Evolution of the horse

Horses evolved from fox-size to the horses we know today because they adapted to every environment across the Americas.  Survival meant horses’ soft-toed feet and small eyes turned into hard hooves and the largest eyes of any land mammal. Those eyes, located on the sides of their heads, meant they could eat and spot danger at the same time. The length of their legs and coats adapted to where they lived. Some became short and shaggy. Others lean and long. Their palates appreciated forage spread across their vast homelands from the Arctic to the tip of South America.

the horse and the ice age

America’s wild horses and millions of other large animals suffered a die-off at the end of the Third Ice Age. Climate change made food scarce. Weakening horses travelled long distances and battled other herbivores for each mouthful. Some hardy bands of horses headed north to survive the third Ice Age in Asia. Others stayed in North America and died there. As plants vanished, famine claimed the plant-eaters. Without them, meat-eaters starved, too.  

Did America’s wild horses go extinct?

Maybe. Modern science has made us rethink what we “know.” Carbon dating and DNA testing of fossils prove the Americas were not empty of horses for millions of years, as we once thought. Horses were gone for – at most -- eight thousand years. As research and exploration continue, we may discover remains of horses whose lives bridged the missing years between ancient equines and horses re-introduced by Spanish explorers and colonists in the 1490’s.

Beth Shapiro, an evolutionary molecular biologist from University of California, Santa Cruz, breaks down the history and science behind the native wild horse.