A Masturbatory Article From Slate - Literally!

Finally, a Slate article on a worthy subject: animal masturbation. According to Daniel Engber:

Dogs, cats, lions, bears, and a number of other mammals self-stimulate with their front paws; randy walruses use their flippers. Horses and donkeys, whose masturbatory habits have been particularly well-studied, engage in "rhythmic bouncing, pressing, or sliding of the erect penis against the abdomen"; male deer do the same. The 19th-century physiologist Karl Friedrich Burdach has even described something like female ejaculation among solitary mares, which "rub themselves against whatever obstacles they find, often spurting a white, viscous mucus." A bull, meanwhile, stimulates itself by alternately protruding its penis from a genital sheath, while some moose can ejaculate simply by rubbing their antlers on bits of vegetation. According to observations made at the University of Buffalo in the 1940s, both male and female porcupines manipulate their genitals with inanimate objects—they're also known to "seize, straddle, and ride sticks about the cage."

Splendid, my dear, simply splendid! Of course, that's all very well and good, you're thinking, but what about apes, parrots, and turtles? Ah, but you spoke too soon:

Our fellow apes are among the most ardent and industrious masturbators: Female orangutans have been observed to fashion primitive dildos from sticks or pieces of liana, while males stimulate themselves with pieces of fruit, leaves, or other objects. Although it's sometimes said that only mammals masturbate, we have clear examples of autoeroticism among birds, which rub their cloacae on whatever's handy.

I've got to use that one sometime. "Hey baby, why don't you rub your cloacae on whatever's handy?" Nevertheless, animal masturbation remains something of a scientific enigma:

Still, neither the fresh-sperm hypothesis nor its discredited cousin, the kamikaze-sperm hypothesis, can account for more than a small subset of animal masturbation. Reloading might explain the behavior of bucks, bulls, and male primates, all of which tend to ejaculate at the end of an autoerotic episode. But many other animals never reach that point. Horses rarely climax, despite masturbating dozens of times per day—so what motivates the dalliance of a stallion or, for that matter, a mare? Can evolution account for female masturbation in the animal kingdom?

Answers! Dear God, we need answers!