Pause Is Seen in a Continent’s Peopling

Beringia map, courtesy of Illinois State Museum
Beringia map, courtesy of Illinois State Museum

The New York Times




Using a new method for exploring ancient relationships among languages, linguists have found evidence further illuminating the peopling of North America about 14,000 years ago. Their findings follow a recent proposal that the ancestors of Native Americans were marooned for some 15,000 years on a now sunken plain before they reached North America.

This idea, known as the Beringian standstill hypothesis, has been developed by geneticists and archaeologists over the last seven years. It holds that the ancestors of Native Americans did not trek directly across the land bridge that joined Siberia to Alaska until the end of the last ice age, 10,000 years ago. Rather, geneticists say, these ancestors must have lived in isolation for some 15,000 years to accumulate the amount of DNA mutations now seen specifically in Native Americans.

Archaeologists examining deep sea cores from the Bering Strait believe that a special ecological zone known as shrub tundra existed there during the Last Glacial Maximum, an exceptionally cold period that lasted from about 30,000 to 15,000 years ago. Though often referred to as a bridge, the now sunken region, known as Beringia, was in fact a broad plain. It was also relatively warm, and supported trees such as spruce and birch, as well as grazing animals.

Writing in the journal Science last month, John F. Hoffecker, an archaeologist at the University of Colorado, summarized the evidence for thinking the Beringian plain was the refuge for the ancestral Native American population identified by the geneticists. “The shrub tundra zone in central Beringia represents the most plausible home for the isolated standstill population,” he and colleagues wrote.

Dr. Hoffecker believes that the ancestral Native Americans could have kept warm with fires of animal bones and wood, and that their range was restricted by the availability of wood. “The paleoecological data is consistent with the idea of a refugium, and the wood might be a key variable,” he said in an interview.

Linguists have until now been unable to contribute to this synthesis of genetic and archaeological data. The first migrations to North America occurred between 15,000 and 10,000 years ago, but most linguists have long believed that language trees cannot be reconstructed back further than 8,500 years. Vocabulary changes so fast that the signal of relationship between two languages is soon swamped by the noise of borrowed words and fortuitous resemblances.

But in 2008, Edward Vajda, a linguist at Western Washington University, said he had documented a relationship between Yeniseian, a group of mostly extinct languages spoken along the Yenisei River in central Siberia, and Na-Dene.

The Na-Dene languages are spoken in Alaska and western Canada, with two outliers in the American Southwest, Navajo and Apache. His assertion that the two families of languages had descended from a common tongue implied that he was seeing back in time at least 12,000 years or so, to the arrival of Na-Dene speakers in North America.

Many linguists accepted Dr. Vajda’s analysis, despite its time depth. He relied heavily on structural features of language, which turn out to be more resistant to change than vocabulary. In particular, he looked at Yeniseian and Na-Dene verbs, since languages in both groups have a template of fixed positions before and after the verb for specifying various attributes.

Building on Dr. Vajda’s success, two linguists, Mark A. Sicoli of Georgetown University and Gary Holton of the University of Alaska, have assessed the relationship of the two language families based on shared grammatical features, rather than vocabulary.

In a paper published in the journal PLoS One on Wednesday, they report their surprising finding that Na-Dene is not a descendant of Yeniseian, as would be expected if the Yeniseian speakers in Siberia were the source population of the Na-Dene migration. Rather, they say, both language families are descendants of some lost mother tongue. Their explanation is that this lost language was spoken in Beringia, and that its speakers migrated both east and west. The eastward group reached North America and became the Na-Dene speakers, while the westward group returned to Siberia and settled along the Yenisei River.

The Na-Dene migration from Beringia came after the main migration of 15,000 years ago, but the relationship between the two populations remains to be settled. “There may have been multiple streams of people moving out of that single source at different times,” said Dennis H. O’Rourke, an anthropological geneticist at the University of Utah.

If Yeniseian represents a return migration from Beringia, the question of the source population in Siberia of Native Americans is thrust back into obscurity. “If Yeniseian is off the table as a back-migration, there is no other candidate,” Dr. Sicoli said.

Several Yeniseian languages are known only from czarist fur tax records. Pumpokol, Arin, Assan and Kott have not been spoken for two centuries. The only surviving language, Ket, has fewer than 200 living speakers.


30,000 year old Brazilian artifacts throw wrench in theory humans first arrived in Americas 12,000 years ago



By Agence France-Presse
October 9, 2013

It’s no secret humans have been having sex for millennia — but recently discovered cave art suggests they were doing it in the Americas much earlier than many archeologists believed.

A new exhibit in Brazil showcases artifacts dating as far back as 30,000 years ago — throwing a wrench in the commonly held theory humans first crossed to the Americas from Asia a mere 12,000 years ago.

The 100 items on display in Brasilia, including cave paintings and ceramic art, depict animals, ceremonies, hunting expeditions — and even scenes from the sex lives of this ancient group of early Americans.

The artifacts come from the Serra da Capivara national park in Brazil’s northeastern Piaui state, on the border of the Amazon and Atlantic Forests, which attracted the hunter-gatherer civilization that left behind this hoard of local art.

Since the 1970s, Franco-Brazilian archaeologist Niede Guidon has headed a mission to carry out large-scale excavation of Piaui’s interior.

“It’s difficult to think there exists a site anywhere with a higher concentration of cave art,” the 80-year-old Guidon told AFP.

Many paths led to Americas

Other traces of the civilization include charcoal remains of structured fires, explained Guidon, who hails from Sao Paulo.

“To date, these are the oldest traces” of human existence in the Americas, she emphasized.

The widely held theory has suggested human beings only reached the Americas some 12,000 years ago from Asia, crossing the Bering Strait to reach Alaska.

Some archeologists contend flaked pebbles at the Brazilian sites are not evidence of a crude, human-made fire hearth made some 40 millennia ago, but are rather geofacts — a natural stone formation, not a man-made one.

But Guidon said she believes the Serra dwellers may have come originally from Africa, and she said the cave art provides compelling evidence of early human activity.

The paintings are estimated to date back some 29,000 years, she said, noting: “When it began in Europe and Africa, it did here too.”

Other sites, including Valsequillo in Mexico and Monte Verde in Chile, also indicate the presence of communities tens of thousands of years ago.

These sites have led archeologists to speculate that peoples traveled various routes to reach the Americas and at different stages, archeologist Gisele Daltrini Felice told AFP.

In search of tourists

UNESCO conferred World Heritage status on the Serra da Capivara in 1991, but tourists remain thin on the ground, which frustrates Guidon.

“After putting in a great amount of effort (to promote the site) we are up to 20,000 visitors a year,” the archeologist said.

But “World Heritage sites get millions, and we are prepared to receive millions,” she added.

The interior of the Piaui region is marked by widespread poverty, which has much to gain from tourism, Guidon stressed.

But resources are lacking to promote the attractions in a remote corner of the giant nation, she said. The nearest city is the modest town of Sao Raimundo Nonato, which has spent years trying to have an airport built.

The EU is promoting both the new exhibit as well as a swath of conferences on the area under the auspices of UNESCO, Brazil’s Institute of Parks and the country’s Institute of Historic and Artistic Heritage.

“The idea is to promote cultural, historic and nature-based tourism in order to aid the development of areas adjoining Brazil’s major parks — and especially the Serra da Capivara, which has the most modern infrastructure,” with 172 sites to visit, said Jerome Poussielgue, European Union cooperation and development officer for Brazil.

And the foundation behind research into the park is backing development projects — including a ceramics factory that reproduces images of the cave art, a program aimed at giving local women work experience.

“We would like to help in the development of a region where women suffer hugely from violence,” says Guidon.