Ancient North Americans are looking more and more like experienced mammoth killers.

Archaeologists have long debated whether the Clovis people, who lived around 13,000 years ago, had the know-how and technology to regularly hunt the megafauna (SN: 1/11/22). A new chemical analysis suggests that the Clovis diet was indeed dominated by mammoth, scientists report December 4 in Science Advances.

Arguments for whether Clovis people were primarily hunters or foragers have relied on the location of spearheads, tests of reconstructed spears and knowledge of modern foraging behavior. The new dietary analysis provides direct evidence that these ancient people may have relied on mammoths as a food source, supporting claims that they were experienced megafauna hunters.

“It wasn’t a hint of evidence, it was a ‘slap in the face’ of evidence,” says archaeologist James Chatters of McMaster University in Hamilton, Ontario.

Chatters and colleagues, in consultation with Native American tribes, analyzed the remains of the only confirmed Clovis individual — an 18-month-old male called Anzick-1 found in Montana. The team focused on certain forms, or isotopes, of the elements carbon and nitrogen that were deposited from food into his bones. Since the child probably would have been nursing, his isotope values reflected those of his mother, providing clues to her diet.

Teasing out what the mother ate required comparing her calculated dietary isotope values with those found in potential prey species. The researchers then calculated the likely contribution of each species she ate to her overall diet. Mammoths contributed 35 to 40 percent, the team found, with elk, bison and camel contributing much less. Small mammals made up only 4 percent of her intake.

The percentages aren’t a snapshot of a meal but rather reflect at least a year of the woman’s diet, as the isotopes take time to build up in tissues. And since the Clovis people in western North America shared similar behaviors and equipment, it’s probable that others would have had similar diets too, the team says.

“This is not just a single site with a single meal of mammoth,” says coauthor Ben Potter, an archaeologist at the University of Alaska Fairbanks. “This is a tradition of the people.”

Other researchers are more cautious. “It’s certainly a first to see evidence of mammoth in [Clovis] human remains,” which is a “big deal,” says anthropologist Vance Holliday of the University of Arizona in Tucson. But such sweeping assumptions can’t be made from a single skeleton, he says. “I don’t know how you could ever test them unless you found more human remains.”