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In 1985, Harvard University botanist Wade Davis traveled to Haiti in search of the poison powder called coupe poudre, allegedly used to cause the death-like trance state induced in the process of zombification. His sponsors believed that if such a drug existed it would have valuable pharmacological usage. He published the results of his findings in two books The Serpent and the Rainbow (1985), and Passage of Darkness: The Ethnobiology of the Haitian Zombie (1988). In essence, Davis claimed that yes, there are indeed "zombies," and that they are created, at least in part, by a poisonous powder. But, Davis maintains that the poison in and of itself is not enough to create a zombie, rather that "set and setting" must be taken into account (2). This is the distinction that defines the field of ethnobiology, the idea that physical, social and psychological settings inform biological interactions.
According to Davis, the active ingredient in coupe poudre is tetradotoxin, which is found in the liver and the ovaries of some species of Puffer Fish. Five hundred times more deadly than Cyanide, tetradotoxin is a potent ion channel blocker which while it can be fatal, in smaller (minuscule) doses leads to a near-death state wherein metabolic functions are so depressed that the poisoned person is thought to be dead (3). Tetrodotoxin "specifically and reversibly binds to a pocket on the outside of the sodium-ion channel in the peripheral nerves. This blocks the channel so that Na+ cannot enter, thus preventing the reversal of polarity that constitutes the action potential effectively shutting down the propagation of the nervous impulse" (4). The horrifying upshot of all this is that total body paralysis is induced, although the brain and senses stay alert. This is not good news for the victim, who is thus mistaken for dead and buried, much to their horror.
In addition to tetradotoxin, several other types of poisons have reportedly been detected in coupe poudre. Datura metel and Datura stramonium, both known as "zombie cucumber," are two such species of plants, which are hallucinogenic and cause amnesia. Another species used in the powder is Mucuna pruriens, a plant with stinging hairs and one which contains "psychomimetic constituents and may have hallucinogenic activity(4). These poisons constitute the powder, which is surreptitiously administered to the skin of the intended victim. But, the horror does not end there. The effects of the coupe poudre wear off in about 10-12 hours. The victim is then disinterred and fed a paste made of atropine and scopolamine, dissociative hallucinogens that impact on the neurotransmitters and endorphins in the brain. Yet, the drugs and the trauma alone are not enough to create a zombie, according to Davis.
To better illustrate Davis' argument for an ethnobiological understanding of the zombie phenomenon and how it is culturally bound, we need to take a closer look at the Puffer Fish. Those familiar with sushi know that the flesh of the Puffer Fish, known as Fugu, is considered a great delicacy in Japanese culture. The meat is very delicious, but difficult to prepare without contaminating it with the deadly tetradotoxin. Only highly trained chefs with special licenses are allowed to prepare the fish and even so several people die each year from eating improperly prepared Fugu. Very slight traces of TTX cause a slight tingling sensation in the tongue and lips and this, together with the thrill of danger, may contribute to the popularity of Fugu (4). In addition to Fugu-related deaths, there have also been reports of incidents of people being buried alive when they have gone into a "deep suspended coma" as a result of eating Fugu (3). However, there have been no accompanying reports of zombiism. Davis would contend that this is because the TTX, which is a psychoactive drug, one whose effect is related to specific personal experience, will have different effects depending on who one is and what one's socialization and expectations are (2). In the case of Haitians who have grown up with, if not direct personal knowledge of voodoo, the lore associated with it, they have been socialized to recognize both the possibility and the process, and are attuned to the appropriate effects of the drug, i.e. zombification. The zombie is so much an accepted part of Haitian culture, and indeed taken so seriously, that the Haitian Penal Code lists making someone into a zombie a form of murder (5). This is not unlike the idea behind placebo effect, where the belief that something works is a great determinant in achieving the desired effect.
Of course, Davis' is not the last word on the issue of the Haitian zombie. As recently as last year scientists were busily attempting to refute Davis' claims. The British journal The Lancet reported the findings of researchers Roland Littlewood, a British anthropologist and Dr. Chavannes Douyon of the Polyclinique in Port-au-Prince, Haiti, who concluded that many so-called zombies may in fact be individuals with psychiatric disorders and brain damage (5). While these researchers speculate on the causes of these disorders, positing epilepsy, oxygen starvation of the brain, and fetal alcohol syndrome, I do not find their observations to be inconsistent with Davis' findings. It seems to me that both the effects of the drugs, as well as the trauma associated with zombification would result in the apparent catatonic schizophrenia that Littlewood and Douyon observed in their clinical studies.
The larger questions raised by the existence, or non-existence, of zombies speaks to the very essence of our understanding of consciousness. In Haitian voodoo imaginary a zombie is revived without retaining his soul, or his self-consciousness, or indeed, his mind. But, leaving aside the religious-laden issue of whether or not one has a soul, death is the end of life and consciousness. The voodoo zombie is not in fact then a revived dead person, but a living person who has been brain-damaged. What is interesting is the interest that the Haitian model has sparked in another kind of zombie, a theoretical model, known as the philosophical zombie, or p-zombie. A p-zombie is a human body without consciousness that would nevertheless behave like a human body with consciousness. To some this constitutes a contradictory notion and thus an impossible conception. If it behaves like a person and is indistinguishable from a person, then it is a person (6). Others argue that a p-zombie would be distinguishable from a person even though indistinguishable from a conscious person, because it is stipulated that it is not conscious even though it is indistinguishable from a conscious being (7). (8). At the heart of this debate is the question, what is consciousness? Can consciousness be reduced to a set of materialistic functions? Functionalism implies that life is independent of its material substrate. "Life is ascribed to an emergent property of biochemical processes and functional activities. The contrary viewpoint is Vitalism, which contends that functional descriptions fail to consider or explain an "essential unitary one-ness," which they describe variously as "life force," "Úlan vital," or "life energy." Therefore, consciousness is more than brain processes and neurological functions and no adequate account of consciousness will ever be produced that is "reductionist," i.e., completely materialistic (9).
Important metaphysical and ethical issues hinge on whether or not there can be p-zombies. For instance, can machines be conscious? If we create a machine that is indistinguishable from a human being, would our artificial creation be a "person" with all the rights and duties of natural persons? It is possible to conceive of a machine which "perceives" without being aware of perceiving. In fact, such machines already exist: motion detectors, touch screens, tape recorders, smoke alarms, certain robots. An android which could process visual, auditory, tactile, and olfactory input but which would lack self-consciousness, i.e., would not be aware of perceiving anything, is conceivable. We can even conceive of such machines resembling humans in the flesh. How would we distinguish such automata from persons? The same way we do now: by the imperfect and fallible methods of conversation and observation. Self-consciousness or the lack of it would ultimately distinguish an automaton from a person. "Visual perception" by a motion detector is unlike visual perception by a person just because of the difference in awareness of perception, i.e., self-consciousness. A smoke detector might "smell" certain chemicals, but it does not process odors the way a person does. And, just how exactly can we know if anyone, beside ourselves is truly self-aware, truly conscious? The truth is that we can't know for sure; we must take each other's word for it. If you tell me you are conscious, I have to believe you, even if you have formerly been my toaster.
Personally, I don't believe that there are such things as zombies, or p-zombies, (by their respective definitions) not because the evidence is overwhelming but because in the absence of overwhelming evidence, not believing is the more ethical standpoint. In light of a human history that has ever been quick to jump to exclusion, to believe that something that looks like a person and acts like a person is somehow not a person is a dangerous proposition. It is this very notion that fostered and perpetuated the practice of slavery. So when I think about the ethical questions regarding how we should treat androids which are behaviorally indistinguishable from human beings, or zombies for that matter, I think that if we stipulate that such creatures are persons with rights, then they will be persons; otherwise, they will not be persons. The concept of personhood, is not a matter of discovery, but of stipulation.
2) Passage of Darkness: Ethnobiology of the Haitian Zombie , book review
3)"Eye of Newt, Skin of Toad, Bile of Puffer Fish," , from California Wild
4) Cellular Neuroantomy and Neurophysiology , from Neuroscience Lecture Notes by E. Adler
5)"Zombis May Not Be What They're Reputed To Be,", from The Doctor's Guide, in response to The Lancet article
6)"The Unimagined Preposterousness of Zombies,", by Daniel Dennett
7)"Self-Ascription Without Qualia: A Case Study," , by David Chalmers
8)"In Defense of Impenetrable Zombies," , by Selmer Bringsjord
9)"Quantum Vitalism," , by Stuart Hameroff
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