SYDNEY - British scientists believe that they have unearthed human footprints in central Mexico that are approximately 40,000 years old. The discovery is set to challenge previous studies that put the arrival of the first humans in the Americas close to 13,500 years ago.
The discovery was made in 2003 by Professor Mathew Bennet, from Bournemouth University and Dr. Silvia Gonzalez, from Liverpool John Moores University. The footprints were found in an abandoned quarry close to Cerro Toluquilla volcano in the Valsequillo Basin, located near Puebla, south of Mexico City.
According to Dr. Gonzalez, the footprints were preserved as fossils in volcanic ash along with what was the shoreline of an ancient volcanic lake.
Dr. Gonzalez believes that Climate variations and the eruption of the Cerro Toluquilla volcano caused the volcanic lake levels to rise and fall, exposing the Xalnene volcanic ash layer. Dr. Gonzalez said the footprints were preserved when water levels rose making them as hard as concrete. The footprints had been uncovered after quarry workers removed approximately three yards of lake sediment that had been deposited on top of the volcanic ash layer where the footprints were located.
Using laser technology, an international team of scientists analyzed the footprints and dated them at around 40,000 years ago. These findings pose a challenge to previously held ideas about the settlement of the Americas.
Previously it has been accepted by the scientific community that the first humans arrived in North America after the last ice age about 13,500 years ago.
It was believed that humans crossed a previously existing land bridge from Asia into what is now Alaska and eventually populated the entire continent.
This theory has been supported by the discovery of stone tools called Clovis. These tools have been left behind and have been dated as being from around 13,500 years ago.
Professor David Huddart, of Moores University, and a collaborator on the discovery said: “The existence of 40,000-year-old human footprints in Mexico means that the ‘Clovis First’ model of human occupation can no longer be accepted as the first evidence of human presence in the Americas.”
Dr. Gonzalez said the findings supported a theory that the first colonies may have arrived by water, using the Pacific coast migration route, rather than on foot and that different groups of humans may have migrated into the Americas at different times.