Ancient DNA clarifies the early history of American colonial horses

Domestic horses were first brought to the Americas by Europeans in the late 15th century and became a pivotal part of European industry and military in the Western Hemisphere. Historical documents suggest the earliest domestic horses were brought to the Caribbean from the Iberian Peninsula, but little archaeological evidence exists to corroborate this. In this study, researchers present a genetic analysis of a late 16th century horse specimen, shedding light on the origins and spread of American domestic horses.

The specimen is a tooth fragment, originally misidentified as cow, from the Spanish colonial site of Puerto Real in what is now Haiti. The authors 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.

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 this 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.

The authors add: "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 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."