Oct. 13 (UPI) -- While theories have long held that Indigenous Americans are descended from people who migrated north from Japan, new research suggests that the earliest inhabitants of the Americas were descended from people in Siberia and Beringia.
Stone tools at several of the earliest known archaeological sites inhabited by North America's first peoples look a lot like those used 15,000 years ago by the Jomon people, early inhabitants of Japan.
Parallels between archaeological materials on both sides of the Pacific have inspired a few archaeologists to claim at least some of North America's earliest inhabitants migrated from Japan.
New research, however, has splashed cold water on the out-of-Japan hypothesis. According to the study, the earliest Native Americans and the Jomon people were biologically and genetically dissimilar.
The new findings, published Wednesday in the journal PaleoAmerica, relied on biological distance analysis, the study of similarities and differences between biological traits among various groups of people, ancient and modern.
Comparing ancient teeth
For the new findings, scientists measured the form and structure -- called morphology -- of thousands of teeth collected from archaeological sites in the Americas, Asia, Australia and the Pacific Islands.
The measurements used for the study had been collected and organized, amassed over decades, but the survey utilized a new algorithm.
"It's a program that was developed by a doctoral student in Portugal," study lead author Richard Scott told UPI.
"It is basically a Bayesian algorithm designed to calculate the probability that an individual demonstrates the morphological characteristics of one of the five geno-geographic groups -- East Asian, American Arctic, non-Arctic American, Southeast Asian and Austral-Melanesian," said Scott, a professor of anthropology at the University of Nevada-Reno.
The analysis showed the teeth of ancient Jomon people and those of the earliest known inhabitants of North America were not very alike. Instead, the data revealed affinities between the teeth of ancient Siberian populations and those of the Indigenous Americans
"Our work pretty much falls in line with the Beringian Standstill hypothesis," Scott said.
The Beringian Standstill theory posits that a group of people from Siberian Asia arrived in Beringia about 25,000 years ago.
Beringia is the name for the massive land bridge that connected what now is Alaska and Russia during the Last Glacial Maximum, when sea levels were significantly lower than they are today.
As the theory goes, the people of Beringia began to migrate south, populating the Americas, about 15,000 years ago.
But while the latest analysis reinforced the links between the ancient peoples of Siberia, Beringia and North America, Scott's findings also showed that the earliest Native Americans were a lot more like one another than people of Asia.
2,000 years of isolation
"The Native American samples stood alone. What seems to have happened is these populations got isolated up in Beringia and differentiated from each other for 8,000 to 10,000 years," Scott said. "All of the Americans shared a common ancestor."
Of course, the Beringian Standstill isn't the only explanation for the peopling the Americas, and teeth aren't the only biological materials available for analysis.
Supporters of the out-of-Japan hypothesis and other alternative explanations for the peopling of the Americas have sometimes used craniometric analyses, the study of skull morphologies, to support their theories. However, craniometric surveys have also produced divergent conclusions.
"Fundamentally, cranial morphology is a very complex, multifactorial character with many sources of variation, e.g., underlying genetic variation, multiple environmental sources of variation, different developmental patterns, etc.," study co-author Dennis O'Rourke, professor of anthropology at the University of Kansas, told UPI in an email.
Scott prefers the insights provided by teeth.
"Teeth are much more conservative, they don't change much over time," Scott said. "They change some, but not a lot."
In other words, the teeth of ancestral populations are a lot more like those of their descendants than their skulls.
Scott, who calls himself a specialist -- "I'm a tooth guy" -- said that the best theories are those supported by multiple lines of evidence.
In the newly published paper, genomic surveys showing strong genetic links between the ancient populations of Siberia and Indigenous Americans corroborate Scott's findings.
O'Rourke and his fellow geneticists found no overlap between the maternal and paternal lineages of early Jomon and American populations.
Though the Beringian Standstill hypothesis continues to gain momentum, the theory isn't ironclad. Just last month, scientists published an analysis of ancient footprints found in New Mexico that suggested humans were in North America at least 23,000 years ago.
"There are many unresolved questions, including: When did people first arrive in the Western Hemisphere? What route did the first people take to move south beyond the ice sheets of the Last Glacial Maximum and how rapidly did they disperse into the continents?" O'Rourke said.
"None of these are particularly new and have been the focus of research for some time. New discoveries in archaeology and genomic analyses refine the way in which we continue to address such questions," he said.
Native Americans are where they are
While questions about the peopling of the Americas continue to befuddle and inspire both archaeologists and anthropologists, Scott said leaders and scholars among Native American groups are uninterested in pursuing questions about where Indigenous Americans came from.
"They all have their own origin stories," Scott said.
As far as most Native Americans are concerned, they've always been where they are.
"The peopling of the Americas is a white person's problem, because indigenous people already understand it," Charles Riggs, an anthropologist at Fort Lewis College in Colorado, told UPI.
"That's not suggest that indigenous peoples are anti-science. They appreciate being brought into the process, but they don't appreciate being told things about their past by people that have oppressed them for hundreds of years," Riggs said.
Riggs, who wasn't involved in the newly published research, said it's not correct that indigenous people are uninterested in archaeology. In fact, native groups and scholars are increasingly involved in archaeological investigations.
"But it's a very different kind of community-based archaeology, asserting their rights to land and water -- reinforcing that connection to place," Riggs said.
"I think at some point we just have to accept that questions about the peopling of the Americas are our questions and our questions alone, and you just aren't going to get buy-in."