The Washington Post
First Americans linked to Jomon
WASHINGTON Ancient peoples only loosely related to modern Asians crossed the Arctic land bridge to settle America about 15,000 years ago, according to a study offering new evidence that the Western Hemisphere hosted a more genetically diverse population at a much earlier time than previously thought.
The early immigrants most closely resembled the prehistoric Jomon people of Japan and their closest modern descendants, the Ainu, from the island of Hokkaido, the study says. The Jomon and Ainu have skull and facial characteristics more genetically similar to those of Europeans than to mainland Asians.
The immigrants settled throughout the hemisphere and were in place when a second migration from mainland Asia came across the Bering Strait beginning 5,000 years ago and swept southward as far as modern-day Arizona and New Mexico, the study says. The second migration is the genetic origin of today's Eskimos and Aleuts, as well as the Navajos of the U.S.
The study, which was published in Tuesday's edition of the Proceedings of the National Academy of Sciences, adds new evidence to help settle one of anthropology's most contentious debates: Who were the first Americans? And when did they come?
"When this has been done before, it's been done from one point of view," said University of Michigan physical anthropologist C. Loring Brace, who led the team of researchers from the United States, China and Mongolia that wrote the new report. "We try to put together more dimensions."
For decades, anthropologists' dogma held that the Americas were populated after one migration from Asia around 11,200 years ago the supposed age of the earliest of the elegantly crafted, grooved arrowheads first found in the 1930s at Clovis, N.M.
By the end of the 1990s, however, the weight of evidence had pushed the date of the first arrivals back several thousand years. A site at Cactus Hill, near Richmond, Va., may be 17,000 years old. In Chile, scientists excavating a 12,500-year-old settlement at Monte Verde have found evidence of a human presence that may extend back as far as 30,000 years.
But as the migration timetable slipped, additional questions and controversies have arisen. The 1996 discovery in Kennewick, Wash., of the nearly complete skeleton of a 9,300-year-old man with "apparently Caucasoid" features stimulated interest in the possibility of two or more migrations including a possible influx from Europe.
The new study attempted to answer this question by comparing 21 skull and facial characteristics from more than 10,000 ancient and modern populations in the Western Hemisphere and Old World.
The findings provide strong new evidence supporting earlier work suggesting that ancient Americans, like "Kennewick Man," were descended from the Jomon, who walked from Japan to the Asian mainland and eventually to the Western Hemisphere on land bridges as the Earth began to warm up about 15,000 years ago at the end of the last ice age.
Brace described these early immigrants as "hunters and gatherers" following herds of mastodon, first into North America, and eventually spreading throughout the hemisphere. Because the North in Siberia and Canada was still extremely cold, only a limited number of people could make the trek and survive.
So immigration slowed, Brace said, for about 10 millennia. Then, about 5,000 years ago, agriculture developed on mainland Asia, enabling people to grow, store and carry food in more inhospitable areas. Movement resumed, but the newcomers were genetically Asians "distinct racially" from the first wave, Brace added.
The second wave spread across what is now Canada and came southward, cohabiting with the earlier settlers and eventually creating the hybrid population found by the Spaniards in the 15th century.
While many researchers agree on the likelihood of two migrations, their timing and origin are matters of dispute. Brace's team suggests that both movements occurred after the last ice age began to moderate between 14,000 and 15,000 years ago.
But University of Pennsylvania molecular anthropologist Theodore Schurr said genetic data of American populations suggest that humans may have been in the Western Hemisphere much earlier 25,000 to 30,000 years ago.
This would mean that the first wave came before the so-called "glacial maximum," between 14,000 and 20,000 years ago, when the ice age was at its fiercest and "human movement was practically impossible." Schurr said. "Were there people here before the last glacial maximum?" he asked. "The suggestion is, yes."
To date, however, archaeological evidence for settlements earlier than 20,000 years ago is almost nonexistent, but Schurr suggested that researchers may have been reluctant to explore layers older than Clovis because of Clovis' predominance in the scientific community.
Still, neither Brace nor Schurr were prepared to endorse the view propounded by the National Museum of Natural History's Dennis Stanford: that at least some immigrants may have come from ice age Europe.
"The environment in Europe was so harsh that land mammals were very rare," Stanford said, "so they went to the beach."
If these ancient people had boats, it was natural that they should go to sea to look for food, and edging farther north and west, they would eventually reach the fish-rich Grand Banks.
"From there they move right down the east coast" of North America.
Stanford bases his theory on the presence of Clovis-like artifacts on the Iberian Peninsula around 20,000 years ago, and that there are more Clovis points in the eastern U.S. than in the West.
Also, he notes that genetic evidence links eastern Native American populations with ancient Europeans, but not with Asians.