WASHINGTON: 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.

A 2021 study by these researchers also dated the footprints, based on tiny plant seeds embedded in the sediment alongside them, to about 21,000 to 23,000 years ago. This was met with skepticism from some scientists who questioned the dating conclusion.

“Every dating technique has strengths and weaknesses, but when three different techniques all converge on the same age range, then the resulting ages are exceptionally robust,” said Jeff Pigati, a research geologist at the US Geological Survey (USGS) in Denver and co-lead author of the research published in the journal Science.

“Our original results were controversial, and we knew all along that we needed to independently evaluate the seed ages to develop community confidence in them. This paper is that corroborative exercise,” added study co-lead author Kathleen Springer, also a USGS research geologist in Denver.

Homo sapiens arose in Africa more than 300,000 years ago and later spread worldwide. Scientists believe our species entered North America from Asia by trekking across a land bridge that once connected Siberia to Alaska.

Published in Dawn, October 6th, 2023