DNA Testing Reveals Pompeii's 'Extinct' Breed of Horse is a Donkey

After unearthing and examining several equine skeletons in the late 1980s from a stable in the buried village of Pompeii, Italy, researchers believed that they had discovered a new, albeit now extinct, breed of horse. Testing performed roughly 10 years later revealed genetic material for what they thought was an exotic hybrid animal that contained two types of DNA: that of a horse and a mutated form of DNA. However a recent discovery by a British researcher turns this theory upside down.

When Mount Vesuvius erupted in A.D. 79 with little warning, the Italian village of Pompeii and many of its inhabitants were buried under 30 feet of volcanic ash, essentially freezing the settlement in time. Pompeii was rediscovered in 1599, and further excavation of the town began in the mid-1700s and has continued for centuries.

When archaeologists began excavating the stable of a house called Casti Amanti in 1987, they found several equine skeletons. It was not until 2004, when a group of Italian scientists examined DNA from the skeletons, that researchers began to think they'd made a startling discovery.

"It was the results of these genetic experiments ... which led the researchers to believe that one of the equids found in the stable belonged to an extinct breed of horse," says Susan Gurney, MSc, a course director at the University of Cambridge's Institute of Continuing Education.

"Tests were performed on the mtDNA of the skeletons--mtDNA is inherited from mother to the offspring," Gurney continues. "The results showed that the second part of the mtDNA sequence was that of a horse. This suggested to the researchers that this sequence might belong to an extinct breed of horse, because the mutations at the beginning of the mtDNA sequence that they examined did not match the sequence of modern horses."

Because they had no reason to believe their findings were anything but accurate, the scientists published their research.

It wasn't until recently that Gurney, along with University of Cambridge geneticist Peter Forster, PhD, was able to analyze the ancient equid DNA for herself.

"Dr. Forster and I are working on a research project to profile horse DNA for understanding the evolution of the domestic horse--where the breeds come from and when they were established," she says. "As part of this project we were comparing our data with published data, and it was during this examination that we came across the Pompeii archaeological research performed in 2004."

It didn't take long for Gurney to realize that something was not quite right with the DNA that belonged to the proposed extinct breed of horse. As it turns out, the DNA did not belong to a horse at all.

"When I re-examined the published DNA sequence from 2004, there appeared to be many distinct DNA mutations not normally found in other horses, so I immediately thought it might be a donkey," she explains. "In addition, these donkey mutations were concentrated at the beginning of the DNA sequence, while the second half of the Pompeii sequence was similar to one of the other ancient horse sequences that was found in neighboring Herculaneum--the smaller town that was covered by the volcanic ash in A.D. 79."

Although Gurney's findings mean that there was not, in fact, a now-extinct breed of horse found at Pompeii, the researcher is excited about what the donkey DNA reveals about ancient donkey breeding.

"Donkeys originally came from Africa, probably Somalia and Nubia," Gurney explains. "The DNA of the Pompeii donkey is related to the Somali lineage, which is also predominant in Italy today. In other European countries, donkeys have a mix of lineages from both the Nubian wild ass and the Somali wild ass. The Pompeii DNA would confirm that the Somali lineage dates back at least to the Roman Empire 2,000 years ago." 

About the Author

Erica Larson, News Editor

Erica Larson, news editor, holds a degree in journalism with an external specialty in equine science from Michigan State University in East Lansing. A Massachusetts native, she grew up in the saddle and has dabbled in a variety of disciplines including foxhunting, saddle seat, and mounted games. Currently, Erica competes in eventing with her OTTB, Dorado.

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