水中考古学が人類の常識を塗り替える!

最近話題となっているのが最初にアメリカ大陸に渡ったのは誰だったのか?ということです。 氷河期に水深が下がり、ベーリング海峡に出来た陸をアジアから人々が移動したと考えられていましたが、いろいろな説が出ています。特に、今から14000年ほど前にヨーロッパから船を使って北アメリカに到達したという説があります。これはアザラシなどの哺乳類を追ってたどり着いたと言われています。また、太平洋側からもわかめや昆布をたどって北海道からアリューシャン列島を経て、アメリカにたどり着いたと言う説もあります。他にも太平洋をいっきに横断したと言う説もあります。水没遺跡などがどんどん調査されれば水中考古学の発見によっては人類の歴史を大きく塗り替える可能性があるかも知れません。そのうち詳しく記事を書く予定です。

Did first Americans float here or walk?
By LEE BOWMAN
Scripps Howard News Service
February 20, 2006

ST. LOUIS – Generations of schoolbooks have portrayed the arrival of the first modern humans to America as an epic ice-age hike across a land bridge from Siberia to Alaska, then a dash between glaciers covering the west and east of Canada.

But scientists who have devoted much of their careers over the past several decades to better understanding of the peopling of the Americas are increasingly doubtful that the first arrivals only walked into the hemisphere, if they walked at all. Instead, evidence is growing that they paddled, or floated, much of the way, perhaps via the Atlantic as well as the Pacific.

“The coastal-migration theory has yet to be proven with hard evidence, but we have been finding earlier and more widespread evidence for coastal settlement around the Pacific Rim,” said Jon Erlandson, an anthropologist at the University of Oregon who spoke during the annual meeting of the American Association for the Advancement of Science here over the weekend.

In particular, his team shows how migration routes may have followed giant kelp forests growing along Pacific Rim coastlines even in the deepest freeze of the last ice age more than 20,000 years ago.

On the other side of the continent, Dennis Stanford of the Smithsonian Institution’s National Museum of Natural History in Washington over the past decade or so has seen a growing list of archaeological sites from Spain and Britain and from Florida to Virginia to Wisconsin lend support to his theory that bands of sea-mammal hunters living on the edge of Europe reached the New World in numbers sufficient to found colonies 5,000 years or more before any land bridge might have been available.

“The objection has been that people living in the far north couldn’t have gotten across the Atlantic because they didn’t have boats; that they didn’t venture out into the ocean ice. But they did have boats, and if they were anything like those the Eskimos have been using for thousands of years, some of the boats could carry 18-20 adults hundreds of miles,” Stanford said.

The discoveries reflect change in the way researchers are going about studying prehistoric culture, turning to colleagues who have expertise in everything from ancient climate and prehistoric animals to ecologists.

Paleoanthropology has traditionally been mostly about stone tools, particularly blades more or less skillfully flaked into knives, spear points and axes. How a tool was made, and from what sort of material, tells experts a lot about who made it; a little radiocarbon dating of organic material, often charcoal, found around the tools, tells them when they were made, usually within a few hundred years each way.

Until recently, most of the older stone implements found in North and Central America seemed to have been made with the same technique by people dubbed the Clovis culture, for the first material found in New Mexico during the 1930s, and dated back to no more than about 11,500 years ago.

A few sites in Virginia, Pennsylvania and elsewhere that held tools of different styles that seemed to be as much as 10,000 years older had been largely written off, until more old tools coming from layers dating back 14,000, 17,000, even 50,000 years ago started turning up along the East Coast. And diverse sites in South America have yielded artifacts dating to 33,000 years ago, although controversies about methods used to date sites are a staple of the field.

Stanford, who has spent much of his career studying cultures around the Arctic, was among the first to note that spear points and other tools found on the East Coast have a lot in common with points made by a Stone Age culture known as Solutrean, centered in what’s now Southwestern France.

In recent years, he and colleagues have found strong evidence in the form of bones, paintings and other items in coastal caves of Spain that Solutreans used harpoons and boats to go out into icy waters and hunt seals, walrus and auks. And they’ve worked with ancient-climate specialists to establish that sea icepack extended that far south in the Atlantic during the last ice age.

One of the problems in proving this frozen-highway theory in the Atlantic has been that any coastal camps the hunters may have used now lie submerged well out on the continental shelf due to rising sea level. However, Stanford noted that some promising artifacts – along with walrus bones – have turned up recently at new sites around the Chesapeake Bay, for instance.

In the Pacific, Erlandson and many other paleoanthropologists have found and excavated camps of marine hunters at many spots along the coast, particularly offshore islands. What’s been missing is something to connect them as a migration route.

It is known that seafaring people lived at least as far north as Japan at the height of the last glacial period, but a team of marine biologists and other specialists helped Erlandson demonstrate how the fish- and mammal-rich kelp forests ran in an arch all the way from the Kurile Islands to Alaska and along all or most of the Pacific Coast. The kelp beds not only ensured food, but also could have helped protect small boats from big waves and served as mooring points.

“The fact that these productive kelp forests are found adjacent to some of the earliest coastal archaeological sites in the Americas really enhances the argument that the first Americans didn’t walk here, they floated. In essence, they may have utilized a sort of kelp highway,” Erlandson said.

On the Net: www.aaas.org
http://www.knoxstudio.com/shns/story.cfm?pk=FIRSTAMERICANS-02-20-06&cat=AN

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ST. LOUIS—The first humans to spread across North America may have been seal hunters from France and Spain.

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This runs counter to the long-held belief that the first human entry into the Americas was a crossing of a land-ice bridge that spanned the Bering Strait about 13,500 years ago.

The new thinking was outlined here Sunday at the annual meeting of the American Association for the Advancement of Science.

The tools don’t match

Recent studies have suggested that the glaciers that helped form the bridge connecting Siberia and Alaska began receding around 17,000 to 13,000 years ago, leaving very little chance that people walked from one continent to the other.

Also, when archaeologist Dennis Stanford of the Smithsonian Institution places American spearheads, called Clovis points, side-by-side with Siberian points, he sees a divergence of many characteristics.

Instead, Stanford said today, Clovis points match up much closer with Solutrean style tools, which researchers date to about 19,000 years ago. This suggests that the American people making Clovis points made Solutrean points before that.

There’s just one problem with this hypothesis—Solutrean toolmakers lived in France and Spain. Scientists know of no land-ice bridge that spanned that entire gap.

The lost hunting party

Stanford has an idea for how humans crossed the Atlantic, though—boats. Art from that era indicates that Solutrean populations in northern Spain were hunting marine animals, such as seals, walrus, and tuna.

They may have even made their way into the floating ice chunks that unite immense harp seal populations in Canada and Europe each year. Four million seals, Stanford said, would look like a pretty good meal to hungry European hunters, who might have ventured into the ice flows much the same way that the Inuit in Alaska and Greenland do today.

Inuit use large, open hunting boats constructed from animal skins for longer trips or big hunts. These boats, called umiaq, can hold a dozen adults, as well as several children, dead seals or walruses, and even dog-sled teams. Inuit have been building these boats for thousands of years, and Stanford believes that Solutrean people may have used a similar design.

It’s possible that some groups of these hunters ventured out as far as Iceland, where they may have gotten caught up in the prevailing currents and were carried to North America.

“You get three boats loaded up like this and you would have a viable population,” Stanford said. “You could actually get a whole bunch of people washing up on Nova Scotia.”

Some scientists believe that the Solutrean peoples were responsible for much of the cave art in Europe. Opponents of Stanford’s work ask why, then, would these people stop producing art once they made it to North America?

“I don’t know,” Stanford said. “But you’re looking at a long distance inland, 100 miles or so, before they would get to caves to do art in.”
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