First Americans hunted largest game through Western Hemisphere

First Americans hunted largest game through Western Hemisphere

New research led by a University of Alaska Fairbanks archaeologist reveals that the earliest Native Americans had highly specialized diets, primarily hunting the largest animals on the landscape, and they targeted these megafauna consistently from Alaska to South America.

The study, published today in the journal Science Advances, examined data from 50 archaeological sites excavated throughout the Americas. An international team of researchers from the U.S., Canada and Argentina analyzed animal bones at campsites and identified species, grouped by how much food they provided. UAF anthropology professor Ben Potter and McMaster University researcher James Chatters led the study.

What they discovered addresses one of archaeology's most contested questions: How did humans spread so rapidly across two continents?

"One of two competing ideas is dietary generalization: exploiting a wide variety of resources that would differ based on region," said Potter. "The other is megafaunal specialization: focusing on just a few large-bodied prey."

The study focused on three of the earliest and most widespread cultural groups in the Americas: Eastern Beringians in Alaska and the Yukon, Clovis people across North America and Fishtail Projectile Point people in South America. Within those groups, the researchers concluded that 83% to 88% of their food came from massive plant-eaters such as mammoths, elephant-like gomphotheres and giant ground sloths, collectively known as megaherbivores.

In order to reach that conclusion, scientists looked at a variety of data. Bones from prey animals at each of the excavation sites showed what people were eating. They then calculated which and how many animals - large and small - could be expected to live in the nearby landscape. To account for body size, the team multiplied individual animal counts by each species' estimated edible biomass. Even when the researchers artificially inflated small-animal counts in their models as a test, megaherbivores still accounted for the overwhelming majority of available food.

"The test of dietary specialization isn't just how many of a given animal you find at an ancient campsite," Potter said. "It's what the record looks like relative to natural abundance. If early people were dietary generalists, you'd expect to find the most common animals would be more common in peoples' campsites."

Instead, they found the opposite.

"Animals like mammoths and ground sloths, which were actually quite rare in the landscape, completely dominate the archaeological record," he said. "Rabbits and mice, which would have been everywhere, barely register."

Potter said the focus on large herbivores for food also explains why the early toolkits appear very similar from California to Maine to Florida, and at sites in South America. People hunting the same kind of animal across radically different landscapes had no need to adapt their technology to local conditions. The tools found at the archaeological sites included implements for hunting large game, such as large fluted projectile points and specialized butchering implements. Fishing gear and plant-processing tools were notably absent.

This focus on hunting large prey also explains the rapid expansion of humans from Alaska through South America, the study finds.

When hunter-gatherers move into unfamiliar territory, they typically need generations to learn the new landscape, how to effectively hunt local small and medium-sized game, and which local plants are edible.

Building a diet around large mammals changes that dynamic.

"Mammoths, for example, can cover a tremendous range and occupy vast territories," said study co-author Mat Wooller, a professor at UAF. "In effect, specialist hunter-gatherers used their knowledge of megaherbivores, like mammoths, to expand successfully across the continents rather than learning about each localized ecosystem they encountered."

The study also found that the timing of megafauna extinctions tracks with human arrival, not all at once, but like a wave moving southward down the continents.

In Alaska, mammoths and horses disappeared around 13,300 years ago, at the end of the earliest known human occupation there. Clovis-era megafauna in North America were gone by 12,800 years ago,and gomphotheres and giant ground sloths survived in South America until about 11,600 years ago.

Potter said the same sequence of arrival, overlap and extinction played out again and again, each time a little further south, making a strong circumstantial case for human hunting as a major contributing factor to megafauna extinction, compounded by climate change, which could have reduced their habitat, making them more susceptible to hunting pressure.

"Megaherbivores reproduce slowly, space births widely and, as adults, have no natural predators," he said. "They would have had no learned wariness of new, technologically sophisticated human hunter-gatherer populations."

Members of the research team include Potter, Chatters and Wooller; Luciano Prates of Universidad Nacional de la Plata, Argentina; S. Ivan Perez of Museo Histórico y Arqueológico, CONICET, Argentina; Todd Surovell and Robert Kelly of the University of Wyoming; and Gustavo Politis of Universidad Nacional del Centro de la Provincia de Buenos Aires, Argentina.

ADDITIONAL CONTACTS: Ben Potter, [email protected], 907-474-7567; Mat Wooller, [email protected], 907-474-6738

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