Footprints of 'first Americans'

Human settlers made it to the Americas 30,000 years earlier than previously thought, according to new evidence.

British scientists came to this controversial conclusion by dating human footprints preserved by volcanic ash in an abandoned quarry in Mexico.

They say the first Americans may have arrived by sea, rather than by foot.

The currently accepted theory is that the continent's early inhabitants arrived 12,500 years ago, by crossing a land bridge between Siberia and Alaska.

Details of the latest findings were unveiled at the UK Royal Society's Summer Science Exhibition.

Ancient lake

Scientist Silvia Gonzalez of Liverpool's John Moores University and her colleagues found the footprints in the quarry, some 130km (80 miles) south-east of Mexico, in 2003.

But they have only finished dating them this year.

"The footprints were preserved as trace fossils in volcanic ash along what was the shoreline of an ancient volcanic lake," Ms Gonzalez said.

She explained that curious early Americans would have most probably walked across the new shoreline as the volcano erupted.

Their footprints were soon covered in more ash and lake sediments and, when water levels rose, became as solid as concrete.

Ms Gonzalez says the tracks show that the first colonies may have arrived on water.

Click to expand...