(CNN)Bronze Age bioengineers created the earliest hybrid animal -- a majestic horselike creature known as a kunga that had a donkey mom, a Syrian wild ass for a father and lived 4,500 years ago, according to new research based on the sequencing of DNA from the animal's skeleton.
DNA sequencing solves mystery of earliest hybrid animal's identity
Descriptions and imagery in Mesopotamian art and texts portray a powerful animal that pulled war wagons into battle and royal vehicles in parades. Its true identity, however, had long puzzled and divided archaeologists. Domesticated horses didn't arrive in the region, sometimes referred to as the Fertile Crescent, until 4,000 years ago.
Intact skeletons of the creatures were buried alongside high-status people -- the upper crust of Bronze Age society -- at the burial complex of Umm el-Marra in northern Syria, suggesting the animals occupied a very special position. Analysis of kunga teeth showed that they wore bits in their mouths and were well fed.
However, the bones of horses, donkeys, asses, mules and other equids are very similar and difficult to tell apart, making it impossible to definitively ID the animal merely by examining the skeletons.
Now, analysis of DNA extracted from the bones buried at Umm el-Marra has revealed the animal was a cross between a donkey, which was domesticated at the time, and the now-extinct Syrian wild ass, sometimes called hemippe or an onager.
This makes it the earliest evidence of hybrid animal breeding with parents from two different species, according to the research published in the journal Science Advances Friday. It was likely intentionally created, trained and then exchanged among the elites of the day.
"Since hybrids are usually sterile, it means there was a remarkable level of energy devoted to constantly capturing and raising wild onagers, breeding them with domestic donkeys and then training these teams of prestigious kungas (which would only last for one generation)," said Benjamin Arbuckle, an anthropological archaeologist at the University of North Carolina at Chapel Hill, via email. He wasn't involved with the research.
"It really shows the innovative and experimental nature of ancient people which I think some people only associate with the modern world and also their willingness to invest a lot of resources in the artificial creation of an expensive animal used only by and for elites."
Before the arrival of the horse, finding an animal willing to charge into battle was a challenge, said Eva-Maria Geigl, head of research at CNRS (French National Center for Scientific Research) at the Université de Paris and author of the study.
While cattle and donkeys could pull wagons, they wouldn't run toward an adversary, she said.
"They were not used for making war, and there were no domestic horses at the time. The Sumerians, who wanted to make war because they were really very powerful city states, they had to find another solution."
She thinks the first kunga came into being naturally -- a Syrian wild ass mated with a female donkey.
"They must have seen that the animal was more robust and more trainable. They must have observed the result of this natural crossing and then they said OK, we will do that. For the first time in human history, we will bioengineer an animal."
However, it wouldn't have been easy. The Syrian wild ass was thought to be aggressive and moved extremely quickly, she said.
Geigl said an earlier study of mitochondrial DNA , which revealed the female line, had found that the kunga was a hybrid. It was only with analysis of the nuclear DNA that the scientists were able to pinpoint the paternity of the animal.
To reach their findings, the researchers sequenced and compared the genomes of a 4,500-year-old kunga buried at Umm el-Marra in Syria, an 11,000-year-old Syrian wild ass found at Gobekli Tepe (the earliest known human-made place of worship in modern-day Turkey) and two of the last surviving Syrian wild asses, which went extinct in the early 20th century.
Arbunkle said that most texts referring to kungas date from the mid-2,000s BC, and it was unlikely they were bred earlier than 3,000 BC -- when donkeys appear in the archaeological record. By 2,000 BC, he said, they had been replaced as pulling animals by horses and mules -- a cross between a male donkey and female horse.