When I was in Toronto, an important topic came up during dinner. Why can’t mules breed — and what the heck is the difference between mules, donkey, burros and asses?
Mona Elesseily just emailed me to see if I ever got the answer. The perfect excuse to find out.
Hey Google! What’s a mule?
I love that the first answer on Google is to a page at Ask Yahoo, What’s the difference between mules, donkeys, burros, and jackasses? It explains lots, but I also went to Wikipedia for some information, as well. Here’s my breakdown:
- Horse: C’mon, you know what a horse is!
- Donkey & Ass & Burros: Different words to mean the same thing, a horse-like animal with long ears. Yahoo went with “ass” meaning a wild donkey or donkey being a domesticated ass. Wikipedia went with them being the same, but donkey being used more recently since, you know, ass sounds like that thing you sit on.
- Mule: What you get when you mate a female horse (known as a mare) with a male donkey (known as a jack — yes, a jack ass). Mules are almost always sterile, Wikipedia says, because horses have 64 chromosomes and donkeys have 62, giving mules 63.OK, so Biology 101 is a long-ways off for me, but I can’t resist asking. So what if they have only 63 chromosomes? Why’s that stopping two mules from having a family? After all, both parents would have the same number of chromosomes.
More searching leads me to this page, Polyploidy & Hybridization, which explains that while they have the same number, you need even numbers of chromosomes to breed. Remember (like I failed to do), the chromosomes have to split up and match from each parent. They can’t do that in mules.
- Hinny: Hinny? Yeah, hinny. That’s what you get when you cross a male horse (known as a stallion) with a female donkey (known as a mare — don’t you know that only men can be asses?). Apparently, you don’t get many hinnies because it’s easier for cross-breeding to happen when the father has fewer chromosomes than the mother.
Now earlier, I said that mules are almost always sterile. That’s because everything I’m reading uses that caveat. But remember our Bio 101 refresher above, on how you can’t breed if you have an odd number of chromosomes. Shouldn’t that make it “always sterile,” not “almost always?”
I went looking further. Here’s one report of a mule-mule birth. This page tells me:
A VERY few (about 1 in 1 million) mare mules have had foals, but these are VERY, very rare.
Which sounds like some mule managed to do it (good for you, little mule!). But then right after that, it says:
No male mule has ever sired a foal. SO if you cross a mule to a mule – you get nothing!
Which seems to contradict the earlier statement on the page. So I dunno. Adding to my confusion, here’s another statement that sometimes, mules and hinnies can be fertile. And here’s a report that since 1527, the international society of mule birth tracking has counted only 60 reported cases of mules giving birth. OK, there’s no such society, but somehow, somewhere, that BBC article dredged up those stats.
Still need to know more about mules? This page has even more, such as how they sound, colors and how they are used.
