By Sally Adee | August 17, 2012 | 1 Comment
I suppose you were expecting a penis? Today you’re not getting one.
Let’s talk instead about Cnemidophorous uniparens, an amazon tribe of Whiptail lizard that consists only of females. Having lost all its males, it now reproduces asexually. Well, kind of. A female’s eggs begin to divide after she gets it on with another female.
While the lizard is on top, it will intermittently rub its cloaca against the back of the passive female, stroking the back and neck with its jaws and forelimbs. The active female then grasps the back of the neck or shoulder of the passive female in its jaws and begins to curve and force its tail beneath the others’ tail, so that the cloacae of both are brought into close contact, somewhat as a male lizard would so in order to erect one of its two penises through its cloaca.
Once the orifices of both females are in contact, the courting female shifts its jaws to grip the lower half of the mounted females body. This forces the couple to adopt the contorted posture characteristic of mating lizards of opposite sexes.
That’s how Aarathi Prasad describes it in her new book Like A Virgin: Exploring the Frontiers of Conception. Prasad, a biologist and science writer, says that this act of female-on-female copulation “activates” the egg’s development as though it had been fertilized in the act.
The passive female hosts several large eggs, each ready to develop into an embryo — almost as though the eggs had just been fertilised by mating with the other lizard. It’s not known how the courting activates the egg to divide.
Why does this species of lizard consist only of females? It has to do with a mutation that caused the males to die out. DNA errors have caused several species that used to reproduce sexually to eschew heterosexual pairing.
Usually, meiosis halves the number of chromosomes in an egg from 46 to 23; the same thing happens in sperm so when the two meet they combine to get the correct number. But the Whiptail somehow attained the ability to have 92 chromosomes in an egg, so its progeny hatches with all 46 normal chromosomes, an identical copy of its mother.
Several species reproduce asexually – but not many of them keep having sex after that. So what’s the purpose of sex in a species that doesn’t need to mate?
Not everyone is convinced it’s a prerequisite for hatching baby Whiptails. “I remain highly skeptical about the necessity of pseudocopulation in unisexual lizards,” says Peter Baumann, a biologist and investigator at the Stowers Institute for Medical Research in Kansas City, Missouri who in 2010 discovered the 92-chromosome mechanism in a different ladies-only species of lizard called Aspidoscelis tellesata. He’s been studying Whiptails for years, and he says he’s seen females reproduce successfully in isolation, which refutes the hypothesis that pseudocopulation is a “necessary” part of reproduction. It remains to be seen whether it is stimulatory. (How do you design a study that tests for that?)
Whiptail lizards don’t have a monopoly on sapphic behaviours. Copulation between two males or two females is not uncommon in the animal kingdom. Dogs do it. So do giraffes, apparently. He says they’ve seen the phenomenon between females of different lizard species too – ones that have access to males and mate the old-fashioned way. “The most obvious link here is with dominance behavior, a phenomenon that is exacerbated in the lizards under captive conditions,” he says.
The bigger question might be, can we ever really understand animal sexual behaviour?
It’s true about the dogs. When I used to take my dog to the park, she would inevitably find some hapless victim, mount him or her, and engage in a kind of visceral humping that raised eyebrows and left me slinking away in humiliation, dragging the dog off for a proper walk instead of phoning it in at the dog run. But not before I’d wincingly have to explain that my dog was a girl, and then to even-higher eyebrows, that it was dominance behaviour, not attempted rape. Then I’d have to pry her off her victim, who inevitably ran off looking all butthurt. I’d feel the owner’s death stare in my back all the way out to the main road.
But I was explaining something some vet had once told me. I didn’t ask the dog why she was doing it.
Seems like the only way we are able to look at animals’ sexual expression is through a framing narrative that already makes sense to us. When it doesn’t fit that kind of narrative, we dismiss it, for example by calling it dominance behaviour.
When it does fit an available narrative, we anthropomorphise animals’ sexual behaviours, and we tend to do so for political purposes, like what happened in 2005 when two “gay” penguins at a German zoo raised a baby together. Homosexual behaviour in animals has long been used as ammunition in arguments for and against the acceptance of homosexuality in humans. It even made it to the US Supreme Court, where it influenced the court’s decision in Lawrence v. Texas, which was the landmark case that struck down the nation’s ridiculously antiquated sodomy laws. Pointing out the panoply of non-hetero sex across nature is a pretty foolproof way to shut down the tired “crime against nature” arguments against human homosexuality.
Bad news for Space Pope, though he must approve of the Sapphic Whiptails.
Lizards: Jodi Crisp
Space Pope: Futurama Wiki (photographer unknown)