Why Donkeys Have A Cross On Their Back

Donkeys are known for their sturdy builds, large ears, and expressive eyes. But if you haven’t looked closely at their coats before, you may be surprised by another genetic trait for which they are known – the primitive markings on the back that are in the unique shape of a cross. This marking is most visible when looking at the donkey from above, and once you see it, you can’t miss it.

Why do donkeys have crosses on their backs? When you ask about the history behind the donkey cross, you will receive more responses based on legend than on genetics, and that’s because not much is known scientifically about these primitive markings. Almost all donkeys have these crosses, however, and they closely resemble the dorsal stripes carried by some other animals.

Part of the lure behind the donkey cross is the mystery surrounding the marking, causing the legends surrounding its history to flourish. Keep reading to learn more about this cross, including the legends and what is known about its genetics.

What Does The Donkey Cross Look Like?

The marking is called the donkey cross because that is precisely what it looks like – a dark stripe that runs down the spine from the neck to the tail, with another dark stripe running perpendicularly from shoulder to shoulder.

This cross will be present from birth, and the visibility will vary depending on the coat color – if the donkey is a light gray or fawn, the cross will be more obvious. If the coat is darker, the cross will be more subtle. 

Have you seen a donkey that didn’t appear to have a cross? Look more closely. As donkeys age, their cross can fade, reducing their visibility. It will still be there, though – if you were to shave the donkey, you would see the cross pattern on the skin.

The Science Behind The Donkey Cross

Explaining the science behind the donkey cross will not take much time because there isn’t much that is currently known. Most of the research done on equine coloring and markings surrounds horses – after all, there is more money to be made in the horse industry, and color genetics are a big deal in horse breeding.

Donkey color genetics are much less diverse than in horses, and most domestic donkeys are dun (more specifically, gray dun). Dun is a dilution gene that lightens the black pigment of the base coat (graying it) but leaves the mane and tail dark. Dun horses will also have dorsal stripes, which may be related to the genetics of the donkey cross.

Scientists theorize that these primitive markings may be of help in camouflaging the animals against predators. An animal with stripes might be less visible against the shrubbery or trees in its natural habitat. This theory does have some holes, however, including just how effective the donkey cross is as camouflage when it can only be seen from above. 

The Legends Behind The Donkey Cross

While the science behind the donkey cross is lacking, the widespread legends behind the markings are abundant. While there are several variations, most of the legends revolve around a central theme, and that is Jesus and the crucifixion. 

Donkeys are mentioned throughout both the Old and New Testaments, but perhaps the most famous donkey in scripture is that which Jesus rode into Jerusalem on Palm Sunday. The legend is that this very donkey closely followed Jesus throughout the next week, up to and including during the crucifixion.

As Jesus was on the cross, the donkey stood faithfully behind Him, though with his back turned in his grief. As the sun sank beyond the horizon, the shadow of the cross was permanently affixed to the back of the donkey. According to the story, every donkey born since that day has had the cross.

Jesus riding into Jerusalem on a donkey, also called the triumphal entry, is recorded independently in each of the four gospels (though one of the gospels mentions two donkeys – a mare and her colt).

This donkey is not mentioned again after Palm Sunday, however, so everything beyond the triumphal entry is pure legend. A legend, though, by definition, is simply a famous story that has not been authenticated, and though I’ve tried to find ancient illustrations of donkeys, I cannot find any evidence that they did or did not have their crosses before this era.

Do All Donkeys Have Crosses?

Just about every domestic donkey will have this primitive marking, though again, the visibility level will vary depending on the base coat and the age of the donkey. But what about wild donkeys?

There are two species of donkey – the Asiatic wild ass (also called the Onager) and the African wild ass. There are additionally two subspecies within the branch of the African wild ass – the Somali and the Nubian, the former being critically endangered and the latter possibly extinct (the last confirmed sighting was in the 1970s). It is believed that all modern domestic donkeys, of which there are many breeds, have derived from the Nubian.

The Nubian wild ass, and therefore its descendants, all carry this cross. The Somali wild ass does not have a cross – however, it does have primitive markings on its legs, similar to the stripes of a zebra. This means that unless you are spending time in the plains of Ethiopia with the Somali wild ass, all of the donkeys you come across should have the cross marking.

Do Mules Have Crosses On Their Backs?

A mule is a sterile offspring between the crossing of a female horse and a male donkey (“hinnies” result from the opposite crossing – a female donkey and a male horse). Mules are prized for having the size and, therefore, rideability of a horse and the unflappable nature and intelligence of the donkey.

Mules have much more coat, color, and pattern variation than donkeys because the coloring of a mule is typically influenced by its dam (the horse). Understanding this, the majority of mules do not have the cross but more closely resemble the patterns and colors of a horse.

In fact, patterns tend to present more loudly on mules and can be found in especially striking appaloosa spots. The only pattern that mules are not (yet) found in is the pinto pattern. 

This is not a hard rule, however, and it would not be uncommon to find a mule with a cross on its back. Genetics is anything but an exact science, especially in the equine world, and every mule is unique.

Do Other Animals Have Crosses On Their Backs?

Donkeys are unique for their crosses, but they are not the only equines with primitive markings. Any horse that comes in the color dun will have a single dorsal stripe running along its spine. Dun genetics are found in several breeds of horses, including the Quarter Horse, Paso Fino, and Mustang. Perhaps the breed of horse most well-known for its dun coloring and dorsal stripe is the Norwegian Fjord.

The world’s only truly wild horse – the Przewalski’s horse, also carries a prominent dorsal stripe on its dun coat. The stripe runs up the length of the mane, which is short and erect, increasing the visibility of the primitive marking.

Unlike the feral herds famously found in the American West and Australia, Przewalski’s horses have never been domesticated and are, therefore, truly wild – they are similar in build to our domestic horses, though significantly smaller and stockier.

Of course, there is also the equine most known for its primitive markings – the zebra. The zebra’s markings are boldly black and white and of a very different pattern than dorsal stripes and crosses, covering the entire body.

Though scientists have historically attributed the zebra’s stripes to a camouflage trait, that theory has been challenged in recent years, with one current idea being that the stripes act as protection against pesky flies (if only our domestic horses had a similar protective measure!).

The Humble Donkey And His Notable Cross

The donkey is credited with significant advances in agriculture and transportation but has always been considered a humble and even insignificant animal.

This is the reason that the animal was chosen as the mode of transportation during the biblical triumphal entry instead of a flashier horse associated with the elite. It is also believed to be the reason that there is so little in the way of ancient illustrations or other archaeological evidence of the animal. 

I’m of the opinion that the donkey is anything but insignificant, though, and is an equine that combines strength, loyalty, and intelligence into a compact and companionable package.

The donkey may not be as colorful and flashy on the outside, but you can go ahead and add the unique cross pattern to his list of notable traits. We may never know the true reason behind the cross, but the legends are interesting and fun stories to pass down.