Humans walked America 40,000 years ago

William Atkins
Wednesday, 16 July 2008 19:27

Science - Biology

An international team of geoarchaeologists have discovered footprints in central Mexico that place the presence of early humans in the Americas further back than previous thought: around 40,000 years ago. The discovery helps to settle a long-standing debate as to when humans first came to the Western Hemisphere.


British geoarachaeologist Silvia Gonzalez (Liverpool John Moores University (LJMU), in the United Kingdom) lead a team of geoarchaeologists in making this very important discovery on the first presence of humans within the Americas.

The footprints found in rocks (which were once, long time ago, volcanic ash) helps to confirm that humans were in the Valsequillo Basin of central Mexico around 40,000 years ago.

The Gonzalez team is part of the research program called Environmental Factors in the Chronology of Human Evolution and Dispersal (EFCHED), which is part of the Natural Environment Research Council.

The researchers mapped and scanned the footprints using three-dimensional (3D) laser technology. The scans were later reproduced at sub-millimeter precision at the University of Bournemouth using rapid-proto-typing technology.

Specifically, Gonzalez, David Huddart (also with LJMU), and Matthew Bennett (Bournemouth University) found 269 footprints--both from animals and humans--in an abandoned quarry close to the Cerro Toluquilla volcano, located in the Valsequilio Basin, near the city of Puebla, about 80 miles (130 kilometers) southeast of Mexico City.

According to the Liverpool John Moores University article “The Oldest American: Footprints from the Past: Will a footprint rewrite the history books?”, Gonzalez stated, "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 Xalnene volcanic ash layer."

The discovery is important to finding out the first presence of early humans in the Americas because a fierce debate has raged as to when such humans first set foot in the Western Hemisphere. Previous estimates placed humans in the Western Hemisphere around 20,000 years ago.

Based partially on this discovery, Gonzalez states, “We think there were several migration waves into the Americas at different time by different human groups.” [LJMU]

David Huddart, a member of the team making this exciting discovery, provides further comments on page two about the debate on early human presence in the Americas.