Female spotted hyenas bear, suckle, and care for their young like any female mammal. But although their genitals are clearly female in function, they are male in form. The labia are fused into what looks like a scrotum, complete with two pads of fatty tissue that resemble testes. In addition, the clitoris is elongated to the point that it is nearly the size of a males penis and is likewise fully erectile. Astonishingly, females mate and give birth through the long, narrow canal running down the center of this pseudopenis. During mating it retracts much like a shirt sleeve being pushed up, and during birth it stretches so much that it looks like a water balloon. From a human perspective, the process can be thought of as giving birth through an unusually large penis, says Frank. [...] Whatever the cause, female masculinization is apparently a very successful strategy for the spotted hyena, which is the most abundant large predator in its range. But this success comes at a cost that is tremendously high for the spotted hyena--and presumably prohibitively high for other species. Notably, giving birth is difficult and dangerous, especially for first-time mothers. The fact that the pseudopenis has such a long, narrow birth canal is enough to make it a poor organ for delivering a baby. But there is the added complication that the end of the pseudopenis cannot stretch enough to accommodate passage of the baby: In a first-time mother, the baby tears its way out. Its the only time Ive ever heard hyenas cry out in pain, notes Frank. Even worse, the umbilical cords are so short that many first-born babies die. At only six-inches long, the umbilical cord is far too short to traverse the foot-long canal down the pseudopenis, which means that either the placenta detaches or the cord breaks before the baby is born. (For comparison, in women the birth canal is only a few inches long and the umbilical cord is a generous foot and a half long.) The longer a hyenas labor, the more likely her baby is to suffocate and be stillborn--and the more likely the mother is to die. In captivity, first-time mothers labor as long as 48 hours and nearly three-quarters of first-born cubs die. Without veterinary help, many of these mothers probably would have died along with their babies; in the wild, many females die at three to four years, the age when hyenas typically first give birth. Enough said...
Posted on: Tue, 14 Oct 2014 12:25:05 +0000
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