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Scientists say they have found a way to precisely date ancient wood from the eastern Mediterranean, a technique that could rewrite the history of the Greeks, the Egyptians and other civilizations.

Among other things, the technique - a 1,503-year guide to tree-ring patterns - moves back by about a century the start of the Aegean Late Bronze Age, when the Minoans were at their most powerful on the island of Crete.The work was reported in Thursday's issue of the journal Nature by researchers including Peter Kuniholm of Cornell University in Ithaca, N.Y., and Sturt Manning of the University of Reading in England.

They said they can provide precise dates for wood that was chopped down between 2220 B.C. and 718 B.C.

The new work is extremely important, said Aslihan Yener, an archaeologist at the University of Chicago who was not involved in the project.

By helping scientists synchronize the chronologies they have constructed for ancient cultures, it will alter modern understanding of trade, migrations, wars and other relationships between civilizations in the region, she said.

And the greater precision on historical dates will clarify understanding of social and political changes within civilizations, she said.

The researchers immediately dated some 22 ancient sites, including a huge mound in Turkey that may be the tomb of King Midas. Timbers from a structure inside the mound that Manning called the oldest standing wooden building in the world were from trees cut down in 718 B.C., the researcher said.

Similarly, wood found in a shipwreck that contained a gold scarab inscribed with Egyptian queen Nefertiti's name can now be dated to 1316 B.C., he said. The jewelry would not have been made until Nefertiti was queen, so it shows she had taken the throne by then, he said. That confirms standard Egyptian chronology and rules out some challenges, Manning said.

The work also gives new evidence that a major volcanic eruption on the Aegean island of Thera, also called Santorini, happened in 1628 B.C. rather than around 1500 B.C., as most existing scholarship said. That in turn would move back the start of the Aegean Late Bronze Age.

It would also move back the timing of the Late Bronze Age on Cyprus, because a Cypriot bowl from that period was found on Thera buried under the eruption debris, Manning said.

Yener, noting the 128-year shift in the date of the volcanic eruption, said that being wrong by that much would be like trying to understand America under Ulysses S. Grant "with the assumption that Russia was ruled by Yeltsin."

The researchers worked with samples of ancient wood found at 22 sites in Turkey. They studied year-to-year variations in the width of the annual tree rings, which are influenced by climate changes. If a particular pattern of changes showed up in two wood samples, it meant the trees had been growing during the same years.

In this way, the researchers built up a tree-ring pattern covering 1,503 consecutive years. They determined the dates covered by analyzing radioactive carbon in the wood and matching two blips in the pattern to two volcanic eruptions.

The biggest growth spurt appears to coincide with a tree-ring aberration seen in Europe and the United States that is known to have happened in 1628 B.C. or 1627 B.C., they said. They propose that it was caused by the volcanic eruption on Thera.

A second aberration 470 years later matches one known from 1159 B.C. in European tree rings, caused by a volcanic eruption in Iceland, the researchers said.