Footprints at the base of trench in White Sands National Park. Credit: USGS
Original Dating Concerns
A crucial point of contention fixated the precision of the original ages, which were obtained by radiocarbon dating. The age of the White Sands footprints was initially identified by dating seeds of the common marine plant Ruppia cirrhosa that were found in the fossilized impressions. Nevertheless, water plants can obtain carbon from dissolved carbon atoms in the water rather than ambient air, which can potentially trigger the measured ages to be too old.
Re-Evaluation and Strengthening of Evidence
” Even as the initial work was being released, we were advancing to test our results with several lines of proof,” said Kathleen Springer, USGS research study geologist and co-lead author on the current Science paper. “We were confident in our initial ages, in addition to the strong geologic, hydrologic, and stratigraphic proof, but we understood that independent chronologic control was vital.”
Prints at base of trench, White Sands National Park. Credit: USG
For their follow-up study, the researchers focused on radiocarbon dating of conifer pollen, because it comes from terrestrial plants and for that reason prevents possible problems that occur when dating marine plants like Ruppia. In each case, the pollen age was statistically identical to the corresponding seed age.
” Pollen samples also helped us understand the more comprehensive environmental context at the time the footprints were made,” said David Wahl, USGS research geographer and a co-author on the current Science post. “The pollen in the samples originated from plants typically discovered in damp and cold glacial conditions, in stark contrast with pollen from the contemporary playa which shows the desert plants discovered there today.”
Additional Dating Methods Confirm Findings
In addition to the pollen samples, the group used a different type of dating called optically stimulated luminescence, which dates the last time quartz grains were exposed to sunlight. Using this approach, they found that quartz samples collected within the footprint-bearing layers had a minimum age of ~ 21,500 years, offering more support to the radiocarbon results.
With 3 different lines of proof pointing to the same approximate age, it is highly unlikely that they are all inaccurate or biased and, taken together, supply strong assistance for the 21,000 to 23,000-year age variety for the footprints.
Reference: “Independent age approximates deal with the debate of ancient human footprints at White Sands” by Jeffrey S. Pigati, Kathleen B. Springer, Jeffrey S. Honke, David Wahl, Marie R. Champagne, Susan R. H. Zimmerman, Harrison J. Gray, Vincent L. Santucci, Daniel Odess, David Bustos and Matthew R. Bennett, 5 October 2023, Science.DOI: 10.1126/ science.adh5007.
The research study group consisted of scientists from the USGS, Lawrence Livermore National Laboratory, the National Park Service, and academic organizations. Their continued research studies at White Sands concentrate on the environmental conditions that allowed individuals to thrive in southern New Mexico during the Last Glacial Maximum and are supported by the Climate Research and Development Program|U.S. Geological Survey and USGS-NPS Natural Resources Protection Program.
Fossilized footprints in White Sands National Park sparked a scientific debate. Subsequent research, utilizing different dating techniques, consistently supports the footprints being 21,000 to 23,000 years of ages. Credit: USGS, NPS, Bournemouth University
Two new lines of proof support the 21,000 to 23,000-year age estimate of the footprints initially explained and dated in 2021.
In 2021, scientific dating results from footprints discovered at White Sands National Park in New Mexico began a worldwide discussion that triggered public creativity and prompted dissenting commentary throughout the clinical neighborhood regarding the accuracy of the ages.
” The immediate reaction in some circles of the archeological community was that the accuracy of our dating was inadequate to make the remarkable claim that people were present in North America throughout the Last Glacial Maximum. But our targeted approach in this existing research study really settled,” stated Jeff Pigati, USGS research geologist and co-lead author of a newly published study that validates the age of the White Sands footprints.
By U.S. Geological Study
October 6, 2023
Subsequent research, utilizing various dating approaches, consistently supports the footprints being 21,000 to 23,000 years old. A crucial point of contention centered on the accuracy of the original ages, which were gotten by radiocarbon dating. The age of the White Sands footprints was initially figured out by dating seeds of the common water plant Ruppia cirrhosa that were discovered in the fossilized impressions. For their follow-up study, the researchers focused on radiocarbon dating of conifer pollen, since it comes from terrestrial plants and therefore prevents possible problems that develop when dating water plants like Ruppia. In each case, the pollen age was statistically similar to the corresponding seed age.