, these caves offer scientists a glimpse into the lives of the Beringian hunters who used them almost 24,000 years ago.

Archaeologists have long debated how and when humans entered the Americas. Throughout the 20th century, the mainstream hypothesis has been that the Clovis people first arrived in Alaska about 13,000 years ago. Archaeologists who presented earlier dates for the arrival of humans were dismissed by many of their peers, and the sites they examined were ignored.

One of the archaeologists whose life’s work has been all but overlooked was Jacques Cinq-Mars, a Canadian archaeologist who worked for the Canadian Museum of History in Quebec. During his excavations between 1977 and 1987 in the Bluefish Caves on Van Tat Gwich’in First Nation territory in the northwestern Yukon, Cinq-Mars uncovered evidence that the Clovis were not the first to set foot in the Americas. Through his research, he concluded that hunters used the site around 24,000 years ago. But Cinq-Mars, who died in November 2021, was met with skepticism, and his findings were questioned for decades.

Today, the first Clovis model is obsolete among most archaeologists, and older sites are generally accepted. But the commitment of some archaeologists to the hypothesis means the field now has significant catching up to do.

The work of University of Kansas archaeologist Lauriane Bourgeon examining bones unearthed in the Bluefish Caves is expanding scientists’ understanding of how people lived in what is now the Yukon 24,000 years ago. Bobbi Estabrook/Courtesy of Hakai Magazine

An example of this ongoing rectification is the work of Lauriane Bourgeon, a French archaeologist at the University of Kansas. Bourgeon has spent much of her career reexamining and dating the Bluefish Caves collection – which includes a small number of tools and 36,000 animal bones – to clarify the history of the disputed site.

For example, their research has shown that at least 15 bones from the Bluefish Caves were cut-marked by humans as early as 23,500 years ago. Man-made cuts, she explains, are deep and thin with a V-shaped profile and typically correspond to strategic slaughter. The oldest bone in the Bluefish Caves collection, such as a 23,500-year-old horse jaw, has long, straight cuts on the inside consistent with efforts to remove muscle.

Having already corroborated Cinq-Mars’ claims that humans used the Bluefish Caves so long ago, Bourgeon has shifted the scope of her work: now she’s trying to figure out what they were doing there.

Bourgeon’s examination of the Bluefish Caves collection shows that most of the bones are from Beringian or Yukon horses. These furry animals were smaller than modern horses and likely roamed in herds of one male and many females. The Beringian horse went extinct about 14,000 years ago, possibly due to human pressure and climate change, she says.

That most bones come from healthy adult horses is “typical of human hunting,” according to Bourgeon — in contrast, carnivores typically target vulnerable individuals. The cavities are also unusually full of pelvis and other heavy bones. Based on this, along with the small number of stone tools and the lack of a fireplace, Bourgeon and her colleague Ariane Burke from the University of Montreal in Quebec argue that the Bluefish Caves were most likely used as a temporary camp by hunters primarily targeting Beringian horses.

Much of Beringia was submerged by rising seas after the last Ice Age, submerging much evidence of human movement across the landmass. Mark Garrison/Courtesy of Hakai Magazine

These Ice Age hunters, Bourgeon explains, would have carried the horse carcasses to the caves to be slaughtered there. They would strategically strip the flesh and marrow from the largest bones and leave them behind as they made the trek back to a residential camp.

Brandon Kyikavichik, a Van Tat Gwich’in heritage researcher who translates oral history, says Bourgeon’s interpretation of the caves’ use “makes a lot of sense based on his knowledge of traditional hunting practices and the lives of his ancestors during the last Ice Age.”

“The country was very different” when hunters used the Bluefish Caves, explains Kyikavichik. At that time, he says, his ancestors were being tormented by giant animals. That is, until a hero known to the Van Tat Gwich’in as Ch’ataiiyuukii came from the ocean and “made the world more hospitable to humans,” explains Kyikavichik. Ch’ataiiyuukii became a leader and taught the Van Tat Gwich’in how to map the stars and predict animal behavior. Then, according to one story, Ch’ataiiyuukii floated up and became a constellation.

“Our history is rich,” says Kyikavichik. “It goes back thousands of years [and] the stories are told with passion.” He notes that the Van Tat Gwich’in have always been involved in archaeological work in the area and their history could help identify sites for future digs.

However, finding physical evidence of the small human population that inhabited Beringia during the last Ice Age is a challenge. The people were probably nomadic and most of the land is now underwater. Although “the human signal is very weak in the Bluefish Caves,” says Bourgeon, it was clear that humans had been there several times.

The Bluefish Caves in northwestern Yukon photographed in the early 1980s by archaeologist Jacques Cinq-Mars, the first western explorer to recognize the site’s importance. Jacques Cinq-Mars/ Courtesy Canadian Museum of History, IMG2014-0109-0002-Dm. Used with permission.

Bourgeon plans to conduct further excavations at the site. She is also in the process of confirming that the layers of sediment in the caves are indeed in chronological order, as postulated by Cinq-Mars. “If I can… give a relative age for the stone tools, Bluefish Caves might be better accepted by the scientific community,” says Bourgeon.

Tom Dillehay, an archaeologist at Vanderbilt University in Tennessee who wasn’t involved with the study, says that while questions still remain about the Bluefish Caves, the evidence of human activity is becoming “more and more compelling.”

He wants to see confirmation that the layers of soil in the caves have not been disturbed, as well as further excavation at the site to obtain indisputable evidence of human presence. While most caves have been destroyed to some degree by natural or human causes, he’s always believed that some sections of the Bluefish Caves floor appear relatively intact and that the radiocarbon dates are reliable, says Dillehay.

Like Cinq-Mars, Dillehay encountered opposition from archaeologists who favored the first Clovis hypothesis in the late 1970s when he presented data from Monte Verde, a pre-Clovis archaeological site in Chile. “I was surprised at how intense it got,” he says. Even today, with the first Clovis model largely falling out of favor, there are still some who are vocal in defending it, he adds.

Dillehay remembers Cinq-Mars as “a sincere and dedicated scientist” who left a legacy of patience.

Bourgeon began her research at the Bluefish Caves believing that there were no humans in North America during the last ice age, but quickly realized that Cinq-Mars was right. Though she only met him a couple of times and wished she had had more opportunity to speak to him before his death, Bourgeon is glad he lived to see her efforts validate his research.

“I wish I had known him better,” says Bourgeon. “It’s always nice to spend time with an archaeologist who is as good as he is.”