Jeremy Narby was a young anthropologist studying the Ashaninca Indians in the Peruvian Amazon when he first took ayahuasca in the mid-1980s. The Indians had told him that ayahuasca was the source of their plant knowledge. They called it "forest television." Narby was interested, though skeptical.

He was less skeptical an hour after drinking the brew, when he found himself surrounded by two huge snakes, fifty-foot boas, who spoke telepathically to him, putting him in his place: "They explain that I am just a human being. I feel my mind crack, and in the fissures, I see the bottomless arrogance of my presuppositions. It is profoundly true that I am just a human being, and, most of the time, I have the impression of understanding everything, whereas here I find myself in a more powerful reality that I do not understand at all and that, in my arrogance, I did not even suspect existed." Later, the shaman tells him the snakes are known as "the mother of ayahuasca."

Ayahuasca, as Ralph Metzner is noted, is a "gnostic catalyst." It opens the door to those occult dimensions of psychic reality which are vigorously denied by modern rationalism. Like Michael Harner a generation earlier, Narby found himself forced to reevaluate his anthropological stance and his own beliefs after drinking yagé. His book, The Cosmic Serpent, is an attempt to interpret the visionary realms opened by ayahuasca in a way that might fit with a scientific worldview. He finds that the motif of snakes, especially twin serpents - the cadeceus of Hermes and the sign of Western medicine - appears worldwide in archaic myths of creation, and as kundalini, the Hindu occult symbol of the life force. Narby links the serpent or tangled snakes often beheld through ayahuasca with the twisted and twinned coils of DNA. He theorizes, "In their visions shamans manage to take their consciousness down to the molecular level." Shamans, according to Narby, receive images and information from DNA. DNA, a long snake-like spaghetti string of coded data, is also an aperiodic crystal, four atoms wide, that beams out photons. "The global network of DNA-based life emits ultra-weak radio waves, which are currently at the limit of measurement, but which we can nonetheless perceive … in hallucinations and in dreams," he writes. He theorizes that this transmission is the "vegetable gnosis" and collective consciousness of the natural world.

Detouring into molecular biology, Narby explores genetics and the Darwinian theory of natural selection. He finds that Darwin's theory does not seem to fit the development of the genetic code, an incredibly complex language packaged with a high-tech transcription program that appeared with the first bacteria, 3.5 billion years ago. The theory of natural selection also has to be stretched to explain the sudden explosion of animal species that started 543 million years in the past.

"Throughout the fossil record, species seem to appear suddenly, fully formed and equipped with all sorts of specialized organs, then remain stable for millions of years," Narby writes. Other psychedelic avatars share Narby's suspicion that what is going on in evolution is more than the result of endless chemical reactions. As Stanislav Grof, pioneering LSD psychoanalyst wrote, "The probability that human intelligence developed all the way from the chemical ooze of the primeval ocean solely through random sequences of random mechanical processes has been aptly compared to the probability of a tornado blowing through a gigantic junkyard and assembling by accident a 747 jumbo jet."

Even Francis Crick, one of the discoverers of the DNA double helix, found it necessary to advance the thesis that DNA was brought here on alien spaceships to explain how DNA could work as it does. Of course, such a hypothesis resolves nothing and only adds to the mystery.

Narby suggests that the scientific adherence to the theory of natural selection is a form of faith. His book falls within "the blind spot of the rational and fragmented gaze of contemporary biology." Against the postulates of reductive materialism, Narby believes that "DNA in particular and nature in general are minded. This contravenes the founding principle of the molecular biology that is the current orthodoxy." He suspects that the ayahuasca vine may be exactly what the shamans say it is: The sentient spirit of nature, the mind of the forest, which directly communicates with human beings through this chemical interface.

Narby makes a laudable effort to study ayahuasca by accepting that the ayahuasqueros possess real knowledge, rather than assuming, as most Westerners have for centuries, that the shamans were either schizophrenic, deluded, fakers, or at best fabulators. It is increasingly clear that shamanic practices have validity - for healing, for spiritual regeneration, telepathic communication, and other ways. It remains difficult for scientists to approach the subject rationally because shamans work with invisible psychic currents, "supersensible" forces, and the existence of such forces - such as the subtle currents recognized by Eastern traditions - are beyond the perimeters of what our tools can measure at this point. The existence of what cannot be quantified is not only ignored but vehemently denied by Western scientists, who forget that "absence of evidence is not evidence of absence." How can the rational perspective of the West comprehend a technology which makes use of invisible and seemingly unmeasurable forces? That will be a subject for the new century to explore. As Terence McKenna wrote, "Shamans speak of "spirit" the way a quantum physicist might speak of "charm"; it is a technical gloss for a very complicated concept."

The Cosmic Serpent is only one of many recent efforts by Western commentators to reinterpret the meaning of ayahuasca shamanism for the New World Order. In Shamanism, Colonialism, and the Wild Man, the anthropologist Michael Taussig explores yagé shamanism in Colombia, where ancient rituals have taken on new meanings in the wake of the cruel excesses of colonialism. Taussig's Mestizo sorcerors exorcise terror through laughter and and improvisation, "building and rebuilding neocolonial healing rituals wherein fate is wrested from the hands of God and transcribed into a domain of chance and perhapsness." Most anthropologists believe that all religious rituals work to order and unify society. Taussig found the opposite with yagé: The ceremonies opened up a transcendent space for chaos. He quotes Roland Barthes on the idea of a "third" or "obtuse meaning," outside of what can be expressed in language or defined by cultural analysis:

... the obtuse meaning appears to extend outside culture, knowledge, information; analytically it has something derisory about it; opening out into the infinity of language, it can come through as limited in the eyes of analytic reason; it belongs to the family of pun, buffoonery, useless expenditure. Indifferent to moral or aesthetic categories (the trivial, the futile, the false, the pastiche), it is on the side of the carnival. (Barthes, Image, Music, Text)

For Taussig, shamanism preserves a place for knowledge that can heal because it falls outside of any system. Yagé visions open up constellations of the unknown, obtuse meanings, and "chance and perhapsness."

Narby collected some of the more nuanced accounts of shamanic practices in an anthology, Shamans through Time. Read chronologically, the essays in the book make it clear that terms for studying spirituality, shamanism, and mysticism are starting to shift radically. Recent texts include one from the anthropologist Edith Turner, who recalls seeing "a spirit form" during an exorcism ritual in Zambia:

"I saw with my own eyes a large grey blob of plasma emerge from the sick woman's back," she writes. "Then I knew the Africans were right, there is spirit affliction, it isn't a matter of metaphor and symbol, or even psychology. And I began to see how anthropologists have perpetrated an endless series of put-downs in regard to the many spirit events in which they have participated - participated in a kindly pretense." Transformed by her own experiences, Turner decries the "religious frigidity" of modern anthropologists.

The anthropologist Francoise Barbira Freedman studied the Lamista Indians in the Peruvian Amazon. In the book The Ayahuasca Reader, she tells how she apprenticed herself to a tribal shaman, taking ayahuasca and learning about the local tensions between sorcerors and shamans. "As I progressed in my apprenticeship, the increased awareness that there was no neutral position within reach frightened me," she writes. "I was now in the game." During one ayahuasca trip, she experienced animal transformation first hand. She became a jaguar stalking through the forest. The elder shaman visited her in the form of an eagle, communicating telepathically. "Nothing I ever read about shamanic animal metamorphosis could have prepared me for the total involvement of my senses, body, mind, in this process." This vision was a sign of acquisition of certain shamanic powers, but she was told by the shaman that it also carried dangers with it. From then on, if she continued learning, she would have to constantly protect herself from sorcerors and malevolent spirits by magical means. Freedman decided to end her apprenticeship at this point. "There was no longer any possible vantage point for me as an anthropologist other than that of the shamanic rainbow," she notes. She wonders how the moral structures of Western culture can absorb or adapt this ancient and ambiguous practice.

For his part, Narby thinks that ayahuasca could be a valuable tool for the modern biologist, who could use the substance to interrogate the "mind of nature" directly. Recently, Narby brought three European molecular biologists down to visit an Amazonian shaman. During their trances, they attempted to ask direct questions of the ayahuasca spirit relating to their areas of research. All received answers to their queries. For example, one genetic researcher found herself transformed into a protein flying above a long DNA strand, and was able in this way to understand the meaning of certain patterns in what had previously been considered "junk DNA":

She saw DNA sequences known as "CpG islands," which she had been puzzling over at work, and which are found upstream of about sixty percent of all human genes. She saw they were structurally different from the surrounding DNA and that this structural difference allowed them to be easily accessed and therefore to serve as "landing pads" for transcription proteins, which dock on to the DNA molecule and make copies of precise genetic structures.

All of the biologists were intrigued by what they found, and two of the three felt they had communicated with an "independent intelligence."

When Dennis McKenna, Terence's botanist brother, drank ayahuasca with the Uniao do Vegetal, a Brazilian syncretic religion that uses ayahuasca as its sacrament, he was turned into a sentient water molecule in the jungle soil, pulled up through a vine's roots to experience the miraculous molecular processes of photosynthesis in its leaves. "Somehow I understood - though no words were involved - that the Banisteriopsis vine was the embodiment of the plant intelligence that embraced and covered the earth," he recalled. At the end of his vision, a voice told him, "You monkeys only think you're running things."

Yage opens up a playful zone of "chance and perhapsness," yet it seems to convey particular messages about the biological world, and often creates specific models of natural processes. More than other psychedelics, it seems to dissolved the rigid categories that modern culture has erected between poetry and science, medicine and magic, knowledge of the self and knowledge of the universe. If the "Vine of Souls" was a trademarked brand, it would be this book's official sponsor.