When did the first human being land in the Americas? For a long time, conventional wisdom suggested that the first humans entered North America through a land bridge between Siberia and Alaska (over the current Bering Strait) about 12-15,000 years ago during the last Ice Age, when the sea levels dropped. But there are competing theories, which suggest that humans entered the Americas by boat across the Pacific, or by walking along the Greenland coast.

Left: Closeup, Right: Walk in the park! (Courtesy: Nature)Now a new evidence might push the date of this first arrival, further back in time. Researchers think they may have found footprints in southern Mexico that mark the oldest evidence for the presence of humans in the Americas. The impressions are preserved in volcanic ash outside the city of Puebla, and have been dated at 40,000 years ago!! This, if conclusively proved, would lend credence to the theory that humans crossed into the New World much earlier than previously thought.
Though they do look like footprints, researchers need to make sure that they are not some quirky creations of Mother Nature. But it does look like the area is peppered with more than 200 impressions that seem to be footprints from several people, including children, along with birds, cats, dogs and species with cloven feet:):). According to geoarchaeologist Silvia Gonzalez of Liverpool John Moores University, UK, these people might have been fleeing an eruption from the nearby Cerro Toluquilla volcano. It is the same volcanic ash that also helped preserve the prints for the last thousands of years, along with biological material such as shells which were used to date the ash strata:):).