|25 August 2011
Human precursors went to sea
A team of researchers including North Carolina State University (USA) geologist Karl Wegmann found evidence that our ancestors were crossing open water more than 100,000 years earlier than scientists had previously thought. Their evidence is based on stone tools from the island of Crete (Greece). Because Crete has been an island for eons, any prehistoric people who left tools behind would have had to cross open water to get there.
The tools are so old they predate the human species, said Thomas Strasser, an archaeologist from Providence College who led the team. They were made by our ancestors, Homo erectus. The tools are very different from any others found on Crete, Strasser said, adding they're most similar to early stone-age tools from Africa that are about 700,000 years old. A few of the stone tools were embedded in rocks formed from ancient beach sands, hundreds of feet above the present shoreline. The colliding African and Eurasian tectonic plates that drive the region's strong earthquakes are pushing Crete upward out of the sea.
Once geologists know the age of lower terraces (50,000 years - the limit for carbon dating) and the rate at which the land is rising, they calculate the age of higher terraces by measuring the difference in elevation. In this case a record-smashing 130,000 years old.
Edited from Physorg.com (17 August 2011)
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