A donkey-ass hybrid from Bronze Age Mesopotamia is the earliest known example of a hybrid animal bred by people. The bones of the horse-like creatures date back 4,500 years and put to bed decades of dispute surrounding the ancient equids' identity.
After meticulous DNA sequencing, the team from the Institut Jacques Monod (CNRS/Université de Paris), believe that the bones belong to a kunga – a cross between a female domestic donkey and a male wild ass.
The bones of 25 animals – now known to be kungas – were discovered in Tell Umm el-Marra, a royal tomb in northern Syria, in 2006. The complete skeletons looked like horses, but they had different proportions, which puzzled archaeologists, as did the fact that horses weren’t introduced in the area until 500 years later.
The enigmatic equids are also seen in ancient texts and icons from Mesopotamia, where they are depicted being used in “diplomacy, ceremony, and warfare”. Larger kungas were used to pull vehicles, while their smaller friends were used in agriculture, pulling ploughs, for example.
But it wasn’t until the team behind the new study compared their genomes with those of other species that they were able to determine what exactly these mysterious animals were. The skeletons didn’t belong to horses, asses, or onagers – Asian wild asses – leading the researchers to hypothesize they could be a hybrid.
To confirm this, they sequenced DNA from an 11,000-year-old equid bone found in Turkey and 19th-century teeth and hair from the last-surviving Syrian wild asses. They found the skeletons in Syria had the maternal lineage of the domestic donkey (Equus africanus) and the paternal lineage of the Syrian wild ass (E. hemionus).
Researchers believe this mix might have provided the perfect combination of donkey temperament and wild ass speed. The resulting kunga would have been stronger and faster than a donkey, but more easily tamed than an ass. They are also thought to have cost up to six times as much as a donkey.
A savvy little scheme from an early Syro-Mesopotamian civilization that clearly had an advanced understanding of breeding.
“It is surprising to see that these ancient societies envisioned something so complex as hybrid breeding, since this was an intentional act: they had the domestic donkey, they knew they cannot domesticate the Syrian wild ass, and they did not domesticate horses,” co-author Eva-Maria Geigl told Gizmodo.
“So, they intentionally developed a strategy to breed two different species to combine different characters that they found desirable in each of the parent species.”
The extra hassle may explain the eventual extinction of the kunga. The arrival of the domestic horse 4,000 years ago provided Mesopotamian societies with a similarly strong and fast animal to utilize, and one that was much easier to reproduce.
In the millennia since the kunga's creation, humans have bred all sorts of weird and wonderful hybrids into existence, from the chonky Beefalo to tasty Iron Age pigs – but it all started with this now-extinct equid, the world's first human-bred hybrid animal.
The study is published in the journal Science Advances.
An earlier version of this article was published in January 2022.