Americas oldest horse DNA supports folk origin – News


An abandoned Caribbean settlement discovered centuries after being forgotten and a case of mistaken identity in the archaeological record have conspired to rewrite the history of a barrier island off the coasts of Virginia and Maryland.

These seemingly unrelated threads were woven together when Nicolas Delsol, a postdoctoral researcher at the Florida Museum of Natural History, set out to analyze ancient DNA recovered from cow bones found in archaeological sites. Delsol wanted to understand how cattle were domesticated in the Americas, and genetic information stored in centuries-old teeth held the answer. But they also have a surprise in store.

“It was a chance finding,” he said. “I was sequencing mitochondrial DNA from fossil cow teeth for my Ph.D. and realized something was very different with one of the specimens when I analyzed the sequences.

Indeed, the specimen in question, a fragment of an adult molar, was not a cow’s tooth at all, but once belonged to a horse. According to a study published this Wednesday in the journal PLOS ONE, the DNA obtained from the tooth is also the oldest ever sequenced for a domestic horse in the Americas.

An unexpected opportunity

The tooth was extracted from one of the first colonized colonies in Spain. Located on the island of Hispaniola, the city of Puerto Real was founded in 1507 and for decades served as the last port of call for ships coming from the Caribbean. But rampant piracy and the rise of illegal trade in the 16th century forced the Spaniards to consolidate their power elsewhere on the island, and in 1578 the inhabitants were ordered to evacuate Puerto Real. The abandoned city was destroyed the following year by the Spanish authorities.

The remains of the once bustling harbor were inadvertently rediscovered by a medical missionary named William Hodges in 1975. Archaeological excavations of the site led by the Florida Museum’s distinguished research curator, Kathleen Deagan, were conducted between 1979 and 1990.

Horse fossils and related artifacts are incredibly rare in Puerto Real and similar sites from the era, but cow remains are a common find. According to Delsol, this skewed ratio is mainly due to the way the Spanish colonialists valued their cattle.

“Horses were reserved for high-ranking people, and owning one was a sign of prestige,” he said. “There are full-page descriptions of horses in the documents that record the arrival of [Hernán] Cortés in Mexico, showing how important they were to the Spaniards.

In contrast, cows were used as a source of meat and leather, and their bones were regularly dumped in communal waste piles called dumps. But a community’s trash is an archaeologist’s treasure, because trash from dumps often provides the clearest insight into what people ate and how they lived.

The specimen’s biggest surprise only came to light when Delsol compared its DNA with that of modern horses from around the world. Since the Spaniards brought their horses from the Iberian Peninsula to southern Europe, he expected that the horses still living in that region would be the closest living relatives of the 500-year-old specimen from Puerto Real. year.

Instead, Delsol found his loved ones more than 1,000 miles north of Hispaniola, on Assateague Island off the coasts of Maryland and Virginia. Wild horses have roamed the long stretch of the barrier island freely for hundreds of years, but exactly how they got there remains a mystery.

Folklore meets science

According to the National Park Service, which manages the northern half of Assateague, the most likely explanation is that the horses were brought in the 1600s by English settlers from the mainland in an effort to evade cattle taxes and fence laws. Others believe the feral herds are descended from horses that survived the sinking of a Spanish galleon and swam to shore, a theory popularized in the 1947 children’s novel “Misty of Chincoteague.” The book was later adapted for film, helping to spread the legend of the sinking to an even wider audience.

So far, there has been little evidence to support either theory. Proponents of the shipwreck theory claim that English settlers would be unlikely to lose track of their valuable livestock, while those in favor of an English origin of the herds point to the lack of nearby sunken ships and the omission of wild horses in the historical archives of the Region.

The DNA analysis results, however, unequivocally indicate that Spanish explorers are the most likely source of the horses on Assateague, Delsol explained.

“It’s not widely reported in historical literature, but the Spanish were exploring this region of the mid-Atlantic quite early in the 16th century. Early colonial literature is often uneven and not completely thorough. Just because they don’t mention the horses doesn’t mean they weren’t there.

Assateague’s wild herds weren’t the only horses to return to their wild heritage after arriving in the Americas. Settlers from all over Europe brought with them horses of varying breeds and pedigrees, some of which resisted their bonds and fled into the surrounding countryside.

Today, the United States Bureau of Land Management estimates that there are approximately 86,000 feral horses across the country, most of which are located in western states, such as Nevada and Utah. Delsol hopes that future studies of ancient DNA will help decode the complex history of equine introductions and migrations that have occurred over the past few centuries and provide a clearer understanding of the current diversity of wild and domestic horses.

The study was published in the journal PLOS ONE.

Jessica Oswald of the University of Nevada, Reno; Elizabeth Reitz of the Georgia Museum of Natural History; and Brian Stucky, Kitty Emery and Robert Guralnick of the Florida Museum of Natural History are also authors of the study.

Funding for the study was provided in part by the National Science Foundation (DDIG 1930628) and the Fulbright Program.

Jerald Pinson July 27, 2022


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