Spatially explicit analysis sheds new light on the Pleistocene megafaunal extinction in North America

Abstract

Abstract.-The late Pleistocene megafaunal extinctions may have been the first extinctions directly related to human activity, but in North America the close temporal proximity of human arrival and the Younger Dryas climate event has hindered efforts to identify the ultimate extinction cause. Previous work evaluating the roles of climate change and human activity in the North American megafaunal extinction has been stymied by a reliance on geographic binning, yielding contradictory results among researchers. We used a fine-scale geospatial approach in combination with 95 megafaunal last-appearance and 75 human first-appearance radiocarbon dates to evaluate the North American megafaunal extinction. We used kriging to create interpolated first-and last-appearance surfaces from calibrated radiocarbon dates in combination with their geographic autocorrelation. We found substantial evidence for overlap between megafaunal and human populations in many but not all areas, in some cases exceeding 3000 years of predicted overlap. We also found that overlap was highly regional: megafauna had last appearances in Alaska before humans first appeared, but did not have last appearances in the Great Lakes region until several thousand years after the first recorded human appearances. Overlap in the Great Lakes region exceeds uncertainty in radiocarbon measurements or methodological uncertainty and would be even greater with sampling-derived confidence intervals. The kriged maps of last megafaunal occurrence are consistent with climate as a primary driver in some areas, but we cannot eliminate human influence from all regions. The late Pleistocene megafaunal extinction was highly variable in timing and duration of human overlap across the continent, and future analyses should take these regional trends into account.

Population reconstructions for humans and megafauna suggest mixed causes for North American Pleistocene extinctions

“…For instance, using ancient DNA and radiocarbon records, Cooper et al 2 derive detailed time series for multiple megafauna genetic clades or species in both Eurasia and Eastern Beringia and show that the period encompassing the B-A and YD is characterized by a higher frequency of extirpations or global extinctions than any other over the last 25,000 years. Since it is known that many now-extinct genera of North American megafauna survived the B-A 1,12–14 , attention has focused on the potential role of conditions during the YD in driving extinctions in this region 5,12,15,16 .…”

An Assessment of Stone Weapon Tip Standardization During the Clovis–folsom Transition in the Western United States

“…A well-known transition occurred across the Great Plains, Southwest, and Rocky Mountain regions of North America beginning 12,700–12,600 cal BP (Meltzer 2009; Surovell, Boyd et al 2016), when the Clovis culture and its iconic fluted point was replaced by the Folsom culture and its likewise iconic point. Until 12,900–12,700 cal BP (Waters and Stafford 2007, 2014), western Clovis groups hunted a variety of prey, including, on occasion, now-extinct megafauna such as mammoth and large bison (DeAngelis and Lyman 2016; Emery-Wetherell et al 2017; Grayson and Meltzer 2015; Meltzer 2015; Surovell, Pelton et al 2016). This period encompassed a climate that changed from global warming at the end of the Pleistocene to global cooling during the first century of the Younger Dryas (Sellet 2018; Straus and Goebel 2011).…”

What does the occurrence of Sporormiella (Preussia) spores mean in Australian fossil sequences?

“…Conversely, Emery‐Wetherell et al . () find the data across North America inconclusive for identifying a single causal agent in the demise of the megafauna.…”

“…For example, Robinson et al (2005) investigated Sporormiella and fire histories as related to human activities and megafaunal decline, and concluded the extinctions were human-mediated. Conversely, Emery- Wetherell et al (2017) find the data across North America inconclusive for identifying a single causal agent in the demise of the megafauna.…”