Songs of the Dead (13 page)

Now, you may wake up that morning, and you may have no idea that these pinworms are living inside of you—I mean, how many other creatures live in or on our bodies about whom we know next to nothing?—but here is what you will know: your anus itches. What do you do when your skin itches? You scratch it. If you use your finger to scratch your anus—and I know you're far too sophisticated and health-conscious to do this (and besides, it would be just plain gross), but if you're like me you weren't quite so sophisticated when you were an infant or a young child, but merely knew that when something itched you scratched it with your scratcher—you get infectious eggs on your finger. If you happen to put your finger in your mouth, the eggs are home free. If you happen to touch clothing, kitchen counters, schoolroom desks, the eggs can come to rest there, waiting for someone else to touch that particular cloth, counter, or desk, then put a finger to a mouth.

The question I'm asking right now is this: when a child scratches her itching anus, who is in charge? The pinworm is changing the child's behavior.

Not only that, but if the pinworm changes the child's behavior, is the pinworm now a part of the child? At what point does someone else become a part of you? Is the flora and fauna in your gut part of you? How about the cells of your brain? How about the infection that—who?—makes you sneeze so you can expel aerosols to be picked up by some other host? “I need to sneeze.” Who needs to sneeze? You or the infection?

Who is an invader, who is a hitchhiker, and who is a part of you?

But of course, just because someone changes your behavior doesn't mean they're a part of you—otherwise Mrs. Purcell, my fourth grade teacher, would have become a part of me by holding me in during recess. I can change our dogs' behavior by giving them treats, and they can change ours by begging. So there's obviously more to the question of who is part of you than simply affecting your behavior, just as there is more to the question than simply being inside your skin.

I got a pretty bad prostate infection last year. In retrospect, the earliest symptom was that I wanted to have lots of orgasms. Allison was gone, first for a long visit to her parents, and then to oversee the hanging of her works at a gallery in San Francisco, so I was masturbating a lot. I mean a lot. My historical average when I'm on my own is probably three times a week. I was masturbating three or four times a day, not stopping till long after the muscles in my forearm started to burn. I tried switching to my other hand, but that never seemed to work: not only was my right hand out of practice but I felt as though I were cheating on my left. And I knew there was no way I could keep one hand from knowing what the other was doing.

At this point I didn't know I had an infection: I thought it was a temporary obsession. A couple of weeks later, I started to feel pain in the tip of my penis. My first thought was that I had somehow hurt myself. The pain was sharp—not like a strained muscle, but I didn't know what else it could be. Maybe some lubricant or stray bit of fabric had worked its way into my urethra and festered. I was at a loss. The pain kept getting worse. Finally I went to a doctor who, with no tests, insisted I had Chlamydia. Never mind that neither Allison nor I had been with anyone else since well before we met. I had myself tested: he was, after all, an authority figure. Negative. More tests. Negative. I went to a urologist who told me I had a prostate infection. He gave me a prescription for antibiotics, and he also—and here's the interesting part—gave me an informal prescription for orgasms.

He did this because it's very difficult to clear infections from the prostate. The prostate's weak blood supply combines with its shape—it has lots of long skinny tubes that lead to reservoirs of seminal fluid—to render antibiotics relatively ineffective: the antibiotics can't get into these reservoirs. This means that if you don't drain the reservoirs, they become safe havens for the infection. Thus the doctor's orders. Allison was home by then, and very pleased with the prescription.

Now here, for me, is where it gets exciting. I had started compulsively masturbating a couple of weeks before I had any other symptoms, and a couple of months before I got diagnosed. Even had I known I had a prostate infection, the healing properties of ejaculation wouldn't have occurred to me: I'm embarrassed to admit that although I'd been ejaculating for years, I'd been ignorant of how it all works, with no idea the prostate was even involved. But my prostate knew it was infected, and it knew it had to be drained. What I thought was a strange and sudden obsession on my part was instead one part of my body attempting to rid itself of an infection. I asked before, “When you need to sneeze, who needs to sneeze?” I ask now again: Who's in charge?

I asked the urologist why a prostate infection didn't hurt in my prostate, but rather at the tip of my penis (and by then all along its length). He said nerves run past the prostate down the penis. At first this made no sense to me: it would be like pulling my hamstring but feeling the pain in my ankle. I went home and thought about it, and suddenly I understood. If the prostate needs to be stimulated in order for me to ejaculate, and if part of the purpose—at least reproductive purpose—of sexuality is ejaculation, then if the nerves extended no farther than the prostate, sex would be an entirely different and rather more complicated affair (and I don't even want to think about what masturbation would be like from the perspective of a non-contortionist). In order for me to ejaculate, I or someone else would have to stimulate my prostate directly. While this can be done, it's far more handy, if you will, to be able to stimulate the prostate externally. I think I'm stimulating my penis, and in a sense I am, but the real action happens elsewhere, in my prostate, as the prostate is stimulated almost by proxy.

It sometimes seems that every time I learn something new, I become existentially more confused. Not only am I sometimes unclear as to who is in charge—when I do something, who is this action serving?—but now, when I feel something, I begin to wonder whether what I am feeling is what I am feeling. I wonder if where I am feeling it is where I am feeling it. Indeed, I sometimes even begin to wonder if when I feel something there might be others, too, who feel what I feel, only they feel it, like the prostate, by proxy.

Lately I've been thinking about
Dicrocoelium dendriticum
, the lancet liver fluke. It's a parasite with three hosts. The first is a snail, who, in the normal process of eating sheep or cow shit, accidentally eats lancet liver fluke eggs. The eggs hatch, develop into sporocysts and then into cercariae (stages of parasite larval development), then emerge from the snail coated in slime. The second host is an ant, who in the normal process of eating snail slime also eats the larval flukes. The larvae continue their development in the ant's gut, then chew their way out through the ant's exoskeleton. Because the flukes don't yet want the ant dead, once they're out, they patch up the holes in the ant and cling to the ant's outside. That is, all but one of them cling there. One fluke is chosen instead to chew into the ant's brain, where it actually takes over the ant's movement and control of the ant's mandibles. Come sundown, this fluke guides—convinces?—the ant to climb to the top of a piece of grass and to bite down hard, then cling there, waiting for the third host, a sheep or cow. If no ungulate shows up that night, the ant climbs down in the morning to resume its normal life, until the next night, when the fluke once again takes the reins and sends the ant back up a blade of grass. When an ungulate eats the grass to which the ant is clinging, it accidentally eats the ant, and therefore all the liver flukes. The flukes—eventually there can be as many as 50,000 in a mature sheep—make their way to the cow's or sheep's liver by way of the bile ducts, and within a few months begin laying eggs of their own. The eggs are deposited on the ground in the creature's feces, where they are eaten by snails and the story starts all over.

By now you can probably guess the question that I ask as the ant climbs to the top of the grass: who's in charge here?

I've also been thinking about horsehair worms, nematode-like creatures whose name derives from the old belief that they generate from horsehairs that fall into water. They do look kind of like horsehairs, long and slender, and they often do live in water.

Their story begins with eggs laid in water or on damp soil. The eggs hatch, and the young worms enter the body of an insect such as a beetle, cockroach, cricket, or grasshopper, either by being eaten or by simply penetrating the insect's body. For weeks or months the worm develops inside the insect it is slowly killing, until it can often be many times longer than the host in whom it resides. By the end, the worm occupies almost the entire body cavity of the insect except for the head and legs. But the worm has a problem: if the host dies away from water, the worm will die with it. So what does it do? As it nears the end of this stage of its life, the worm drives the insect away from its home, and when it reaches water the worm causes the insect to jump in, where the worm can emerge, killing the host as it does so. Researchers have found that if you remove a host cricket, for example, from the edge of a pond, it will return and keep returning, until either it is dead or the worm has made its way into the water.

Once again, as the cricket walks slowly toward a pond, what is it thinking? Who's in charge?

And now I'm thinking about a certain solitary wasp. I'm not sure if you know this—I didn't until my mid-twenties—but many species of wasps are not social creatures, but rather live alone. Further, many wasps hunt only one prey species. For example, a particular species of wasp may rely only on a particular species of spider. Typically the wasp paralyzes the spider with a sting, carries the spider to a nest she has prepared, lays an egg on the spider, then closes the nest. The egg hatches and the young wasp consumes the still-paralyzed spider (paralyzed, instead of killed, to keep the flesh from spoiling).

But the wasp I'm thinking of takes things one step further. Instead of preparing the nest for her offspring, she gets the spider to do it for her. It all starts, as it does with these wasps, with a paralyzing sting, in this case on the mouth. The wasp then lays a single egg on the spider's abdomen.

This time, however, the paralysis is not final. The spider soon recovers and goes back to her life of spinning, weaving, waiting, eating. But now a wasp larva clings to her belly, making holes in her abdomen through which she can suck the spider's haemolymph (blood). She injects the spider with an anticoagulant to keep the food flowing. This is how life goes on until the wasp is ready to kill the spider. On the evening of the last day of the spider's life, the larva injects the spider with another substance. Soon the spider begins to spin a new web, a web that is different from anything she has ever built before, a web strong and durable enough to hold the wasp larva as she pupates. When around midnight the spider finishes this task, the larva injects the spider with yet another substance, one that kills the spider outright. The larva feasts until mid-day, then drops the spider's body to the ground and waits in the web until evening. She spins her cocoon, where she will turn into an adult.

If you remove the larva from the spider after she has injected the spider, but before the web is constructed, the spider will continue to spin this special web, and spin it again, and again, for several days, until the spell of the larva has worn off, and the spider can go back to as she was before.

It's not just these particular flukes, horsehair worms, and wasp larvae who influence or control the behavior of others. There are flukes and tapeworms who make fish swim near the surface of the water, so the fish—and thus the flukes or tapeworms— can be eaten by birds. There are barnacles who take over the bodies of crabs, make the crabs incapable of reproducing, and get the crabs to take care of the barnacles' offspring. There are worms who move into the bodies of snails, reproduce, and whose larvae move into the snails' eyestalks, where they glow in neon colors as the normally reclusive snails move into the open, where they can be easy prey for the birds, who are the worms' next host.

And of course there is the single-celled parasite
Toxo-
plasma gondii
. These creatures normally cycle back and forth between rats and cats, as rats eat infected cat feces, and cats eat infected rats. The parasite doesn't seem to deeply affect cat behavior— after all, the cat merely has to shit to pass on the parasite, and anyone who has ever kept company with cats knows that they already excel at this—but it does affect the behavior of rats. This single-celled creature causes infected rats to become less timid, more active, and to have a greater propensity toward exploring novel stimuli in their environment. Infected rats also lose their instinctual fear of cats. I'm sure you can see how all of these changes make it easier for cats to catch rats, and thus to catch
Toxoplasma gondii
.

Cats and rats aren't the only creatures who harbor
Toxo-
plasma gondii
: they live inside humans too, who also can get them by ingesting infected rats, or far more likely, by ingesting infected cat feces, presumably accidentally through touching feces, then eventually touching fingers to mouth. You can also ingest them by eating undercooked pork, lamb, or venison. Most human carriers show no physical symptoms, but some people suffer severe damage to their brain, eyes, or other organs. Infants in the womb are especially susceptible to damage from infection, which is why pregnant women are cautioned to get someone else to clean the kitty litter. Toxoplasma gondii live inside 60 million Americans. Half the humans in England are hosts to these creatures, and 90 percent of the people in Germany and France.

It may surprise those who believe that humans are fundamentally different than all other animals to learn that rats aren't the only creatures whose behavior is changed by Toxoplasma gondii: the same is true for humans. Studies conducted at universities in Britain, the Czech Republic, and the United States revealed striking personality changes among some infected humans. Changes include an increased likelihood to develop schizophrenia or manic depression, and delayed reaction times that lead to greater risk, for example, of being involved in automobile crashes. There are more subtle changes, too. Infected men tend to become “more aggressive, scruffy, antisocial and . . . less attractive.” They are characterized by researchers as “less wellgroomed, undesirable loners” who are “more willing to fight” and “more likely to be suspicious and jealous.” Infected women become “less trustworthy, more desirable, fun-loving and possibly more promiscuous.” They spend more money on clothes, and are consistently rated as more attractive.