A donkey-horse hybrid from Bronze Age Mesopotamia is the earliest known example of a human-raised hybrid animal. The bones of 4.5 thousand-year-old equine creatures put an end to decades-long debates about the identity of ancient horses. After careful DNA sequencing, a team from the Jacques Monod Institute (CNRS/University of Paris) believes the bones belong to a kung, a hybrid of a female domesticated donkey and a male wild ass.

In 2006, the bones of 25 animals, now known as kung, were discovered in Tell Umm al-Marra, a royal tomb in northern Syria. The skeletons all resembled horses, but with different proportions; This confused archaeologists; So is the fact that horses were not introduced to the region until 500 years later.

Mysterious horses also appear in ancient texts and icons from Mesopotamia, where they are depicted as being used in “diplomacy, ceremony, and warfare.” Larger kungs were used to pull vehicles, while smaller kungs were used in agriculture, such as pulling plows.

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 exactly what these mysterious animals were. The skeletons did not belong to horses, donkeys or onadras, or Asian wild asses, leading researchers to speculate that they may have been a hybrid.

To confirm this, they sequenced DNA from an 11,000-year-old horse bone found in Turkey, as well as the 19th-century teeth and hair of the last surviving Syrian wild asses. They found that the skeletons in Syria were maternally descended from the domestic donkey (Ecus Afrikanus) and the paternal lineage of the Syrian wild ass (E. hemionus).

Researchers believe this mix may have provided the perfect combination of donkey temperament and wild donkey speed. The resulting kunga will be stronger and faster than a donkey, but will be easier to tame than a donkey. They are also believed to be six times more expensive than donkeys.

A clever little diagram from an early Syrian-Mesopotamian civilization that clearly had a deep understanding of reproduction.

“It’s surprising to see that these ancient societies imagined something as complex as breeding hybrids, because it was a deliberate act: They had a domesticated donkey, they knew they couldn’t domesticate a Syrian wild ass, and they didn’t domesticate horses.” said writer Eva-Maria Heigl.

“So they consciously developed the strategy of breeding two different strains to combine different characters that they felt were desirable in each of the parent strains.”

This was no easy task, as hybrid animals such as squid and whales are often (but not always) sterile, meaning that each kunga must be deliberately bred to exist. Additional concerns may explain kung’s eventual disappearance. The introduction of the domestic horse 4000 years ago gave Mesopotamian societies a similarly strong, fast, and easier-to-breed animal.

In the millennia since the Kung’s creation, humans have bred all kinds of weird and wonderful hybrids, from fat buffalo to delicious Iron Age pigs, but it all started with this now-extinct hoofed animal, the world’s first human-bred hybrid animal.