Mother Nature Is Trying to Kill You (20 page)

To me, this story is an especially good reminder that nature
isn’t a model for what humans should do. Somewhere in a mountain pond in Spain, a male frog is squeezing eggs out of a female that was killed by gangs of aggressive, copulating males. Next time someone uses nature as a justification for any decision they’ve made, like what a woman’s role should be in the home, perhaps, just ask them how
Rhinella
fits into their nature-inspired world.

In those instances where sneaker males mate with living females, the sex has to happen relatively quickly, or else the dominant male will have time to come over and beat the sneaker up. Marine iguanas, found only on the Galápagos Islands, are another species in which sneaker males operate, and they’ve found a handy way to speed things up.
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Female marine iguanas will mate only over a few short weeks each year, and the fierce competition among males has large males defending large territories then, for access to females. You might not know that a male marine iguana needs about three minutes of sex to achieve orgasm (though that’s a great conversation starter at parties, in my experience; you’re welcome). For a large male, that’s no issue, but smaller, sneaker males don’t have that kind of time. Anytime a sneaker male manages to have sex with a female, there’s a very good chance the dominant male will come break things up before he can transfer his sperm, thus making his sneaker strategy useless.

Here’s how sneaker male marine iguanas deal with that problem. When a sneaker male sees a female walking by, he gets into a sex position, with a bent body and tail, just as he would if he were having sex with her. This apparently is how iguanas masturbate, because it causes a few drops of semen to come out of his penis. That semen dries on the tip of his penis, and
when he eventually does have sex, that old semen gets deposited inside the female. He’ll get even more sperm inside her if he manages to stay on top of her for the full three minutes required to have an orgasm, but just in case he gets pushed away by the dominant male before that happens, some of the dried semen he produced during masturbation will be left inside her. And that’s better than nothing.

Even teeny-tiny animals use sneaker male strategies. If you ever go snorkeling on a moonless night in the Caribbean, you may luck into seeing blue pulses of light shooting up through the water in complex patterns from the sea grass below. I’ve never seen this myself, but it’s on my life list to see someday. Big-time.

Those light pulses come from special light-producing organs on shrimplike creatures called ostracods.
²¹
The males are tiny, less than two millimeters long, and they make those light displays to attract females. Over the course of about twelve seconds, a male flashes ten to twenty times, swimming upward through about two feet of water, leaving little blue glowing dots behind. Males make these displays in huge numbers, and I imagine they are breathtaking. Female ostracods certainly think so. A female impressed by a male will approach in darkness, then grasp the male of her choice. They have intercourse, and he places a sperm packet inside her body, before she swims off to go brood her eggs.

The problem with those displays is that they also attract predators. Lighting up and then moving in a very predictable pattern is a great way to end up in a predator’s stomach, but the male ostracod really has no choice if he wants to mate.

Well, actually, there is one other option. Since a male moves in a predictable pattern, a sneaker male can position himself immediately above another male and then swim just ahead while the
performer makes his display. With any luck, the sneaker male can intercept an approaching female, and she’ll mate with him instead of the male who did all the work. What’s different about ostracod sneaker males, compared to just about any other kind of sneaker male, is that males switch back and forth between the two mating strategies as much as they want over the course of a night. Unlike frogs and iguanas that have their roles dictated by their body sizes, ostracods seem to have a little more flexibility and to know how to use it. The ostracod embodies for me the mind-boggling wonder of the natural world. Here you have a tiny animal doing secret light-emitting dances in the night, with a mating ritual as complex as that of any bird or mammal, even though it’s smaller than the head of a pin. The world is full of surprises, and the more you learn about any particular group of animals, the more surprising it becomes.

Another ocean-dwelling sneaker male that makes me smile every time I think of it is the giant Australian cuttlefish. It’s an eight-legged cousin of the octopus, up to twenty inches long, weighing in excess of twenty pounds. Cuttlefish are well-known for their ability to instantly change color, which allows them to camouflage when they need to, make flashy displays to scare off predators, or communicate with other cuttlefish. And of course, if you can communicate, you can lie. Sneaker male cuttlefish are fantastic liars.

Male cuttlefish aggressively defend females, but the females aren’t crazy about commitment. There are lots of males to choose from, and even though she rejects 70 percent of mating attempts, she still has sex up to seventeen times each day. About 65 percent of the time, that’s with a large, dominant male. But a smaller male has three strategies for meeting females. Sometimes he’ll
approach a female out in the open, right in front of the dominant male (but he has to hurry); sometimes he’ll approach a female under a rock, out of sight of the big male; and sometimes he’ll use a third strategy—dressing in drag.
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You can tell a female cuttlefish from a male cuttlefish by the shape of her fourth pair of arms and by her mottled skin patterns. So “cross-dressing” sneaker males tuck their fourth arms underneath their bodies, change their body colors to look like a female, and then take on the same body posture a female takes when she’s about to lay eggs. Females about to lay eggs aren’t usually receptive to mating advances, so that body posture keeps most other males from trying to mate with the disguised cuttlefish.
^V

Pretending to be a female is a sneaker strategy that can pay off. Disguised, a sneaker male can often sidle right up alongside a true female, even while she’s being guarded by a large, aggressive male. When the sneaker male makes his move toward the female, sometimes she rejects him, sometimes he gets chased off by the dominant male, but quite often, mating goes just fine.

Another male who pretends to be female is the red-cheeked salamander of the southeastern United States. When red-cheeked salamanders mate, a male and female come together and perform ritualized movements, crawling over one another and rubbing their bodies against one another in very specific ways. Being amphibians, like frogs are, male salamanders don’t have penises, so during mating he glues a ball of sperm to the ground. As they move together, the female slides her body over the sperm ball and draws it up into her body.

If a male red-cheeked salamander comes across a male and female in the middle of a dance, he will sometimes push them apart. Other times, though, he will sneak in between them and then continue the dance as though he were the female. The original male presumably doesn’t realize there’s been a swap, so the dance continues until he deposits his sperm packet. Then the false female turns around and bites him, causing him to run away.
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To me, sneaker males embody envy even better than thieving predators do. When smaller males within a species bump heads with larger males, little guys usually end up holding the short end of the stick. Whether or not he’s
literally
envious is a question that might someday be answered by clever experiments, but since this happens in so many kinds of animals, we can never possibly know for all of them. Whether or not it’s envy, those smaller males seem motivated to make the most of what they’ve got to get their genes passed into the next generation. In nature, the game’s not necessarily over for a male who gets sand kicked in his face.

Now, this is exactly the kind of moment when we’re tempted to look at these animals and say something about what they can teach us. We may want to point to Bill Gates and Mark Zuckerberg as nerds who came out ahead in the game of life, but that’s a dangerous, slippery slope. Let’s say you look at alternative mating strategies in male animals and then say something to a teenage boy like “Listen, even if you’re not on the football team, you’ll eventually meet a woman who loves you for who you are, who sees your sweetness, your intelligence, or your sense of humor.” That’s a lovely thing to say, but that’s not what’s happening out there. You’re not asking the teenager to intercept a female on her way to a date with the football player and force her to copulate with him.
You wouldn’t tell that male teenager to sneak into a couple’s bed while they’ve having sex and take the role of the female so that the football player will ejaculate in the wrong place. You can’t pretend nature’s an instruction manual. It’s fine to take inspiration from nature, but you still have to have common sense. Humans should abide by morals, and nature is not a place of morality. The fact that something happens in nature can never be used to justify it in human behavior, no matter how harmless it might seem to do so.

When my first real girlfriend and I broke up in high school, she sent me a note (this was before text messages) that said “Tell me, Dan. Is ignorance really bliss?” To this day I still have no idea what she was talking about (maybe that was her point), but for some reason, that concept has haunted me ever since. If ignorance is bliss, then
could gaining knowledge make you sadder?
If you spend your life seeking new information, is it possible that some joy might be lost?

As a parent, I’m starting to think so.

Learning about the natural world has made my life richer than it would otherwise be, but I know that learning about evolution has also peeled away some fairy tales that might have made things a little easier. I imagine that a certain bliss might have come from the belief that my great-aunt Claire could look down from heaven on the birth of Sam and smile along with me at the family resemblance. It might also have been helpful to believe in those tense moments before Sam’s first breath that some benign natural force was looking after him. But the time I’ve spent learning about science has led me not to believe those stories.

In those instances, maybe it’s possible that my science-based perspective has robbed me of a little happiness, but I decided long ago to keep my experience of the world rooted as firmly in reality as possible. That said, though, I can’t help wondering what it would be like just to love Sam without that background conversation about meat robots playing in my head. It’s almost enough to make me envious of those parents who don’t think about evolution at all.

Almost.

I
. A doula is a nonmedical person who assists before, during, and after labor and childbirth, acting as an experienced resource for the family. To me, the biggest benefit of having a doula was just having someone there the whole time saying, “This is normal.”

II
. Claire Riskin was my father’s father’s sister. Roughly one-sixteenth of Sam’s DNA is the same as hers.

III
. Theft is really a type of parasitism, since (as you’ll remember from two chapters ago) parasitism describes any relationship between two organisms in which one gets a benefit (the parasite) and the other pays a cost (the host). In the case of parasitism by theft, biologists use the word
kleptoparasitism,
and talk about animals that are kleptoparasites of other animals. You might recognize the prefix
klepto-
from the word
kleptomania,
the disorder that causes people to steal pathologically.

IV
. This frog mating cuddle is called
amplexus,
which is Latin for “embrace.”

V
. That said, though, the disguised male still frequently gets hit on by other males (some of whom, confusingly, are also disguised as females: it’s like an elaborate Shakespearean play out there).