A burnt olive tree has helped to resolve a controversy over dating key events in the Mediterranean that took place more than three millennia ago.

The new dates would change the chronology of the Minoans, Greeks, Cypriots and others by a century and question Egyptian chronology and the genesis of Classical civilisation.

The rewriting of the history of the Aegean has come, in part, from a study of charcoal and seed samples from sites dated to between 1700BC and 1400BC, and a single olive tree.

The gnarled stump was found in a volcanic rock layer on the Greek island of Santorini (Thera). During the second millennium BC, it was the site of an eruption that buried thriving civilisations, including Crete's famed Minoans.

Researchers reported in the journal Science that they can now tell when this eruption occurred, how old these Bronze Age cultures were and how they were connected to other cultures in Egypt and the Gulf.

Archaeologists and scientists have been trying to solve this culture-linking problem for decades. A decisive carbon-dating technique has been reported by a team led by Dr Sturt Manning of Cornell University. They implemented the theories of Thomas Bayes, (1702-1761) an English cleric and mathematician.

This work is backed by a study by a team led by Dr Walter Friedrich of the University of Aarhus in Denmark. The radiocarbon dating was done at Oxford, Vienna and Heidelberg, and the software implementing Bayes' theories used by both teams was developed at Oxford University by Dr Christopher Bronk Ramsey.

The eruption of Santorini offers an important reference point. Because of the way the branches and bark were preserved, researchers knew the tree had been buried alive. This gave the researchers a rare opportunity to work out the age of the eruption, because trees form new rings each year as they grow. As the tree was still growing when the volcano exploded, the newest ring would be almost exactly the same age as the eruption.

The researchers used radiocarbon dating to work out the ages of the tree rings and learned that the eruption was between 1627BC and 1600BC. This is a century earlier than some archaeologists had thought.

That means that many of the cultures that researchers once assumed were trading with each other, may have existed at different times. Researchers have thought that the civilisations on the islands of Crete, Cyprus and in Greece had many ties to Egypt.

But the new timeline indicates that these civilisations may have been more tightly linked with cultures of the Levant, which today includes Israel, Lebanon and Syria. The cultures were contemporaneous with Egypt's Second Intermediate Period — when northern Egypt was controlled by a Canaanite dynasty with links to the Levant — instead of the subsequent New Kingdom.

Before the study, the New Palace culture on Crete, an influence on ancient Greek civilisation, had been linked to the New Kingdom period in Egypt. But since the 1970s, radiocarbon dates have indicated that the New Palace period and others in the Aegean — including the Shaft Grave period of mainland Greece and the period that saw the development of new coastal sites on Cyprus — may have been older.

Until recently, there was enough uncertainty in the radiocarbon data to keep this chronology open to debate.

Egyptologist Manfred Bietak of the University of Vienna is one proponent of the late chronology who is sticking to his guns. "I am not impressed," he told Science.