Perspectives on a Post-White Sands Coast: Re-Evaluating Research into Early Peopling of the Northwest Coast of North America

ABSTRACT

In light of new dates associated with the White Sands human footprints in New Mexico that suggest humans were in North America south of continental ice sheets during (or before) the Last Glacial Maximum (LGM), I discuss the implications for the late Pleistocene archaeology of the Northwest Coast – the presumed “Pacific Coastal Route” for entry into the continent. I argue that we can and should employ state-of-the-art methods to push our paleoenvironmental reconstructions back through the LGM to enable a search for evidence of people entering North America via this route. However, I more strongly emphasize that documenting the earliest postglacial occupations of the Northwest Coast remains a significant endeavor, both from a disciplinary perspective, but also for the Indigenous descendent communities inhabiting the region. Rather than rendering our archaeological efforts on the Northwest Coast wasted, White Sands opens new and exciting research questions, with implications reaching throughout the Americas.

KEYWORDS:

• Peopling of the Americas
• Northwest Coast
• White Sands
• Pacific Coastal Route
• paleoenvironmental reconstruction

Acknowledgements

This short essay was inspired by several invigorating conversations with Duncan McLaren, Daryl Fedje, Angela Dyck, and Chris Hebda – a team of colleagues with whom I have had the pleasure of puzzling over what the heck was going on during the late Pleistocene along the Northwest Coast for the last few years. Not all these individuals are quite as accepting of the new White Sands results as I am, but we collectively agree that these are exciting discussions to have. This essay was also immensely improved by editorial comments from Ian Sellers, Haeden Stewart, and Duncan McLaren. I would also like to extend my gratitude to four anonymous reviewers for reading and commenting on this piece, and to Ted Goebel for editorial assistance.

Disclosure statement

No potential conflict of interest was reported by the author.

Notes

1 Indicative of the pace at which this exciting research is moving, between submission of this essay and publication, Rachal, Dello-Russo, and Cuba (2024) have published a new critique of Bennett et al.’s (2021) and Pigati et al.’s (2023) footprint ages. While primarily focused on (convincingly) demonstrating that the radiocarbon dates on Ruppia seeds are most likely impacted by the hard water reservoir effect (essentially buttressing the findings of Oviatt et al. 2023), they also suggest (in a postscript) that the newly published pollen ages are unreliable because they may have been old pollen grains washed into place thousands of years after initial deposition. I offer two brief considerations. First, even accepting that the ages on the Ruppia seeds were impacted by a hard water effect, of the 11 modern-aged specimens dated by Rachal, Dello-Russo, and Cuba (2024), 10 yielded age offsets between ∼1700 and ∼3800 years (and the mean of those was 2700 years). If the ages of the Ruppia associated with the human footprints were affected by offsets of that magnitude, they would still fall within or shortly after the time of the LGM, and would still be significantly older than any other widely accepted archaeological site in the Americas. Second, if the terrestrial plant pollen grains dated by Pigati et al. (2023) were old pollen re-deposited later and then walked over by people, it seems a highly remarkable coincidence that the time between the initial deposition and re-deposition of those grains would be identical to the age-offset of the Ruppia seeds caused by the hard water effect. I personally find it more likely that the pollen and the Ruppia are generally contemporaneous with each other, and that they shortly pre-date the footprints. It is likely that Bennett et al.’s (2021) Ruppia ages are impacted by a hard water effect that makes them more recent than their published calibrated values, but that the actual ages still fall within the much broader calibrated age ranges of the pollen (i.e., the pollen dates are associated with ±2500 year error ranges). Ultimately, however, I agree with Rachal et al. (2022, 931) (and probably most others observing this debate!) that an in situ macrofossil with a terrestrial carbon source and in clear association with the footprints needs to be found and dated to resolve the aging issue. Regardless, the suggestions made in this essay are still relevant.

Additional information

Notes on contributors

Bryn Letham

Bryn Letham earned his PhD at the University of British Columbia in 2017. His research interests include using coastal geoarchaeology and paleoenvironmental reconstruction to interpret transforming landscapes in western North America from the late Pleistocene to the present day.