British scientists today claimed they have unearthed 40,000 year-old human footprints in central Mexico which shatter previous theories on how humans first colonised the Americas.
Dr Silvia Gonzalez, from Liverpool John Moores University (LJMU), who led the team of researchers, said the findings were “the tip of the iceberg” and would help rewrite the history books.
She said the discovery, near to the city of Puebla, 130 km southeast of Mexico City, challenges the traditionally held view that settlers first crossed the Bering Straits, from Russia to Alaska, at the end of the last ice age around 11,500 to 11,000 years ago.
Evidence for this theory comes from “Clovis Points” tools used to hunt mammoths found in many locations in the American continent.
But the discovery of footprints in the Valsequillo Basin, in September 2003, provides new evidence that humans settled in the Americas as early as 40,000 years ago, Dr Gonzalez said.
She said: “We think there were several migration waves into the Americas at different times by different human groups.”
The footprints were found in an abandoned quarry close to the Cerro Toluquilla volcano by Dr Gonzalez, Professor David Huddart (LJMU) and Professor Matthew Bennett, of Bournemouth University, and were subsequently studied and dated by a multinational team of scientists.
Dr Gonzalez said: “The footprints were preserved as trace fossils in volcanic ash along what was the shoreline of an ancient volcanic lake.
“Climate variations and the eruption of the Cerro Toluquilla volcano caused lake levels to rise and fall, exposing the volcanic ash layer.”
The geoarchaeologist said the early Americans would have been curious about the volcano erupting and walked across this new shoreline, leaving behind footprints that soon became covered in more ash and lake sediments.
The trails became submerged when the water levels rose again, so preserving the footprints.
Now as hard as concrete, theash is used locally as a building material.
The team was able to see the footprints without carrying out any excaation as quarry workers had already removed between two and three metres of lake sediments that had been deposited on top of the volcanic ash.
Professor Huddart said: “New routes of migration that explain the existence of these much earlier sites now need urgent consideration.
“Our findings support the theory that these first colonists may perhaps have arrived by water rather than on foot using the Pacific coast migration route.”
Ancient human and animal prints are a rarity due to the special conditions required for their preservation.
The discovery of the Valsequillo Basin footprints is an important addition to the global archive of human prints.
Models of the footprints can be seen at the Royal Society’s Summer Exhibition, at Carlton House Terrace, London.