Electricity, nerves and the ethnobiology of zombies

Does the legend of zombies have a natural and scientific explanation?

"Death is not the greatest loss in life. The greatest loss is what died inside us while we were alive." Norman Cousins

Clairvius Narcissa was not a likable person to those around him. He fought non-stop with his family members, amassed wealth on the backs of others and was the illegitimate father of several children, all of whom he refused to accept responsibility for. After a particularly bitter fight with his brother, Narcissa became bedridden and hospitalized in Haiti, vomiting blood. In a short time he began to suffer from breathing difficulties, low body temperature and extremely low blood pressure and his condition rapidly deteriorated. Only two days after hospitalization, Narcissa was pronounced dead, to the sound of his sister's cries, and he was buried the next day.

This is the point where the story takes a chilling turn in the Hollywood direction, as by nightfall Clairvius Narcissa has turned into a zombie.

A quick jump of eighteen years forward in time will bring us to the year 1980. Narcissa's sister is walking to the market in Toma, when suddenly a man approaches her and claims to her that he is her lost brother Clairvios, and even introduces himself by the affectionate nickname that was known only to the close family members. The excited nurse finds it hard to believe, but listens with wide eyes to the horror story that her lost brother unfolds before her.

It turns out that Narcissa's death was determined prematurely. His heartbeat slowed and weakened to the point where he could not be heard, and his lips took on the bluish hue common to the dead. But beneath that gloomy facade, Narcissa's mind remains alive and functioning. He remains conscious, but without control of his body. He even heard his sister's cry, and could feel the pain as his body was thrown into the coffin. The nails of the coffin pierced his face, but he remained as motionless as a dead body.
Only after the coffin was buried in the ground and covered with dirt did Narcissa regain control of his muscles. But then it was already too late. His strength was not enough to get out of the coffin, and he prepared himself for death - and hoped that this time it would come quickly and mercifully.

After some time - hours or days from the time of the burial - Narcissa heard human voices, and dared to hope that someone in the upper world realized the mistake and came to rescue him from the coffin. But it was not Ropa Rahman who opened the lid of the coffin. It was Bokor - one of Haiti's idol doctors - who ordered his servants to dig in the ground and rescue Narcissa. Only then did the ex-dead realize that the greatest nightmare of the people of Haiti had come true for him. He's about to turn into a zombie.

In Haiti, pagan medicine is like a profession. The Bokor is skilled in the use of both drugs and poisons and, according to the residents' belief, controls the faucets of the black magic arts. For these reasons, the locals are careful not to upset their sorcerers, and they in turn try not to violate the limits of the law, which imposes the death penalty for creating zombies. But sometimes the temptation is just too strong...

According to Narcissa's claim, his brother decided to take revenge on him in a particularly painful way, and paid Bokor to turn Narcissa into a zombie. The sorcerer's servants pulled Narcissa's body out of the ground and beat him to the core of his remaining senses. Then his runaway body was marched to the idol doctor's sugar plantation, and there he labored arduously for two whole years, like a zombie for everything.

On his return to the family, eighteen years later, Narcissa said that this period was like a dream. His desires were suppressed to zero, and he walked the fields haunted by hallucinations. He worked from morning until night, with almost no food, hunting on the side with the other zombies who were Bokor's servants. Slavery ended only when the al-Bukur died, and his slaves escaped to freedom.

Narcissa spent the next few years slowly recovering his mind, wandering around Haiti. The letters he sent to his family went unanswered, and he began to understand that his brother wanted to be left in custody. Only after many years did he gather courage and return to his native village, where he met his sister.

Narcissa's story became widely known, and received attention from scientists as well, especially from Dr. Lamarqua Duyon, director of the Haitian Psychiatric Institute. Doyon interrogated Narcissa and his family, cross-examined witnesses and decided that this case might constitute the first documented example of the creation of zombies. But Doyon did not believe that it was black magic, but a sophisticated use of poisons that exist in nature. The skilled scientist realized that such poisons - capable of slowing down the body's metabolism and dulling muscle control - have great potential for Western medicine, and to stand up to their nature he invited Wade Davis to Haiti. The 28-year-old Davis was a student for a doctorate in botany, and with a particularly adventurous spirit - a kind of Indiana Jones Kennedy. He gladly accepted the invitation, and joined three research trips, during which he interviewed pagan doctors throughout Haiti. The travels bore fruit, and Davis returned with five different powders that were capable, according to the Bokors, of killing a healthy person and bringing him back to life as a zombie.

All mixtures contained a variety of organic and synthetic substances. Most of them varied from one pagan doctor to another, but all included parts of the bodies of poisonous animals, such as toads and tree frogs. And most importantly: four of the five mixtures included samples from different species of puffer fish.

The puffers, or 'Abu Nafha', as they are known in slang, are fish that are able to swallow water and swell to twice their original size when in danger. If their double size does not deter the potential predator, some pufferfish also benefit from the protection of bacteria that live among them and produce a deadly nerve toxin called tetrodotoxin. This substance is one of the most poisonous in the world, and it is estimated that a single Abu-Nafha contains enough poison in his body to kill thirty adults. But the tetrodotoxin does not always kill. Mild poisoning with this substance can cause breathing difficulties, blue lips, low body temperature and even death - and in many cases consciousness is maintained until the actual moment of death. Davis saw the similarity between the symptoms of tetrodotoxin poisoning and Narcissa's medical condition, and claimed to have discovered the substance responsible for creating the zombies.

At this point, some of the mixture samples were transferred to laboratories around the world. The researchers in those laboratories discovered that the powders did contain a tiny amount of tetrodotoxin. But now only one mystery remains: how does the tetrodotoxin work? How does that simple molecule manage to paralyze the entire body, while leaving the person fully conscious?

In order to understand the mechanism of action of tetrodotoxin, we must better understand the most important cell in our body. By himself, he was nothing, nothing more than a messenger boy who receives messages and passes them on. But when it joins all its billions, it allows us to process information, record memories and accumulate knowledge. He gives us the ability to feel sorrow and joy, love and hate. In short, this cell is at the center of our being human, and it is the nerve cell.

The electricity and the nerves

As we saw in the previous chapters, all cells are surrounded by a fatty membrane, which is impermeable to molecules or ions charged with an electric charge, positive or negative. These ions exist in the aqueous solution outside and inside the cell, but because they are charged, they cannot pass through the neutral, lipid membrane. The only way they can cross the membrane is through flow in special channels that exist in the membrane, or by pumps that the cell activates specifically to throw certain ions out and others in.

Of those pumps, one of the most important in the cell is the sodium-potassium pump. The pump utilizes the cell's energy reserve to throw three sodium ions (Na+) out of the cell, and inject two potassium ions (K+) into the cell. If it were not for the pump's activity, the positive sodium ions would accumulate in the cell and attract water molecules through the membrane, which would fill and inflate the cell - until it explodes.

The activity of the pump is so important that even during rest, 30% of the cell's energy is wasted on sodium elimination. In the nerve cells, the operation of the pumps is essential for their normal activity, and they contain about a million sodium-potassium pumps on the surface of the membrane, which constantly consume almost two-thirds of the cell's energy.

The nerves in our body have one purpose: to transmit messages from one cell to another. Each nerve cell extends tiny antennae called dendrites, which receive chemical messages from other neurons. One neuron can have one dendrite, tens, thousands or even hundreds of thousands of dendrites. In this way, a single cell can receive and process information from thousands of other cells simultaneously.

The messages received from the dendrites are transmitted to the cell body and from there to the 'send channel', from which one long extension, known as an axon, comes out. The nerve cell uses an axon to transmit messages to other cells, by sending a wave of electrical voltage. The wave propagates through the axon until it reaches its end, where it causes a specific response, such as activating another nerve, contracting a muscle, or activating a gland.

Since the pumps constantly throw three positive sodium ions out of the cell, and bring back in only two positive potassium ions, it is clear that in a short time the amount of sodium ions outside the cell becomes greater than the amount of potassium ions inside the cell. Both types of ions have a positive charge, but since there are more positive ions outside the cell, there is an excess of positive charge outside the cell compared to inside the cell. To simplify the matter, the biophysicists treat the inner side of the cell membrane as negatively charged, because its positive charge is smaller than that of the outer side.

This situation, where the inner side of the cell membrane is negatively charged, and the outer side is positively charged, is actually the definition of an electric field. To determine the value of the electric field, the difference in charges between the outside of the cell and the inside of the cell is checked, and it is discovered that in normal cells its value is constantly at 70 millivolts. That is, the cell membrane is charged with a negative electric charge all the time. But in order to send the electrical message, the cell must reverse the charge on the membrane, making it positive for a short time.

The inversion process seems complicated at first glance, but when you get down to the bottom of things, it turns out that it is based on one of the most basic and simple laws of nature: the law of diffusion. This law plays an essential role in almost all processes in the cell, but especially in the transmission of messages by the nerve cell.

The law of diffusion describes the behavior of molecules, atoms and ions in a liquid. We witness its action every time we dip a tea bag into a cup of hot water, or watch uneducated children in the pool. If we dip the same tea bag in a cup of hot water, we will see a cloud of color slowly spread from the bag to the whole cup. The cloud contains the tea molecules, which spread everywhere, in an attempt to reach the same concentration of tea molecules throughout the glass.

If we left the bag in the glass for several days, the molecules would slowly reach all the liquid, until the concentrations were the same in every area of ​​the glass. This is exactly the law of diffusion, which states that molecules of a certain type always strive to move from an area where they are abundant (for example, the tea bag) to areas where they are less concentrated (for example, the rest of the cup).

When the dendrites of the nerve cell receive messages, they pass the information to the 'send point' - the place where the axon connects to the cell body. The cell membrane in that area is full of sodium channels. The channels are very different from the pumps: they do not require energy to operate, and can be regarded as simply 'holes' in the cell membrane, which allow the passage of only certain ions. Through the sodium channels the sodium ions can flow into the cell or out, according to the law of diffusion. In a resting state, the concentration of sodium outside the cell is much higher than inside the cell, so the sodium will strive to move into the cell. The electric field of the membrane also helps sodium to flow into the cell, because the inside of the cell is defined as negative and sodium is positive. All this means that as soon as the channels open, the sodium ions will flow through them into the cell at an enormous speed. In this case, the cell will accumulate excess sodium ions with a positive charge, and the charge difference on both sides of the membrane will quickly decrease, until the value of the electric field reaches zero.

At this point, the positive sodium ions will no longer feel the electrical force pulling them into the cell, but they will continue to flow in because their concentration inside the cell is still less than their concentration outside the cell. Within a thousandth of a second, the value of the electric field in that area will reach +50 millivolts. Only then will the cell reach a new state of rest, when the electric field of the membrane has become positive at that point.

We saw, then, that the opening of the sodium channels causes a change in the tension of the membrane. But how do the sodium channels open? Normally, the channels are closed and do not allow ions to pass through. When the charge difference between the two sides of the cell begins to decrease, as a result of the message transmitted from the dendrites, the electric field changes slightly. The channels are built as sophisticated machines that are sensitive to the electric field around them, and when it changes, they react and open, allowing the sodium ions to flow through them on their way to the interior of the cell.

The change in electrical voltage that occurs where the sodium channels open on the membrane is the electrical message transmitted by the nerves. Apparently, it is only a voltage change in a spot area, but this small change spreads quickly along the cell membrane, and causes the voltage to change in the adjacent areas as well. The voltage change also causes the sodium channels in those areas to open, and flow the positive ions into the cell. This is how the message is transmitted along the entire axon, when the voltage of each area changes in turn, until the end of the axon is reached and the nerve message is transmitted. (The myelin layer is also involved in the process, but we will discuss that in the next chapter)
But although the sodium channels play an important role in the cell, they also pose an existential threat to it. If the ducts had been left open, even for a few seconds, the cell would have blown its little soul. The excess ions would attract many water molecules into the cell, and the cell would swell and explode. for that reason,

The sodium channels have an automatic locking mechanism: a millisecond after the channels open, they automatically lock and the ions stop flowing into the cell.
But even closing the channels is not enough to restore the situation, because the cell is still flooded with the sodium ions that have penetrated inside. The pumps would take too long to remove them, so there is a second protection mechanism in the cell that ensures that the membrane voltage will return to negative. Just as a small change in voltage could open the sodium channels, so it is able to activate other channels as well - the inhibited potassium channels. These channels also open as a result of the change in voltage, but with a delay of a fraction of a second. Their opening allows the positive potassium ions inside the cell to escape quickly to balance the concentration difference.

On their way out, the potassium ions carry a large positive charge, which is removed from the inside of the cell membrane. And so we returned, in fact, to the initial situation: a large amount of positive ions outside the cell membrane, and a small amount of positive ions on the inside of the membrane. The membrane voltage returns to negative, and after a period of several thousandths of a second, the sodium channels will be released from their lock, and will be able to open again if the correct message is received.

The whole process describes the transmission of one electrical message in the nerve endings, which occurs in many neurons in our body incessantly. The nerves send commands and instructions to the muscles, glands and even other nerves, and it all starts with the action of the sodium channels that allow the change in cell membrane tension.
The tetrodotoxin, blamed for creating zombies in Haiti, is capable of disrupting the electrical message transmission process. The small and deadly molecule functions, in fact, as the stopper of the sodium channels. It sticks to the opening of the sodium channels and blocks the passage of ions through them. If there is no passage of ions into the cell, then the membrane tension cannot change and the nerves are unable to transmit the message to muscles or other nerves. The initial result will be a complete paralysis of the mental activity, of the skeletal muscles, of the muscles of the respiratory system and of the heart muscle. Considering all these, it was reasonable to assume that the poisoned person would die immediately. But fortunately for the poisoning victims, the tetrodotoxin does not affect all sodium channels equally. Some of the sodium channels are more immune than others to tetrodotaxin, so the nerve cells that contain them are able to continue their normal activity, even when the rest of the nervous system falters and collapses.

Where are those immune sodium pumps? It is difficult to find conclusive experiments with tetrodotoxin conducted on human nerve cells, but it is known that the tetrodotoxin-resistant pumps are present in the heart pacemakers in mice and the sensory nerves in frogs and snakes. From this it can be assumed that a well-measured amount of the tetrodotoxin given to a person may stop or delay the skeletal muscles and respiration, but leave the heart beating and maintain the operation of at least some of the nerves in the brain. And this, in fact, was Davis' main claim.

Through combination with toxins and other substances, the idol doctor causes his victim to enter a death-like state, while his heart beats slowly and weakly, so much so that the doctors are unable to locate the pulse. The 'deceased' is immediately sent to burial, and the morning arrives at the grave at night, after the effect of the poison has faded. But the brain requires oxygen to function, and it is likely that the victim, who has been in the coffin for many hours without a supply of fresh oxygen, sometimes reaches a state of partial brain death, despite the slow metabolism in which he is kept. Does brain death mimic zombie symptoms? This is possible, but unlikely. Instead, Davis claimed that the sorcerer and his servants anoint the fresh zombie with a herbal extract containing the seeds of the datura plant,

Datura seeds are known to cause hallucinations, are able to cause amnesia and cause dilation of the pupils and aversion to light. In addition, they can lead to loss of appetite and delayed digestion, speech problems and loss of sense of time. When the new zombie slave is under the influence of the drug, the Bokur leads him to the sugar plantations, where he continues to beat him with Datura every few days and uses him as cheap labor until the day he dies.

Back to reality

When Davis returned from Haiti in 1983, some of the zombie powder samples were given to researchers at the New York Psychiatric Institute. The researchers applied the powder to mice, and reported that the experimental animals entered a state of delayed animals, similar to that obtained as a result of eating the abu-nafha fish. This was sufficient proof for Davis, and he hastened to publish the results of the research in the scientific press. The storm did not hesitate to come.

The main problem was the amount of tetrodotoxin found in the powders. In order for the poisoning to cause a coma but not kill the victim, a terrifyingly precise amount of the substance is needed. It is difficult to see how the idol doctors of Haiti can accurately estimate the amount of poison in the powder extracted from fish. The strangeness increases when you remember that each fish contains a different amount of poison, because the poison is produced by bacterial populations in the fish's tissues. How can the Bokurs identify the correct amount of poison present in the Abu Nafha fish? And is there really enough tetrodotoxin to poison humans in the powders?

To try and get to the root of the matter, Kao and Yasumoto, a pair of researchers from Japan and the United States, tried to quantify the level of tetrodotoxin in the pollen samples by diluting it in water. They found that the amount of toxin inside is negligible, and should not affect humans or mice. Davis claimed in response that the tetrodotoxin must have been destroyed during the dissolution in water, and cited as circumstantial evidence the Bokors' instruction to spread the powder in places where it would come into contact with the skin, and not to drink it.
Another group from Switzerland, who tried to quantify the level of tetrodotoxin while maintaining a constant level of acidity, found that the amount was 320 times greater than that discovered by Kao and Yasumoto. In response, Kao and Yasumoto claimed that the Swiss used a method that does not differentiate between the tetrodotoxin and its inactive derivatives. They added and accused Davis of forgery, cheating, and tampering and covering up the evidence to fit the theory, at best, or making the whole story up out of his wild imagination at worst. Finally, they added that they know that Davis himself tried to apply the powder to mice, but to no avail.

Although the debate about the amount of tetrodotoxin in the powders has not been resolved to this day, the scientific community still refuses to believe that Haiti's pagan doctors are capable of creating zombies. Although, no one doubts the toxicity of the tetrodotoxin, but even if there are pagan doctors able to ascertain exactly the appropriate amount of the toxin, there is much circumstantial evidence against the zombie myth.

We know that people who are under the influence of Datura suffer from hallucinations and incessant nightmares, and believe that they are real and real. Narcissa reported that he was enslaved on a sugar plantation, but how can a man work when his worst nightmares constantly appear in front of him? And even if the drugged zombies are employed in simple mechanical operations, where are those sugar plantations hidden? Haiti today is one of the most densely populated countries in the New World. Where can you hide sugar plantations haunted by hallucinatory zombies?

Since 1983, more details have been discovered about the zombie phenomenon in Haiti, and it turned out that it is based in many cases on a mistake in identification. In an article published in 1997 in the prestigious medical journal The Lancet, three different cases of zombies in Haiti were presented. In all cases, the families recognized their deceased loved ones on the street, and adopted them back into the family. When those former zombies, all of whom suffered partial retardation, were examined by Western doctors. It was proven through DNA samples that two of them were not related to the adoptive families at all. In fact, when one of the former zombies was taken to the market square in a nearby village, she was recognized by her real family. In a short time, a great commotion developed in the market square, with the members of the two families accusing each other of black magic and turning the woman into a zombie.

It is clear, then, why zombie stories should be treated with great suspicion. But skepticism aside, one cannot help but admire the way in which natural and simple molecules can play with our bodies like puppets on strings. There is no doubt that a sophisticated use of these poisons may turn a healthy person into an automaton or a mindless plant, and it is possible that some of Haiti's pagan doctors found a crude and crude way to utilize the tetrodotoxin for their purposes. However, today's medicine is able to effectively and accurately utilize tetrodotoxin to treat heart problems and pain relief, and even in basic research conducted on nerve cells. In this way, one of the most toxic molecules in nature - and since Davis' research, also the most notorious - became a tool for medicine and understanding the human body.