Scientists have revealed the secret of the legend about the island, where feral horses themselves sailed

The unexpected discovery of a 16th-century horse tooth in what is now Haiti provided credibility to an old folk story about the origin of wild horses on an island off Maryland and Virginia.

The famous Chincoteague wild ponies have lived for centuries on Assateague Island, a barrier island on the Atlantic coast. But no one knows exactly how they got there. A 1947 children’s book inspired by local legend, The Chincoteague Misty, suggests that the ponies are the descendants of Spanish horses that swam to the island after a Spanish ship was wrecked off the coast of Virginia and became feral over the years.

But the study, published in PLoS ONE by scientists at the Florida Museum of Natural History on July 22, provides new scientific support for a theory based on the discovery of the oldest known domesticated horse DNA in America.

Nicolas Delsol, a researcher at the Florida Museum of Natural History, examined cow bones from 16th-century archaeological sites to understand how domesticated cows arrived in the Americas during Spanish colonization. He sequenced the DNA of “a huge collection of archaeological sites” from Puerto Real, an ancient Spanish city located in what is now Haiti. The city was founded by the Spaniards in 1507 but abandoned in 1578.

“One of the bones that I thought was from a cow was misidentified,” Delsol explained in an interview with CNN. “The small fragment of the tooth was actually from a horse.”

The discovery was “completely unexpected,” Delsol said. “We quickly realized that this might be the first domestic horse genome that we received from the early colonies of the Americas.”

The genetic analysis “confirms what we might expect from historical documents, saying that the first horses were brought on board in boats from the Iberian Peninsula from southern Spain, most likely,” Delsol said. Horses were an important part of Spanish society, he says, so important that the Spanish colonizers took them with them on the grueling and logistically difficult journey across the Atlantic.

But genetic analysis of a 16th-century tooth also helped Delsol to identify the closest living relative of the first domestic horses: the Chincoteague pony. The genetic similarity supports the notion that ponies are descendants of early Spanish horses, Delsol says.