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From The Cosmic Serpent by Jeremy Narby

"Scientific studies of hallucinogens focused mainly on a product that is not really hallucinogenic; researchers neglected the natural substances, which have been used for thousands of years by hundreds of peoples, in favor of a synthetic compound invented in a twentieth-century laboratory."

FOR SEVERAL WEEKS, I went over the scientific literature on hallucinogens and their supposed effects on the human brain.

      Here is a fact I learned during my reading: We do not know how our visual system works. As you read these words, you do not really see the ink, the paper, your hands, and the surroundings, but an internal and three-dimensional image that reproduces them almost exactly and that is constructed by your brain. The photons reflected by this page strike the retinas of your eyes, which transform them into electrochemical information; the optic nerves relay this information to the visual cortex at the back of the head, where a cascade-like network of nerve cells separates the input into categories (form, color, movement, depth, etc.). How the brain goes about reuniting these sets of categorized information into a coherent image is still a mystery. This also means that the neurological basis of consciousness is unknown.(2)

If we do not know how we see a real object in front of us, we understand even less how we perceive something that is not there. When a person hallucinates, there is no external source of visual stimulafion, which, of course, is why cameras do not pick up hallucinatory images.

      Strangely, and with few exceptions, these basic facts are not mentioned in the thousands of scientific studies on hallucinations; in books with titles such as Origin and mechanisms of hallucinations, experts provide partial and mainly hypothetical answers, which they formulate in complicated terms, giving the impression that they have attained the objective truth, or are about to do so.(3)

      The neurological pathways of hallucinogens are better understood than the mechanisms of hallucinations. During the 1950s, researchers discovered that the chemical composition of most hallucinogens closely resembles that of serotonin, a hormone produced by the human brain and used as a chemical messenger between brain cells. They hypothesized that hallucinogens act on consciousness by fitting into the same cerebral receptors as serotonin, "like similar keys fitting the same lock."(4)

      LSD, a synthetic compound unknown in nature, does not have the same profile as the organic molecules such as dimethyltryptamine or psilocybin. Nevertheless, the great majority of clinical investigations focused on LSD, which was considered to be the most powerful of all hallucinogens, given that only 50-millionths of a gram brings on its effects.(5)

      In the second half of the 1960s, hallucinogens became illegal in the Western world. Shortly thereafter, scientific studies of these substances, which had been so prolific during the previous two decades, were stopped across the board. Ironically it was around this time that several researchers pointed out that, according to science's strict criteria, LSD most often does not induce true hallucinations, where the images are confused with reality. People under the influence of LSD nearly always know that the visual distortions or the cascades of dots and colors that they perceive are not real, but are due to the action of a psychedelic agent. In this sense, LSD is "pseudo-hallucinogenic."(6)

So the scientific studies of hallucinogens focused mainly on a product that is not really hallucinogenic; researchers neglected the natural substances, which have been used for thousands of years by hundreds of peoples, in favor of a synthetic compound invented in a twentieth-century laboratory.(7)

      In 1979, it was discovered that the human brain seems to secrete dimethyltryptamine—which is also one of the active ingredients of ayahuasca. This substance produces true hallucinations, in which the visions replace normal reality convincingly, such as fluorescent snakes to whom one excuses oneself as one steps over them. Unfortunately, scientific research on dimethyltryptamine is rare. To this day, the clinical studies of its effects on "normal" human beings can be counted on the fingers of one hand.(8)

  1. See Crick (1994, pp.24, 159) on the visual system, and more broadly Penrose (Shadows of the Mind, 1994) and Horgan (Scientific American 271(1):88-94, 1994) on the current limits of knowledge about consciousness.

  2. Among the exceptions, Hofmann (1983, pp. 28-29) writes: "As yet we do not know the biochemical mechanisms through which LSD exerts its psychic effects"; Grinspoon and Bakalar (1979, p. 240) write on the main effects of hallucinogens: "The only reasonably sure conclusion we can draw is that their psychedelic effects are in some way related to the neurotransmitter 5-hydroxytryptamine, also called serotonin. Not much more than that is known"; and Iverson and Iverson (1981) write: "We remain remarkably ignorant of the scientific basis for the action of any of these drugs." See the bibliographies in Hoffer and Osmond (1967) and in Slade and Bentall (1988) for an overview of the numerous studies on hallucinations and hallucinogens during the 1950s and 1960s.

  3. Schultes and Hofmann (1979, p.173)

  4. Psilocybin, which is found in over a hundred mushroom species, is a close variant of dimethyltryptamine, as Schultes and Hofmann (1980) write: "Degradation studies showed psilocybin to be a 4-phosphoryloxy-N,N-dimethyltryptamine. Hydrolysis of psilocybin gives equi-molecular amounts of phosphoric acid and psilocin, which is 4-hydroxy-N,N-dimethyltryptamine" (p.74). LSD is 100 times more active than dimethyltryptamine. See Hofmann (1983, p.115) for the comparison between LSD and psilocybin, and Strassman et al. (1994) for an estimate of the basic dose of dimethyltryptamine.

  5. Grinspoon and Bakalar (1979) write: "Used to describe the estheticized perception or fascination effect, enhanced sense of meaningfulness in familiar objects, vivid closed-eye imagery, visions in subjective space, or visual and kinesthetic distortions induced by drugs like LSD, 'hallucination' is far too crude. If hallucinations are defined by failure to test reality rather than merely as bizarre and vivid sense impressions, these drugs are rarely hallucinogenic" (pp. 6-7). However; these authors consider that the term "pseudohallucinogenic" is awkward, even if it describes precisely the effects of substances such as LSD and MDMA ("Ecstasy"). Slade (1976) writes: "The experience of true hallucination under mescalin and LSD-25 intoxication is probably fairly infrequent" (p.9). For a discussion of the concept of "pseudo-hallucination," see Kräupl Taylor (1981). Regarding the evolution of the relationship between science and hallucinogens, see Lee and Shlain (1985). Finally it should be noted that the synthetic compound known as "Ecstasy" differs from the other substances mentioned here in that it appears to be neurotoxic and to destroy the brain's serotonin-producing cells (see MeKenna and Peroutka 1990).

  6. Besides the 72 ayahuasca-using peoples of Western Amazonia, there are those who sniff dimethyltryptamiue-containing powders of vegetal origin, or who lick dimethyltryptamine-containing pastes. These pastes and powders are made from different plants (Virola, Anadenanthere, etc.) depending on the region. Sniffing dimethyltryptamine powders also seems to have been a custom among the indigenous peoples of the Caribbean, until they were physically eliminated during the sixteenth and seventeenth centuries.

  7. As I noted in Chapter 2, the exact chemical composition of ayahuasca remains a mystery. It should be pointed out that, contrary to the recent scientific studies which indicate that dimethyltryptamine is the brew's main active ingredient, ayahuasqueros consider that Banisteriopsis caapi (containing the beta-carbolines) is the main ingredient, and that Psychotria viridis (containing the dimethyltryptamine) is only the additive—see Mabit (1988) and Mabit et al. (1992). Regarding scientific research on the effects of dimethyltryptamine, the studies by Szára (1956, 1957, 1970), Sai-Halasz et al. (1958), and Kaplan et al. (1974) all consider this substance as a "psychotomimetic or a psychotogen," an imitator or a generator of psychosis. The study by Strassman et al. (1994) is the only one that I found with a neutral approach. However, all of these studies agree on one point: Dimethyltryptamine produces true hallucinations, in which the visions replace normal reality convincingly. As Strassman et al. (1994) write: "Reality testing was affected inasmuch as subjects were often unaware of the experimental setting, so absorbing were the phenomena" (p. 101). Finally it is worth noting that there are several interesting non-scientific studies, provided by people who have used this substance, published in Stafford (1977, pp. 283-304), as well as the writings of Terence McKenna (1991).