Newly Discovered Fossil Footprints Carry Implications for Cause of Megafaunal Extinctions

By Claire Brandes

Within North American archeology, conventional wisdom has it that the Clovis people represent the continent’s earliest occupation around 12,000 years ago, after the ice sheets of the Last-Glacial Maximum, which would have made it impossible to travel via Beringia, receded. These early hunter-gatherers have long been blamed for the downfall of many megafaunal species, including the wooly mammoth. Not only are they known for their distinctive spear points thought to have been used to hunt large game, the extinction event during which 35 genera of North American megafauna met their demise occurred roughly in tandem with the arrival of the Clovis people. However, new research suggests that this damning evidence may turn out to be merely circumstantial, after all. 

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Fossilized human footprints discovered in White Sands National Park, New Mexico have provided new evidence surrounding the peopling of the Americas that may exonerate the Clovis people. Researchers involved analyzing the footprints applied radio-carbon dating to seeds found in sediments surrounding the footprints as well as the layers above, and below. Their results, published in one of the most prestigious academic journals, Science, date the footprints to 23,000 years ago, pushing humans’ arrival in the Americas back by millennia.   

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Even more interesting are the mammoth tracks found in the stratigraphic layers meters above the footprints’ location. As it turns out, early Americans coexisted with megafaunal species for much longer than previously thought. Dr. Sally Reynolds, paleontologist at Bournemouth University and co-author of the publication, commented, “It may well be that the humans were harvesting these megafauna as part of their killing and their hunting more sustainably in the earlier years, and potentially through time, as the populations grew, the balance of power shifted and the humans started perhaps overharvesting these megafauna.” 

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In accordance with this theory, several scholars have produced studies that suggest early humans were incapable of causing the complete collapse of the megafauna all on their own. Researchers with the University of Utah Department of Anthropology, David Byers and Andrew Ugan concluded that based on the caloric value of a mammoth, early hunters would have expended more energy than gained by exploiting these animals as a food source, thus discounting the plausibility of large-game specialization in the Pleistocene. Nonetheless, researchers have found definitive proof that early humans must have at least occasionally hunted megafauna based on archaeological kill sites attributed to the Clovis people. 

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In summary: while early humans certainly hunted megafauna, it is unlikely that they relied on these species to sustain them. Furthermore, fossilized footprints suggest that people arrived in the Americas long before megafaunal extinctions began to occur. Where does this leave us? In line with Dr. Sally Reynold’s thoughts about the matter it seems most likely that, while humans were able to hunt megafauna sustainably, something happened that caused overharvesting to occur. One possible cause is the climate change that occurred during the Pleistocene epoch. Complicating this debate, it remains unclear when continuous occupation of North America truly occurred. Are these fossil footprints indicative of a large human population in the area? 

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Despite the uncertainties that remain, this discovery provides an amazing look into the past, and is celebrated by paleoanthropologists as we continue to uncover details about human origins.

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Author: Claire Brandes is a 4th year anthropology major at the University of Georgia with interests in paleoanthropology and paleoecology. She intends to enroll in an anthropology PhD program for the Fall of 2022. 

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References:

Bennett et al. (2021). Evidence of humans in North America during the Last Glacial Maximum. Science, 373, 1528-1531. 

Bulte, E., Horan, R. D., & Shogren, J. F. (2005). Megafauna extinction: A paleoeconomic theory of human overkill in the Pleistocene. Journal of Economic Behavior & Organization, 59(3), 297-323.

Byers, D. A., & Ugan, A. (2005). Should we expect large game specialization in the late

Pleistocene? An optimal foraging perspective on early Paleoindian prey choice. Journal of Archaeological Science, 32(11), 1624-1640.

Gershon, L. (2021, September 24). Prehistoric footprints push back timeline of humans’ arrival in North America. Smithsonian Magazine.