3 new studies support human overhunting as the cause of Late Pleistocene extinctions in South America, and perhaps the most interesting study is an isotopic analysis of the Anzick child’s remains. The Anzick child was an 18-month-old toddler deliberately buried after his death. The body was discovered in Wilsall, Montana during 1968 and was associated with over 100 Clovis artifacts. Radiocarbon dates suggest the toddler lived sometime between 12,900 years BP-12,695 years BP. In 2014 local Indian fanatics insisted scientists let them rebury the body because of their stupid religious beliefs, but genetic evidence suggests this tribe was not even directly descended from the baby’s parents. Instead, the baby was more closely related to Indians living in Central and South America today. Nevertheless, scientists still had isotopic data from the child’s bone chemical composition, and they were able to determine the baby’s mother’s diet. (The child likely still got most of his nutrition from nursing.)
Scientists used a statistical model of the isotopic composition to determine mammoth made up 35%-40% of the mother’s diet, showing that megafauna was the most important resource for the Clovis people in this region. Elk made up 15%-17% of their diet, camel and/or bison made up 21% of their diet, horse made up 6% of their diet, and small mammals only 4% of their diet. (Bison and camel had a similar diet, so scientists can’t distinguish their isotopic signatures.) The ancestors of the Clovis may have been generalist foragers who had already reduced populations of horses and camels, but they became big game hunting specialists during the Clovis era. This study also compared the Anzick child’s isotopic composition with those from other large carnivores that lived in the region then. The Clovis diet was most similar to that of the scimitar-toothed cat. This big, fanged cat is thought to have specialized in hunting juvenile mammoths. Archaeologists and anthropologists who proclaimed humans hardly ever hunted mammoth were certainly wrong. Large mammals were the central item in the diet of the Clovis culture, and humans surely overexploited them into oblivion.
Pie charts from the below referenced study (Chatters et. al.) showing the percentage of mammals that made up each species diet. Humans enjoyed a diet most similar to Homotherium–the scimitar-toothed cat. FYI, Arcotodus = short-faced bear, Aenocyon = dire wolf, Miracinonyx = psuedo cheetah, Canis = timber wolf, Panthera = giant lion, Bootherium = helmeted musk-ox, Cervus = elk, Equini = horse, Mammuthus = mammoth, Camelops = camel, Bison = bison, Ovis = big horn sheep, Rangifer = caribou, Antilocapra = pronghorn.
Another study examined the database of 1600 reliable radio-carbon dates of human-occupied sites in South America during the Late Pleistocene. The scientists used 6 different statistical models to estimate the earliest human arrival in South America, and the how rapidly humans colonized the continent. They estimated humans arrived in South America between 16,600 years BP-15,100 years ago, but they lean toward the more recent date. The initial colonizers lived in low population densities and are less visible in the archaeological record. The scientists didn’t use dates earlier than this because the evidence is inconclusive. Both human and megafauna populations increased following the Last Glacial Maximum, but eventually the latter became extinct as humans became more common in the environment. The extinctions seem to correspond to human population densities and not climate change. Grassland environments favorable to megafauna retracted during a Late Pleistocene climate fluctuation, but megafauna began declining 500-1400 years before this, and there was still plenty of grassland habitat available.
A third study, authored by several of the scientists who wrote the study discussed above, compared megafauna populations both spatially and temporarily with the prevalence of fishtail projectile points. Fishtail projectile points were the most common arrowhead used by South American Indians to hunt large mammals. Megafauna populations began to increase about 17,500 years ago when climate following the Last Glacial Maximum improved. (Megafauna population densities were estimated using radio-carbon dates of subfossil remains in the paleobiology database. In my opinion this is a little dubious because the fossil record might not represent actual population densities.) About 13,500 years ago when Indians started using Fishtail projectile points, megafauna populations began to decline. Patagonian grassland and the Pampas hosted the highest populations of megafauna, while the Andes hosted the lowest. Species of megafauna covered in this study included Hippidion (a genus of horses restricted to South America during the Late Pleistocene), horses belonging to the Equus genus, llama, 3 species of ground sloth, glyptodont, notiomastodon, and gompothere. The last 2 were elephant-like species. South America suffered an even larger percentage of large mammal extinctions than North America during the end of the Pleistocene. 82% of South America’s large mammals became extinct compared to 70% of North America’s large mammal extinctions. The authors of this study feel confident humans were primarily responsible because megafauna began declining centuries before any major climate fluctuation, but they did decline when Fishtail point projectiles became more prevalent in the archaeological record.
Fishtail projectile points were used by Paleoindians to kill large mammals. An increase of their appearance in the archaeological record is associated with a decline in megafauna populations.
Chart showing the correlation between the prevalence of Fishtail projectile points and a decline in megafauna populations. From the below referenced study by Prates (2021).
References:
Chatters, J.; B. Pottter, S. Fiedel, J. Morrow
“Mammoth Featured Heavily in Western Clovis Diet”
Science Advances 10 (49) December 2024
www.science.org/doi/10.1126/sciadv.adr3814dr3814
Prates, L.; G. Politis, S. Perez
“Rapid Radiation of Humans in South America after the Last Glacial Maximum: A Radiocarbon-based Study”
PLOS ONE July 2020
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0236023
Prates, L.; S. Perez
“Late Pleistocene South American Megafauna Extinctions Associated with Rise of Fishtail Points and Human Populations”
Nature Communications 12 (2175) 2021
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