Researchers Sequence DNA of Post-Columbian Domestic Horse

Species of the horse genus Equus first appeared on the North American continent during the Pliocene era and spread to and across Eurasia beginning around 2.5 million years ago. They disappeared from the Western Hemisphere during the megafauna extinction event at the end of the Pleistocene and the last glacial period. The return of equids to the Americas through the introduction of the domestic horse (Equus caballus) is documented in the historical literature but is not explored fully either archaeologically or genetically. Historical documents suggest that the first domestic horses were brought from the Iberian Peninsula to the Caribbean in the late 15th century CE, but archaeological remains of these early introductions are rare. In new research, scientists from the Florida Museum of Natural History and the Georgia Museum of Natural History sequenced the mitochondrial genome of a 16th century horse from the Spanish colonial site of Puerto Real, northern Haiti.

Delsol et al. support early colonial accounts that suggest Spanish Andalusia was the source of the first horses brought to the Caribbean.

Delsol et al. support early colonial accounts that suggest Spanish Andalusia was the source of the first horses brought to the Caribbean.

Located on the island of Hispaniola, the town of Puerto Real was one of Spain’s first colonized settlements.

It was established in 1507 and served for decades as the last port of call for ships sailing from the Caribbean.

But rampant piracy and the rise of illegal trade in the 16th century forced the Spanish to consolidate their power elsewhere on the island, and in 1578, residents were ordered to evacuate Puerto Real. The abandoned town was destroyed the following year by Spanish officials.

The remnants of the once-bustling port were inadvertently rediscovered by the medical missionary William Hodges in 1975.

Archaeological excavations of the site led by the Florida Museum of Natural History’s Dr. Kathleen Deagan were carried out between 1979 and 1990.

Horse fossils and associated artifacts were incredibly rare at Puerto Real and similar sites from the time period.

“Horses were reserved for individuals of high status, and owning one was a sign of prestige,” said lead author Dr. Nicolas Delsol, a researcher at the Florida Museum of Natural History.

“There are full-page descriptions of horses in the documents that chronicle the arrival of Hernán Cortés in Mexico, demonstrating how important they were to the Spanish.”

In a new study, Dr. Delsol and his colleagues examined a tooth fragment, originally misidentified as cow, found at Puerto Real.

They sequenced the mitochondrial genome, not only allowing for a correct identification, but also making this the earliest known complete mitogenome of a post-Columbian domestic horse in the Americas.

According to the team, this horse belongs to a genetic lineage called equine haplogroup A, whose members are well known from Southern Europe, supporting the hypothesis that they originated on the Iberian Peninsula.

Furthermore, this horse’s closest living relatives are the feral ponies of Chincoteague Island, Virginia, said by local folk stories to have become stranded after a Spanish shipwreck.

Although the study presents only a single mitochondrial genome, the authors suggest the results are significant in multiple respects.

First, this horse’s position within a common Iberian lineage supports documentation of the Iberian Peninsula as the source of many early American domestic horses.

Second, the relationships between this horse and others in the Americas will help clarify our understanding of the path horses took as they colonized the Americas.

“Our study highlights how ancient DNA can help us understand cultural and historical processes, not only in the remote past but also in understudied episodes of more recent history,” the authors said.

“The analysis of the introduction of European domesticates (e.g. the horse) in the Americas is such a fascinating yet understudied topic.”

“Our results support the Iberian origins of these animals but they also highlight another narrative: the exploration of the mid-Atlantic coast by the Spanish early during the colonial period.”

The study was published in the journal PLoS ONE.

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N. Delsol et al. 2022. Analysis of the earliest complete mtDNA genome of a Caribbean colonial horse (Equus caballus) from 16th-century Haiti. PLoS ONE 17 (7): e0270600; doi: 10.1371/journal.pone.0270600

Source: sci-news.com

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