Surviving the Extremes: A Doctor's Journey to the Limits of Human Endurance (12 page)

In tribes like Antonio’s, when the boys reach puberty they are brought to a sacred waterfall for their rite of passage. They fast for three days, ingest ayahuasca and potions, listen to the constant din of the waterfall, and search the heavens for God. Antonio remembered seeing a sky filled with jaguar eyes, darting snakes, and virgins hiding behind clouds. They spoke to him and he replied, speaking words no one could understand. Only then was he deemed ready to return to the village to take up his role as an adult.

Antonio described the effects of ayahuasca as making him feel he was part of a larger organism, part of the earth; he no longer sensed any separateness from the world around him; his wants, his fears, his sense of time and of self all vanished. This didn’t sound like a chaotic reaction to circuit overload. What he was describing was a harmonious phenomenon, virtually identical to what has been reported throughout recorded history in many, many cultures, whether brought about by potions and rituals or by prayer and meditation. However different the means of creating it, the experience is universal, implying that it involves effects on the most fundamental structures of the brain and therefore reflects its innermost processes.

The brain is hardwired with circuits of incredible complexity but with particular stations responsible for specific functions. Outside threats are monitored by a primitive, deep-seated portion of the brain called the amygdala. When the amygdala is stimulated, we feel fear. Orientation to time and space is a more complex activity carried out by the parietal lobes at the top of the brain. The left lobe maintains an awareness of where the borders of the body are. This part of the brain is not well developed in the first year of life, which is why an infant, looking simultaneously at his hand and at a toy, cannot distinguish which object is himself. The brain’s right lobe assesses the space around the body. Together the two lobes form our navigational system. An injury to this part of the brain might result in an inability to calculate the maneuvers necessary to sit in a chair. Awareness of self
is centered at the front of the brain, in its most highly evolved portion, the frontal cortex, a processing center and the seat of attention, alertness, and concentration. Absent or rudimentary in almost all other animals, it takes years to develop, and until it does, humans have no concept of themselves as individuals.

For someone to lose his fear, his sense of time and place, and his self-consciousness, the brain circuits to the amygdala, parietal lobes, and frontal cortex must all be interrupted. The interrupter is the hippocampus—a primitive brain part that meters incoming signals and, like a circuit breaker, shuts down circuits temporarily when they get overloaded. Magic potions that recycle neurotransmitters to keep nerves firing; rituals that bombard the senses with pounding drums, gesticulating dancers, and endless incantations; ceremonies that generate fear with scary masks, animal sacrifices, or other acts of violence—all push the circuits into overload. Ritual participants deliberately exceed the capacity of the brain centers to handle the input from their environment. The hippocampus flips some switches off, maintaining circuits essential to life, such as breathing and heartbeat, but shutting down stimuli to the higher centers that are less important for immediate survival. With incoming signals blocked, the frontal cortex receives no stimulation and loses its awareness of the individual self. The parietal lobes, like any navigational system, cannot orient themselves without external time and location signals. The left side can’t determine any body limit, so it perceives itself as endless and intimately continuous with the rest of the world; the right side loses all outside reference points, creating a sense of eternal time and infinite space.

Prayer and meditation can have the same effect when the individual wills the frontal cortex to focus intensely and exclusively on one thought—God, or a mantra. All outside input is effectively blocked out just as if a switch were flipped, so the acolyte in quiet concentration can bring himself to the same state as the ritualist in frenetic activity.

Visions often occur during deep meditation, a phenomenon thought to be due to the internal quiet, which lowers the threshold needed to excite a nerve. Random bursts of impulses, similar to epileptic seizures, fire into various brain parts, including the temporal
lobes—the section of the brain beneath the temples that controls conceptual thinking and language and image associations. These bursts are more likely to occur when nerve cells are already irritated, as they are in epileptics, some of whom often experience auras or visions. These electrical bursts can also be triggered by fear, fatigue, low oxygen, and low blood sugar—all of them common conditions in survival situations. This may be how people in desperate circumstances see their loved ones before their eyes or hear God speak to them and suddenly find the motivation to survive.

Such explanations for spiritual transcendence hardly mean that religious experience is a trick of our brains. We don’t—and perhaps can’t—know from where the spark comes to excite the nerves.

Antonio wasn’t concerned with any of this, but his pharmaceutical knowledge was more sophisticated than even he realized. “Visions from ayahuasca alone are often dull,” he said matter-of-factly. “I like to add leaves from this one.” He pointed to a small green bush. It was a viridis, in the same family as the coffee plant, and known to contain tryptamine—a stimulant like caffeine. Tryptamines prolong the effects of serotonin, which ensures that viridis goes well with ayahuasca. Botanists have a great deal of difficulty distinguishing many of its subspecies, but it was no problem for Antonio. He pointed out two different varieties and said, “This one brings out red in the visions and that one brings out yellow.”

Tryptamines work when taken in combination with other ingredients but are inactive when taken by themselves orally. The Indians, without understanding the means by which these potions work (at least by our standards—they have their own explanations), have gotten around this problem in their preparation and use of another tryptamine-containing vine, the Virola, a member of the nutmeg family. The bark must be stripped from the bottom of the tree early in the morning before the sunlight strikes it and, presumably, heats up the resin, denaturing the tryptamine it contains. The resin is boiled and then dried, resulting in concentrated tryptamine. Pulverized and then snorted through a hollow bird bone, it is absorbed like cocaine, directly through the nasal membranes, bypassing the digestive enzymes that would interfere with the spirit communion the Indians seek.

Sophisticated agronomy was at work in the village garden, for both practical and spiritual reasons. The Indians planted chonta palms to supply thatching material for their huts, but the leaves grow high up and the thorny trunks are unclimbable. An easy-to-climb tree was always planted close to a chonta palm so that there would be convenient access to the valuable leaves. Also for convenience, villagers rooted certain hard-to-grow medicinal plants in gouges cut into the bark of other trees—a simple but effective form of grafting.

Other ecological considerations were more subtle and complex. Trees will tell you when new seeds need to be planted, Antonio told me, but only if you listen carefully. Certain types of bushes will grow well if they are planted together. That sounded like symbiosis to me: plants with complementary mineral requirements sharing the same soil. Antonio had a different reason. “It is because their spirits are
simpatico.”
No scientist would be rash enough to think he or she understands all the sources of energy in the universe; in the jungle, Antonio’s explanation seemed at least as good as mine.

Antonio was a teacher in the purest sense. It was a privilege to be in the forest with him. He was about sixty-five years old and had lived his whole life here. The knowledge of countless generations had passed to him from a tribe with no written language. Precious lore exists only in his memory and in the memories of those like him. When they are gone, the knowledge will go with them.

“Are any of your children going to be doctors?” he asked me, quite unexpectedly. The animation in his face was gone. Still holding the last plant we had talked about, he added, “My children and my grandchildren are not interested in plants. They want chain saws and outboard motors for their canoes.”

Antonio led me back to the hut. We would have to leave soon if we were to return safely to camp before dark. It would be a long trip, and Antonio wanted me to eat something before we left. In my honor they were preparing a special meal—a freshly killed paca, a large rodent, which was just then being held over the fire to singe off its hairs. The fire rose from a large metal box resting on logs in the front section
of the hut. Once the hairs were burned off, the creature was dropped whole into a pot of boiling water.

Antonio emerged from the back of the hut, carrying a small Tupperware container that had several holes punched in the top. He opened it slightly. Inside was a beautiful poison-dart frog, blue with black spots. Antonio showed me some darts as well. He explained that a dart is made from a bamboo shard, which breaks off like a big splinter. The shaft is smoothed; fuzz from kapok seed fibers is stuck on the back end to serve as a feather. He pointed to a notch just beneath the tip that creates a weak point. “When a person tries to pull it out,” he said, “the tip breaks off inside, giving the poison a chance to work longer.”

The frog poison is applied directly by holding down the frog with a bunch of leaves and poking it with the dart. A white, frothy sweat forms on the frog’s back and the dart tips are rolled in it. Various curare blends get added later. The poison remains active for a year. One frog in captivity was good for about fifty arrows, and this frog was about done. Antonio would soon release it and, once back to its usual diet, it would quickly regain its toxicity.

I felt happy for the soon-to-be-liberated frog, which would be looking forward to its next meal. I couldn’t say I was. The paca was boiling away. The old woman was mashing a bowl of manioc into a stew mixed with spinachy-looking leaves. One of the girls went out to take down what looked like a heavy white doily draped over the clothesline. This was manioc bread, which had been drying in the sun along with the laundry. On a shelf were some dusty cans of food, a bottle of rum, and a bag of rice, but they weren’t being offered. I resolved to eat the meal no matter what, so determined was I not to insult my generous hosts.

The paca, apparently cooked, was laid out on a plate. I willed myself to take at least one bite, but when Antonio sliced the whole animal into sections, he gave me the prized portion—the head. I knew that in the Amazon, refusing a meal was considered highly insulting but I couldn’t eat it. I had set my mind on eating some abstract body part, not a recognizable head. Revulsion welled up in me. My conscious
will could not overcome my emotional reaction. I had heard stories in which refusing a meal in the Amazon had proven fatal for a guest, and had I been in that kind of a situation, I know I would have been able to eat the rodent’s entire head. Even cannibalism becomes plausible when the situation is desperate enough. But survival was not at stake here, hence instinct could triumph over higher mental processes.

The family was disappointed. Antonio, however, having had considerable contact with outsiders, was not surprised by my antisocial behavior. He quickly withdrew the serving and replaced it with some manioc stew and a piece of bread. I was more than happy to eat that, while the others enjoyed their paca—boiled, I was assured, to perfection.

After the meal one of the younger girls brought out an English Bible and asked Antonio if I would read aloud from it. She didn’t understand English, so it didn’t matter what I read, her grandfather said; she just wanted to hear what English sounded like. I chose a page at random, read it aloud, and she was satisfied. In fact the whole family seemed pleased. It felt like the right time to depart, so Antonio and I both got up. The elderly woman motioned us toward the smoky blue fire that had been burning all day on the outside porch. Inside the aluminum pot was a smoldering termite nest. Antonio picked up a piece, crumbled it, and rubbed it on his face and arms. I did the same. I imagined I was performing some ritual asking for safe return to the camp, but Antonio said no, the termite smoke kept mosquitoes out of the hut. The powder would help keep them off us on the trail.

Going was much easier than coming. Antonio had reopened the trail just that morning so there was very little hacking to be done. As we walked it seemed like a good time to bring up something Antonio had said at the village.

“Antonio,” I said, “when you explained how to make a blowgun dart, you said it will break off if a
person
tries to get it out.”

He heard the question in my voice. “When I was young, there was warfare between tribes, and even shrunken heads. The arrival of the church stopped all that. Still, that’s the way I learned to make
darts. It works the same on animals as it does on humans.”

Now that the subject was open, there was something else I wanted to know. “Did you ever shrink a head?”

He continued to answer without quite answering. “The head of the fallen warrior was chopped off here,” he said, pointing to the interval just below my first neck vertebra. He explained that a vine was passed through the mouth and out the neck, then tied to make a strap so that the head could be carried back for preparation. The scalp was split down the middle, and the skin was peeled forward as the skull was removed. The facial muscles and the muscles around the temples and jaws were scraped out. The incision in the scalp was then closed with a running suture made from a tough vegetable fiber; the lips were sewn shut in the same way. The neck hole was sewn with a “purse-string” type stitch, so that it could be easily opened to fill the head with hot sand and then shut tight. As the heat shrank the skin, the facial features were molded to create a fearsome look. The sand, once it cooled, was emptied and replaced several times until the head was reduced to the proper size. The technique required the skills of a surgeon, pathologist, and sculptor, but when done properly, it prevented the dead warrior’s spirit from avenging his death.