In 2015, scientists released the results of DNA research conducted on a set of remains from Washington state popularly known as Kennewick Man. That ancient American lived more than 9,000 years ago, close to the era of Nevada’s Spirit Cave Man.

Some of the oldest sets of Paleo-Indian remains have been found in the West. The Great Basin, particularly Nevada, has yielded human remains that Carbon-14 tests indicate are much older than 10,000 years before the present. Kennewick Man, found in 1996, and Spirit Cave Man, whose antiquity was determined in 1994, generated much publicity. That’s partly because artists have created busts of their likenesses. Some anthropologists have argued that because both sets of ancient remains appear so anatomically different from modern American Indians, they might represent a population already established in North America when the ancestors of the modern Indians arrived.

Scientists hypothesized that those ancient people may have originated from the Pacific Rim and reached North America by boat, or migrated across an ice sheet from Europe long before ancestors of the modern tribes crossed the Bering Strait.

The 2015 analysis of Kennewick Man showed that his genome is more closely related to modern tribal people than any other groups of humans tested. It wasn’t possible to directly link him to any modern tribe, scientists concluded, and he may be even more related to some other group of Native Americans who haven’t had their DNA collected. Researchers also tested the DNA of another ancient set of remains – a 12,600-year-old skeleton dubbed the Anzick Child -- found in Montana. The Montana remains appear to belong to another branch of Native Americans who spread south into Central and South America thousands of years ago.

Scientists now theorize that several migrations of people came into the New World in ancient times. Kennewick Man’s ancestors may have populated the northern part of the continent. The descendants of the Anzick Child’s people also came from Asia and pressed on into South America. Then, about 4,000 years ago, other waves of migration came to the New World, one of them giving rise to the Inuit/Eskimo people.

No tests have been done on Spirit Cave Man, but more DNA analysis may shed light on theories about where the first residents of North America came from and who they became. The recent genome research, while significant, raises even more questions about the peopling of the continent. Scientists speculate that if and when answers are found they may be more complex than anyone ever imagined.