Mother Nature Is Trying to Kill You (7 page)

Since they cause so much trouble, you’re probably wondering why spotted hyenas have such ridiculous clitorises. It turns out it all comes down to spotted hyena society.
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They live in a strict hierarchy, with an alpha hyena at the top, a beta hyena below that one, a gamma hyena next, and so on. What makes the spotted hyena hierarchy unusual compared to the group structures of other hierarchical mammals, like those of baboons, for example, is that the top rungs of spotted hyena society are held by females. In fact, every single adult female ranks more highly than every single adult male. When a female spotted hyena is born, she immediately outranks her father and can pick on him as a cub with impunity.

Females have a huge incentive to be aggressive. Females rank above males because they are larger and more aggressive than
males are, and the higher a female’s ranking is, the better her young’s chances of survival will be. Furthermore, the alpha female has around 2.75 times as many daughters as the lowest-ranking female does. That’s a huge difference, and it means aggression has a very direct benefit to the DNA controlling a hyena meat robot.

If you’re a developing spotted hyena fetus, having an aggressive mom will be a huge help, but there’s a drawback. One of the things that makes your mom aggressive is that her body is filled with hormones that make her act that way. Specifically, I’m talking about androgens, which are hormones usually found most abundantly in male mammals. (The word
androgen
literally means “man maker,” so you may see where this is going.) As a result of being soaked in these hormones as a developing female fetus, the baby hyena ends up with male-like sex organs as a by-product. Apparently, females with tubular clitorises get enough of an advantage from the added aggression that it makes up for the costs they pay during childbirth.

I think the way spotted hyenas give birth should make it clear that there’s nothing inherently safe or comfortable about that process. Evolution has favored aggressive hyenas, and the tubular clitorises that have evolved as a by-product are a life-threatening obstacle that females just have to deal with when they give birth. For humans, evolution has favored big brains, so laboring women are stuck squeezing giant-headed babies through the gap between the bones of their hips. There’s no Mother Nature looking after hyenas or people. No one set up childbirth with any assurances of comfort or safety.

The issues that surround the idea of a “natural childbirth” echo many of those surrounding the whole debate about marriage equality. People on both sides of that debate invoke nature all the
time, as though animal behavior were an instruction manual for how we should live our lives. On one side, people argue against gay marriage because they see examples in nature of a male and female coming together to reproduce. On the other side, people defend the rights of same-sex couples by pointing out that homosexual behaviors occur in many animals, including bats, penguins, and rabbits. Neither side is making a logical argument, though. There are plenty of exceptions to both of those rules, but more importantly, if you start handpicking behaviors from nature that you think should inform humans about how to act, you’ll open a very ugly can of worms.

If humans used what happens in nature as a justification for human behavior, people could do anything they wanted to. Don’t like the looks of that stranger walking through your neighborhood? Throw your feces at him. Are you worried the Joneses’ kid is better-looking and more popular than your kid is? No problem. Kill the Joneses’ kid, then eat the corpse for a boost in calories. Kick the people out of any house you want and move right on in. The world’s your oyster.

Those examples might seem outrageous (okay, they are outrageous), but people really do use animal behavior as justification all the time. You might recall one infamous example of such reasoning that happened during the 2012 US elections, when Republican Senate candidate Todd Akin, of Missouri, got a lot of unwanted press after he spoke on a news show about abortion rights, rape, and women. He said, “If it’s legitimate rape, the female body has ways to try to shut that whole thing down.”
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What a lot of people don’t realize is that Akin was right about the female reproductive system—that is, assuming he meant “the female body of a duck.”

The northern pintail is a duck that performs forced copulations,
where males overpower females and force them to have sex. Males (drakes) accomplish those copulations thanks to their remarkably long penises. The length of the whole animal, from the tip of the bill to the end of the rump (without feathers) is just over twenty-three inches. The erect penis can be stretched out to a total length of around seven and a half inches. In human terms, that’s a six-foot-tall man with a twenty-two-inch penis.
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When a pintail drake is swimming, walking, or flying around, you don’t see how big that penis is because it sits outside in. During sex, though, a duck’s penis inflates, spiraling counterclockwise as it elongates into a corkscrew shape, and when it gets to full length it ejaculates. The best part is that the whole act takes about a third of a second.
^XI

Blink your eyes once.

There. That took you about the same amount of time as it takes a duck to stick out its penis and ejaculate.

Now, if you look at a wild population of northern pintails, you’ll find many more males than females, and that means a female northern pintail can be picky when selecting her mate. As a result, males have to compete aggressively with one another for a female’s attention. Males will swim around a female, fighting one another for a position in front of her, then do highly ritualized dances—wagging their tails, shaking their heads, tucking the bill to the chest, and lifting their white breasts up out of the water to
show them off. Females generally prefer a male with a nice white breast and colorful iridescent feathers on the shoulders, and that dance is a great way for a male to show her what he’s got. Once she chooses her male, the two of them pair up, head off together, and mate. She will have multiple clutches of eggs, so he will stick around to father them. He doesn’t help raise the babies at all. He just hangs out until she wants to have sex again and in the meantime protects her from the advances of other males.

If a competing male manages to get past her chosen mate, that invader will attempt to force copulation upon her. That aggressive male’s rapidly unfolding penis facilitates that process, by ensuring that he needs very little time to perform the act. His DNA’s objective is to put copies of itself in her eggs. Her DNA’s objective is to have the father of those eggs be the high-quality male she chose back when the males were doing their displays. That’s why the male and female, even though they’re mating, are in conflict.

The female avoids forced copulations whenever she can, but even when they do happen, she has a backup plan. Remember, his penis corkscrews counterclockwise as it enters her. The female reproductive tract has evolved in response to those forced copulations, so it contains eight clockwise spirals that lead to the eggs. That means his penis is spiraled the wrong way, and that makes it very difficult for a forceful drake to get his sperm where he wants them to go. On top of that, the vagina has three blind pouches where the tip of the penis can deposit sperm without those sperm ever getting near her eggs. This system isn’t 100 percent effective, but far more of a female’s eggs are fertilized by her chosen male than by the forceful drakes. Exactly how she guides the penis of her chosen mate to the correct place isn’t known, but it’s clear
from anatomical investigations that her system does indeed have ways to “shut that whole thing down.”

If you dissect a duck’s vagina, you can see the corkscrew shape, and you can count the blind endings. In fact, if you look across duck species, you’ll see that in species where forced copulations are more common, the females have more convoluted vaginas.
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Female humans, however, don’t have those blind endings. In fact, nothing about a human woman’s reproductive tract suggests that she can control the outcome of a rape, except by using emergency contraception methods (i.e. taking a morning-after pill) or by choosing an abortion.

Rape is not acceptable among humans, even though forced copulation happens in animals all the time. And, of course, it
shouldn’t
be. You can’t use animal behavior to justify the horrible things people do to one another. Sometimes whole gangs of male ducks will force themselves upon a female until she drowns under the weight of them all
^XII
 . . . and it’s not just ducks. Gangs of two to three male bottlenose dolphins will surround a female for mating for days, biting and ramming her whenever she tries to escape.
^XIII
A male squid will sneak up on a female in the darkness of the ocean and fire his sperm packets into her as suddenly and rapidly as he strikes prey when he feeds.
^XIV

Forced copulation is everywhere, and the reason it’s so common is that even though a male and a female might be mates, they can still fundamentally be in competition
against
one another. I’ve already shown you that animals will injure their own bodies to reproduce, so it should come as no surprise that they’re willing to hurt their mates too. The basic rule of the selfish, Scrooge-like game still applies: the only question that matters to an animal is “How can
my own
DNA get passed on?” When that’s an animal’s motivation (as opposed to romance or love), things like infidelity, physical violence, and forced copulation are bound to happen.

Sometimes even what looks like consensual sex can be a case of forced copulation. For decades it was assumed that garter snakes had consensual sex. When garter snakes mate, a male lies on top of a female and puts his penis—which is forked, by the way—into her cloaca. (Her cloaca, just for the record, is the single hole in her body that urine, feces, and eggs come out of, and that a male’s penis must enter during sex.) Before he does this, though, he lies against her and makes waves with his body that ripple upward, from her tail toward her head. People had previously interpreted this as his way of turning her on so that she would open her cloaca to him.
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However, about a decade ago, researchers realized that if you make waves like that against a female snake’s body, it pumps all the air out of her lungs and stops her from taking a breath. As she starts to run out of oxygen, she gets stressed, just as she would if a predator were attacking her. So instinctively, she craps herself. That reaction might discourage some predators from eating her, but unfortunately, it does not repel the male. Instead, it opens her cloaca and he takes advantage by inserting his forked penis.

As horrible as the sex lives of garter snakes and northern pintails
may be, they have nothing on bedbugs. Bedbugs are those parasitic insects that bite you when you’re sleeping. They used to be something you only had to worry about in dingy hotels (à la Henry Miller’s
Tropic of Cancer
), but in the past decade or so their populations have skyrocketed around the world, and today you can even pick them up in five-star hotels. The reason for their resurgence is unknown, but it’s quite alarming. Bedbugs feed on human blood, but however disturbing their feeding habits may be, those don’t hold a candle to how gross their mating behavior is. Bedbugs are
nasty
.
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Bedbugs are tiny, and they hide most of the time in walls, electrical sockets, piles of clothes, or pretty much anywhere in a bedroom. About once a week, a female bedbug comes out of her hiding place, crawls into bed with a human, bites the person, feeds for twenty to thirty minutes, and then crawls back to her hiding place. As she heads back across the room to hide, she’s well fed and therefore at her most fertile. So, on her way back she is approached by several males.

This is when things get ugly.

Bedbugs have a bizarre form of mating called traumatic insemination, in which the male pierces the body wall of the female with his penis and injects his sperm into her body cavity. She has a hole, through which she lays eggs, but he doesn’t put his penis in there. Oh no—instead, he just stabs her in the middle of her body and makes a new hole. This obviously damages the female, reducing her lifespan about 30 percent below that of a virgin female. Too much mating can even kill her.

Now, a female needs to mate in order to pass on her genes, and traumatic insemination is the only ticket to pregnancy, so mating is helpful to her, even if she does get stabbed in the process.
Her problem, though, is that it doesn’t just happen once. On her journey from the human’s bed to her hiding place in the wall, she will typically receive traumatic inseminations from five or so different males. One mating would give her more than enough sperm to fertilize all her eggs, but five traumatic inseminations give her twenty to twenty-five times more than she needs, and each one of those matings further reduces her lifespan. For a female, it’s a bad situation.

Males don’t care about that, though. To a male, all that matters is that
his
sperm are the ones that fertilize her eggs, and as a general rule, the last male to mate with the female gets to be the father of about 68 percent of the offspring. So even if she has mated with four other males today, and even if another mating will push her ever closer to the brink of death, there’s a huge incentive for a new male to be the fifth.

For her part, the female can’t really do very much about the traumatic inseminations themselves. Instead, females have evolved an organ called a spermalege to help them deal with the aftermath. Mostly it brings immune cells to the stab wound to make sure the fungi and bacteria all over a male’s penis don’t infect her body, but the spermalege also has a role in moving the sperm to the part of her body where the eggs are. Traumatic insemination by multiple males clearly isn’t optimal for her, but her body does what it can to deal with the brutal reality of life as a bedbug.