For Native peoples on the Great Plains grasslands that stretch from the Rocky Mountains to the Missouri River, horses took on a central economic and military role, enabling bison hunting on a large scale and raiding across vast distances. “The introduction of this technology, of horses, changed Great Plains cultures,” says Carlton Shield Chief Gover, a member of the Pawnee Nation and an archaeologist at the Indiana University Museum of Archaeology and Anthropology. “It’s the equivalent of the airplane. It shrank the world.” Knowing when that happened is critical, he says. A new study today in Science, of which Shield Chief Gover is a co-author, offers a startling answer.
Centuries ago, the Americas were apparently horseless—even though Equus had evolved in the Americas more than 4 million years ago, spreading west from there into Eurasia and Africa. When the ancestors of Native Americans entered North America toward the end of the last ice age, more than 14,000 years ago, they would have encountered herds of wild horses. From the archaeological evidence—cutmarks on bones found at a handful of sites—it seems early Americans hunted horses and used their bones as tools, but did not domesticate or ride them. And by 5000 years ago at the latest, the fossil record suggests, North America’s horses were gone. Along with nearly 40 other species of megafauna, from saber-toothed tigers and mammoths to camels, they were wiped out by hunting, climate change, or both.
It wasn’t until 1519 C.E., when Spanish conquistador Hernán Cortés made landfall on the Gulf Coast of Mexico, that horses entered the Americas again. His 16 horses stunned local people, and the shock helped him defeat the Aztec Empire just 2 years later. In the centuries that followed, the horse spread once again across the continent, this time as a status symbol, means of transport, and hunting companion rather than prey. In the process, it set off massive human migrations, as some Native groups shifted to more mobile lifestyles. It also unleashed struggles over resources on the Plains and elsewhere.
Historians have tended to date the widespread adoption of the horse by Native peoples to the 18th century, when the first European travelers recorded its presence in the central and northern Plains. But in the sweeping new study, based on archaeological evidence, radiocarbon dating, isotope analysis, and ancient DNA, Shield Chief Gover and dozens of other researchers conclude that horses had made it that far north up to a century earlier. The study shows they had begun to spread within a few decades after the Spanish introduced them to the Southwest in the 16th century.