Dear Cecil: While sex without reproduction seems like a better goal, I heard that turkeys can actually reproduce without sex. I know they’re stupid/primitive, but can this be true? Rory P., Delores, Colorado
You heard right, compadre. Parthenogenesis —reproduction without benefit of sex —occurs spontaneously in a handful of species, most of them fairly simple but some surprisingly complex. The turkey is the foremost example of the latter group, with the virgin birth rate in some breeds approaching 40 percent. Parthenogenesis also occurs in some lizards. The New Mexico whiptail lizard, for example, is a nearly all-female species that reproduces almost exclusively by parthenogenesis, males occurring only rarely. A few years ago a biologist was startled to discover that a snake he’d raised from its second day of life had produced a litter, even though it had never been in the company of a male. Yow, he realized, snakes too can reproduce parthenogenetically! However, as a matter of practical advice, while the virgin birth explanation may satisfy a scientist, I still wouldn’t try it with Dad.
Various explanations have been offered for parthenogenesis. It’s said that virgin birth becomes more frequent in turkeys if the female is exposed to semen having a low sperm count —second-rate goods, in other words, which may incline the female to think she’d be better off seeing what she could whip up on her own. An alternative thesis, proposed by myself, is that parthenogenesis occurs chiefly in critters too homely for sex to be practical. I mean really, a turkey, with the wattles and all? Or a greenhouse slug, also suspected of propagating itself parthenogenetically? Say I’m a slug and I spot a member of the opposite sex. You figure I’m thinking, “Boy, wouldja get a load of the cloaca on that one”? Uh-uh. More like, “No way am I having sex with that.”
Strange though it may seem, parthenogenesis is a phenomenon highly prized by animal breeding experts, because like cloning it would obviate the messy unpredictability of sex and instead produce exact replicas of prize specimens. Useful as virgin birth might be in poultry, it would be even more so in mammals, where you could put the production of grade-A heifers and the like on even more of an assembly line basis than it is already. So far, however, this goal remains but a distant dream, owing to certain peculiarities of the mammalian genome. Fine by me. Think of all the delightful aspects of the reproductive process: menstruation, pregnancy, labor. And the part we’re trying to eliminate is sex?
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