Horses are not native to South America today, though their history on the continent spans millions of years. While modern horses found across South America are descendants of those brought by Europeans, the ancestors of all horses actually originated in the Americas. Their journey involves deep geological time and ecological shifts. This clarifies why present-day horses are a reintroduced species rather than a continuous native lineage.
The Deep History of Horses
The genus Equus (modern horses, asses, and zebras) originated in North America approximately 4 million years ago. From North America, these ancient equids migrated. They spread into Asia and Europe across the Bering land bridge during lower sea levels. These early horses also dispersed southward into South America via the Isthmus of Panama around 2.6 million years ago, establishing diverse populations.
These horses thrived across these landmasses for millions of years. Fossil records document the development of equids in North America, with early species evolving into the single-toed forms seen today. The Americas were once home to a variety of horse species before their disappearance.
Disappearance from the Americas
An extinction event occurred at the end of the last Ice Age, roughly 10,000 to 8,000 years ago. During this period, all native horse species across both North and South America vanished. This widespread disappearance was part of a larger megafaunal extinction that affected many large mammals on the continents.
The reasons for this extinction are debated, with leading theories pointing to a combination of factors. Climate change played a role, as the transition from the Pleistocene epoch brought alterations to landscapes and vegetation. Additionally, the arrival of early human populations in the Americas and their hunting practices are considered contributing factors.
Return to the Continent
Modern horses, Equus caballus, returned to the Americas in the late 15th and early 16th centuries with European colonizers, predominantly the Spanish. Christopher Columbus brought the first Iberian horses to the Caribbean in 1493, with Hernán Cortés introducing them to the continental mainland in 1519. These reintroduced horses rapidly adapted and thrived across the continent, including South America.
From early imports to Mexico, horses spread quickly through the Americas. Escaped or pilfered horses formed large herds of feral animals, such as mustangs, and proliferated across plains. The Spanish also brought horses directly to various South American regions, including Panama, Brazil, Peru, and Argentina, starting around 1531. This reintroduction led to the establishment of feral and domesticated horse populations seen in South America today.
The reintroduction of horses influenced indigenous cultures and the landscape across the Americas. Native peoples quickly integrated horses into their societies, revolutionizing transportation, hunting practices, and warfare. Horses became central to many indigenous ways of life, leading to social and economic transformations. The presence of horses reshaped the continent’s ecosystems and human societies, marking a new chapter in their long history in the Americas.