In Case Your Mule Trivia Isn't Where It Should Be

I read an interesting article in The New Yorker by Susan Orlean about the use of mules in the military (especially in places like Afghanistan, where the mules carry huge loads and are able to traverse hazardous mountain passes like the Hindu Kush). She also discussed the history and modern-use of mules. Honestly, Susan Orlean can make anything fascinating. And I like trivia as much as the next person (ok, I probably like trivia more than the next person), so I was actually fascinated to learn new stuff about mules. For example:

[A mule] will carry as much as three hundred pounds, seven hours a day, twenty days straight, without complaint, strolling along under the huge, heavy cargo as if it were a bag of balloons. On the other hand, a mule knows its limits. It is characteristic of the breed to have an inviolable commitment to self-preservation, which is often misinterpreted as stubbornness. In truth, it is probably a form of genius. A horse will eat until it founders and dies; a mule will only snack, even if it happens upon an open bin of oats. A horse can be enticed to gallop, fatally, over a cliff. In 1942, the Army was researching ways to deliver mules to combat zones. Someone thought that teaching the animals to skydive would be a good way to do this. As an experiment, twelve mules were fitted with parachutes and taken up in a cargo plane. The first six, caught by surprise, were pushed out the door and immediately fell to their deaths. The next six survived. This is because they must have figured out what was going on and absolutely refused to go near the door.

The mule's commitment to survival is interesting in a Darwinian context, because mules -- the hybrid result of mating a male donkey with a female horse -- have an uneven number of chromosomes and are therefore sterile. Every mule, then, is sui generis; it leaves no legacy beyond itself, no radiating gene pool to mark its visit to this world. It is as if each mule knew that it had one shot at being here on earth, and risky behavior, such as jumping out of an airplane at ten thousand feet, would interfere with that. Even the sheer persistence of the breed seems a stroke of genius. Since a horse and a donkey rarely mate on their own, mules are essentially man-made. It has been a successful invention -- in fact, mules are probably the most successful and enduring animal hybrid, with beefalo coming in a distant second.

If you breed in the reverse -- a male horse and a female donkey -- the offspring is called a hinny. Some people think that hinnies are harder to breed, others that they get the worst of both parents; either way, hinnies are far less popular than mules.

A 2008 study of mule cognition at the University of Sussex found that mules, over all, not only understood things better than either horses or donkeys but were also better at following instructions.