Surviving the Extremes: A Doctor's Journey to the Limits of Human Endurance (10 page)

Antonio pointed to a log alongside the path. It looked as if it would make a good bench for a tired doctor, but I had been in the jungle long enough to know that fallen trees were not for sitting. Peering closer, I saw the bark had sprouted hundreds of pastel-colored mushrooms. Many of them were no doubt edible, but over, around,
and between them, in constant motion, were thousands of 2-inch-long, shiny black ants.

“Conga”
Antonio told me.
“Mucho dolore, mucho fiebre.”

I could believe it. Conga ants are ill-tempered insects with venomous stings very similar to wasps. Both carry their poison in their abdomens, which have pointed ends for stabbing. In fact, the two species are very closely related, with the same basic body design, except that somewhere along the way ants lost their wings, making them the foot soldiers while the wasps remained in the air force.

Antonio pointed out another ant that was smaller and less aggressive-looking than the conga. I didn’t know the name but I recognized it. Indians crush it and then inhale the vapors to cure colds. I made a motion of grinding my thumb into my palm, then closing my fingers loosely around my nose. I wanted Antonio to know I remembered what he had taught me.

There was a neat black stripe across the path ahead of us, and as I got close I saw that it was alive with movement. Thousands of ants were crossing the trail in both directions. With the thick underbrush on both sides I couldn’t tell where they were coming from or where they were going, but I knew what they were: army ants, the terror of the tropics. Army ants congregate in colonies of millions and are the only ants without permanent homes—they are too destructive to linger long in any one place. Every month or so, the queen lays a quarter-million eggs. With that many mouths to feed, the ants go on a rampage, dividing up into highly organized columns, each containing hundreds of thousands of soldiers searching for food. Army ants are carnivores. They’ll kill anything in their path, from insects to crocodiles, then carry it back to their queen in bite-sized pieces.

Like all ants, in the tropics and elsewhere, army ants flourish only because they’ve formed a highly organized society. One ant would be powerless to affect its environment and unable to survive outside its protective “civilization.” Humans have flourished in the same way. Pitifully weak and slow, we have increased to enormous numbers thanks to our ability to form societies. Without that “artificial” protection, how many of us would survive?

But the protection of numbers is not truly artificial; it’s a natural extension of the will to survive. One can imagine that single-cell organisms, capable of living on their own, started to stick together in pairs, and then in groups, to give themselves an advantage over their enemies and competitors. Each of the cells gradually specialized its design to allow the whole unit to function more effectively. The grouping of cells became what we see now as a “body”—a collection of highly specialized cells working together and wholly dependent on each other’s proper functioning for survival.

Human society is like an even larger organism—the next step up. The individual parts may not physically adhere, but the society operates as one animal, competing with other societies for survival through war, economics, and culture. As is true with organ systems within a body, society functions best when roles are well defined and executed efficiently.

This particular society was on the move, but apparently not marauding; so we bent over to examine it. Both flanks were guarded by lines of larger ants with large white heads and pincerlike jaws that looked like ice tongs. On their tails were venom-filled stingers. These were soldier ants, the fierce warriors who lead the attacks. I had learned about the ants from two of our expedition entomologists who were studying them at Zancudo Cocha, and I had already seen many soldier ants up close in jars around the camp. There they were biological specimens. Here in the wild, they were formidable enemies, unnerving to see in such great numbers.

Though I knew a lot about the ants’ destructive power, I didn’t appreciate their medical value. That was about to change. Antonio focused in on one of the soldier ants, following its movement for a few seconds, his pinched thumb and index finger hovering above it. Then he flicked his wrist and very neatly picked it up, holding it between its pincers and its stinger. He showed me the ant and then his finger, unbandaged, which he had cut earlier that morning on the sawgrass. He turned the squirming ant upside down and stuck its head against the wound. The ant instinctively snapped its jaws shut, pinching the skin edges together. Antonio then twisted the ant, snapping off its
body and leaving the head embedded like a staple. Three ants were enough to close the wound.

We turned our attention back to the trail. Closer to the river, the route became more heavily traveled by animals using it as a highway to the water. Not that I saw any—an animal could be one tree away and I wouldn’t have seen it.

Lying low and blending in are essentials for animals of prey. But one animal breaks the rule spectacularly, for its survival depends on being noticed. They make themselves so obvious that even I was picking them out, though none was longer than 2 inches. Their colors were dazzling, with striking contrasts—one a brilliant blue, another red with yellow stripes, another black with a bright red head, still another orange swirled. They hopped about in broad daylight, as if to say, “I dare you to eat me.” They were poison-dart frogs, the worst meal anyone can ever have. Biting into one releases a powerfully bitter taste, followed immediately by numbness in the face and burning pain throughout the body. Spitting the frog out might or might not spare the predator’s life. For the reckless animal or human that tastes one, the meal proves an unforgettable experience, if not a terminal event.

The frog’s poison is produced by sweat glands on its back and exists purely for defensive purposes—the frog has no way to inject it. Like ordinary sweat, it is released when the frog is scared, or bitten into. The toxic brew evolved as a germicide to cleanse the frog’s delicate skin, which, always being moist, provides an ideal growth surface for bacteria and fungi. The skin contains neurotransmitters, chemicals that naturally occur in nerves—but in concentrations thousands of times stronger than normal. When it comes in contact with an animal, the poison floods its nervous system, shorting out circuits and causing paralysis of nerves and muscles. Some frogs produce a brew so effective it can kill a human who simply touches its back.

The poison frog won’t benefit much if it has to be eaten to kill its predator. In this defensive strategy, an individual sacrifices itself to ensure survival of its species. The postmortem revenge of each frog quickly teaches a lesson to any would-be predator to stay away from
the frog’s relatives and descendants. Had the frog made the sacrifice voluntarily and with awareness of what it was doing, as sometimes occurs in higher species, it would be called altruism.

Altruism has such an immediately negative impact on the individual that it might seem natural selection should have eliminated it long ago. Yet altruism is common among organized societies from army ant colonies to human civilizations. The reason is that the drive to survive comes not from the individual animal but from its genes. Genes are interested in preserving themselves, but so long as there are lots of copies spread throughout a species, the loss of a few is insignificant. If an animal’s sacrifice protects the other repositories of its genes, that would be fine from the genes’ perspective; they come out ahead. The closer the sacrificing animal’s genes are to the animal it is sacrificing itself for, the more effectively the system works; and in fact, the impulse for altruism is strongest for the immediate family, then progressively weaker for other relatives, others of the same ethnic group, and others of the same species.

The system has worked well for the small poison-dart frog. Antonio, like other Amazon predators, eats only large frogs, and even then only after removing the skin. He said he saves the small beautifully colored ones he catches to make poison-tipped darts for his blowgun. Though so far I hadn’t seen one, I knew I was in blowgun territory. A blowgun is a hollow bamboo tube with a splinter of wood placed inside one end. A sharp blast of air propels the splinter out the other end like a rocket. The blowgun is made entirely from local ingredients, but I thought it might now be obsolete. I told Antonio I was surprised he still used one.

“I like hunting that way,” he replied. “Though using a shotgun is easier.”

The trail seemed to come to an abrupt dead end. Ahead of us was a wall of small plants and bushes, as well as an overturned tree whose base was taller than I was. The tree had fallen recently, leaving a hole in the canopy, but already the sunlight that penetrated through that hole had stimulated enough new growth to obliterate the trail. We worked our way around it, stepping over some branches and limboing under some others, moving through a “no-touch” forest. I couldn’t
place my hands anywhere for balance—leaves have itchy coatings, branches have thorns, and barks have biting ants. I was constantly afraid to anger some insect, make a snake think it was under attack, or inadvertently grab a poison-dart frog.

The temperature and humidity had been rising steadily; breathing in was like inhaling the exhaust from a Laundromat. I wasn’t tired, but I was sweating. My shirt couldn’t have been wetter had I swam here. Antonio must have thought I needed a drink and a snack. He eyed a thin bamboolike canawaska vine and tapped it with his machete. Deciding he liked the sound, he chopped out a section that included two knots. He tucked it under his arm as we went on a little farther. In a small clearing, we stopped for a break but I didn’t sit down. I noticed Antonio remained standing as well. The canawaska section was a hollow tube sealed at both ends by the knots. Antonio cut into one end and a clear liquid ran out. He offered it to me first, but when I hesitated he took a drink himself. I soon followed. It was fresh-tasting water.

While I drank from the canteen he had made, he stepped off the trail and, with three or four strokes, hacked down a 60-foot palm tree roughly 2 feet in diameter. He chopped out a section of the trunk near the top and split it open. He took out the center and then split that open. Inside were little white shoots. He peeled them and gave me some. They were hearts of palm.

Antonio was an opportunistic hunter. He spotted a tree with lemony-looking fruits just beginning to ripen. With a stick, he beat the branches until a good one fell, then he cut it up and shared it with me. Antonio really enjoyed it, and went back for a second one. The fruit had a lot of uses, he informed me—as a tea it brought down fevers, and the women used it as a contraceptive. It was a sweet-tasting dessert, but it had a lot of pits. I spit mine out; Antonio put his in his pouch.

He was completely at ease and relaxed here. The jungle was Antonio’s home. Although he didn’t have much speed or strength by animal standards, he had knowledge; and knowledge was enough to provide him with a comfortable life.

Lunch over, Antonio nimbly and quickly wove a basket out of
leaves and vines and placed it in the clearing. As we left, it started to rain—a real downpour from the sound of it, but I wasn’t getting wet. Only after the tightly woven canopy was fully saturated did some of the rain start to drip through. As we neared the end of the trail, animal signs were becoming more obvious, at least once Antonio pointed them out. There were capybara tracks, peccary droppings, and even bark scratched by a jaguar. Antonio spotted an agouti, a rodent that resembles a big, tailless squirrel. As I turned to look, a raindrop washed some bug lotion into my eye. By the time I rubbed it out, the agouti was gone. I could, however, see some light through the trees. Though the leaves continued to drip, the rain had stopped and we were approaching a large clearing. The sun was out, and just ahead now there was a wide patch of blue sky. The green corridor ended. I stepped outside.

The village didn’t have a name. It was a grouping of five huts—probably a collection of related families. The dirt around the huts was smooth and cleared of all vegetation except for occasional patches of bright red flowers. Two women were sitting on the ground and skimming their machetes over the dirt, removing any irregular clumps as if preparing a clay court for a tennis match. Behind the huts were rows of banana trees and cornstalks that blended into the jungle. Children were playing with or chasing a menagerie of pigs, dogs, and chickens. There are many such settlements scattered across the Amazon. I wondered if there were any in which the Indians didn’t wear T-shirts.

Each neat, square wooden hut was built on a platform raised up on stilts. Chonta-wood poles at each corner supported a roof of thatched palm. Part of the platform had no walls, making it a porch, while the rest had walls of split bamboo rising only halfway up so that it was unnecessary to have windows for ventilation or light or to see an approaching stranger.

One was approaching now. The dogs barked and the children stopped playing, staring at me as if I were a zoo specimen. Antonio
and I crossed under a rope strung between two huts on which laundry was drying and stopped at the base of the next hut. A pig was lying in the shade against one of the stilts. It had a festering sore in its side and four baby chicks sitting on its flank. As Antonio announced our arrival, I watched the chicks peck at the pig and eat off its fleas.

To get into the hut, we climbed up a thick log with sawtooth steps cut into it that was inclined against the porch. In the semidarkness within, a girl was sitting on the floor. I recognized her as the one who had listened carefully to the instructions I had given Berullio about his son, her brother. She smiled and offered us seats on tree trunk stools. While she spoke with Antonio, a four-year-old girl was feeding noodles to a two-year-old, and I glimpsed a boy balancing himself on the roof in order to add thatch. We were in the front or “guest” section of the hut, separated from the private living quarters by a bamboo wall. From behind that wall came an elderly woman holding a decorated clay bowl filled with a milky liquid. This was
chicha,
a traditional alcoholic welcoming drink made from manioc, a potatolike root vegetable that grows practically everywhere in this part of the world. I took a polite sip; it tasted like sour yogurt. The woman then took a drink herself, but instead of swallowing it, she spit it back into the bowl.
Chicha
is prepared by chewing the manioc to mash it up while adding spit to speed the fermentation. The woman did this continuously as we sat. I declined her offer of a second drink, though I convinced myself that the alcoholic content would kill the bacteria in the bowl and that my health risk was less than it would have been had I kissed the old woman on the lips.