Humans trod the landscape of North America thousands of years earlier than previously thought, according to new research that confirms the antiquity of fossilised footprints at White Sands National Park in New Mexico using two further dating approaches.
The footprints date to about 21,000 to 23,000 years ago, based on radiocarbon and optically stimulated luminescence dating techniques, researchers said on Thursday, showing that our species Homo sapiens already had a foothold in North America during the most-inhospitable conditions of the last Ice Age.
Massive ice sheets covered wide swathes of the continent - reaching as far south as Illinois - amid extensive glaciation.
