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You
know you have a phenomenon when you can knit a
zombie.
These you can take apart and reassemble, just
like
real zombies. Knitting a zombie somehow weakens
the
argument that we use them to address our deep
seeded fears; these might show up at a baby shower.
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Some “experts” believe that zombies hold fascination for us
because of our need to address fears without directly confronting them. Death,
the breakdown of social order, chaos, perhaps science run amok – these are all
found in the zombie stories.
In fact, it could be proposed that all these fears stem from
the need for expected outcomes and a sense of finality. After you die, who
cares about control, order, or even diet – but what if you were condemned to be
undead? What if everyone else was undead and you had to deal with their lack of finality? We watch zombie
movies to deal with our own fears on a subconscious level.
Did you know that zombie legends may have some basis in
truth? In the early 1980’s an ethnobotanist
from Harvard named Wade Davis claimed to have found two potions used to create
zombies.
In Haiti, the fear of zombies has been present for many
years. Based in African folklore and maintained by the descendents of slaves
that revolted and remained in Haiti, witch doctors (bokurs) are very real
sources of reverence and fear for the average man and woman. Just how the
bokors managed to create zombies was the question asked by Dr. Davis.
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Ethnobotanists
are scientists that study different
civilizations
(ethno-) for how they use plants (-botanist)
in
medicine and culture. Mark Plotkin spent years with
tribes
in the Amazon studying the use plants by the
medicine
men. After returning with many plants from
which
to extract compounds, Plotkin started Shaman
Pharmaceuticals
to test the compounds for medicinal uses.
Plotkin now runs an Amazon Preservation organization.
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Davis claimed to have found a powdered potion that could
make a person appear to be dead.
Based on a toxin called tetrodotoxin, Davis said the powders were most commonly
blown into the faces of victims and the toxin would inhibit firing of voltage-gated
channels in the nerves. Heart rates would go to near zero and the affected
individuals would seem dead.
In many cases, tetrodotoxin doesn’t just make people appear
dead, it kills them for real. Blue ringed octopods, several species of fish, and other
animals contain this toxin and it will mostly certainly kill. The sushi dish
called fugu is a pufferfish that contains tetrodotoxin. Even when prepared
correctly (which takes a government issued license), the consumer will
experience numbness in their tongue and mouth. Davis stated that dosing the
victim often resulted in real death; making zombies is apparently not so easy.
After a hasty burial, the bokor would dig up the poisoned
victim before true death occurred, and a zombie slave was produced by giving a
second potion. This poison was based on a Jimson weed (Datura stramonium) extract, leading to the second name for the
plant, zombie cucumber.
Jimson weed extract is a psychoactive agent that leads to stupor
and amnesia, but no loss of consciousness. There said to be the basis of the
loss of free will, and slow dragging movements of zombies. In such a state, the
affected could be turned into slave labor, or used to frighten others into
compliance with the bokurs’ wishes.
Davis’ samples and explanations were not accepted by the
majority of the scientific community. The toxins described are very toxic;
small mistakes in dosage would most certainly be fatal. And a motive of
creating cheap labor is not convincing; most labor in Haiti is cheap.
But don’t try to tell that to the Haitians. They actually
have a law forbidding the creation of zombies. Article 249 of the code of laws
states, “It shall also be qualified as attempted murder the employment which
may be made against any person of substances which, without causing actual
death, produce a lethargic coma more or less prolonged.” Scary.
So let’s talk zombies. Some people will get into intricate
detail, but let’s confine ourselves to two kinds of zombies. One kind of zombie
was dead but is now reanimated by
some means – usually some kind of parasite or virus that brings some tissue
back to life. The other sort of zombie always remains living, but loses all
ability to direct its own thoughts and actions; it is driven only to acquire
flesh – usually bbrraains!
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The
top cartoon shows how the valves in your veins work to
keep
blood from pooling in the lower extremities. For veins
above
your heart, you don’t need the valves, so they don’t
have
them. On the bottom, you can see what happens in the
case
of varicose veins, when blood will begin to pool. The
picture
on the bottom right shows what happens when
valves
go bad (insufficiency). Can you get varicose veins
above
your heart – yes, but it usually requires
severe liver damage.
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If they have no heartbeat, how do they circulate their
blood? I saw one website that stated unequivocally that muscle movement
(contractions and relaxation) pushes the blood around the body. Ridiculous,
right? Not really. You do this every minute of every day. On the artery side of
our circulation, the muscle in our vessels work with the contraction of the
heart to push the blood along, but across the capillary bed, there is little
pressure left to push blood through the veins.
So you use the action of your large muscle groups to squeeze
the blood in the veins. When you walk, bicycle, or step dance, the contractions
push the blood up against gravity. Your veins have one-way valves, so after the
blood passes a valve, it won’t flow backwards. If this wasn’t so, all your
blood would end up in your feet, and you’d have to buy shoes like Shaquille
O’Neal’s.
On the other hand, if we are talking about living dead
zombies, then there are many possible biologic causes. Rabies is caused by a bacteria passed through the bite of an
infected animal. The result is an infection that can take one of two forms. In
furious rabies, the victim will display erratic behavior, aggressiveness,
foaming at the mouth, and will eventually start biting people.
The paralytic form of rabies will cause slow movements,
dragging feet, lack of coherent behavior, and foaming at the mouth. The foaming
is due to the inflammation of the throat that makes it so painful to swallow
that victims will choose to drool and foam instead. Either form of rabies could
mimic what we think of as zombies.
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The
top picture is Cujo, from the Stephen King story of the
same
name. The dog was huge, and then caught rabies from
a
little field animal. He lost all sense of personal hygiene and
liked
to bite anything that moved – just like zombies. Below is
a
photomicrograph of the negri (named for Adelchi Negri)
bodies
that appear in the brain tissue of rabies victims. They
stain
darkly and are made up of riboproteins made by the
rabies
virus.
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Most people believe that you get bit, and then you develop
rabies, so it is easy to put cause with effect. But a new study shows that rabies can incubate for decades before symptoms manifest. The man in question
showed signs while he lived in the U.S., but the organism he harbored is found
only in Brazil, a place he hadn’t lived or visited for many years, although he
did remember a biting incident in his home country. If the symptoms occur out
of nowhere, does that support or negate the idea that he might be a zombie?
If you want an example of living dead, look no further than African sleeping sickness (also called
trypanosomiasis). The bite of the tsetse fly transmits the Trypanosoma brucei parasite, which then takes up residence in brain.
The symptoms get progressively worse, starting with
headaches and moving through slurred speech and then to a zombie like state
with sleep being impossible at night and staying awake being difficult during
the day. They enter a living nightmare, unable to respond or act, until they
fall into a coma and die after a few weeks. Sounds like a zombie to me.
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African
sleeping sickness is an often fatal disease with parasites
invading
the brain and doing damage. Survivors are usually
permanently
brain damaged. The tsetse fly (below) is the vector
that
carries the trypanosome. While it takes a blood meal, it
vomits the organisms into the wound
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Recently, a study showed that things thought to be repellent to tsetse flies, such as smoke or human presence in a confined space, did not stop the flies from alighting on humans inside buildings. The number of
landings also increased as the temperature increased. Buildings must now be
considered a possible venue for disease transmission. But at least with this
disease you can just go to sleep, it isn’t like your ear will fall off.
Leprosy (Hansen’s disease), on the other hand, can present
some of the bizarre symptoms seen in zombies. The causative organism is Mycobacterium leporae, and has been
around for thousands of years. There was no treatment for most of those years;
an effective antibiotic regimen was not devise until the 1940’s. Because of
this, leper colonies were used for two thousand years to separate the victims
from the rest of the population. This is interesting, because it’s relatively
hard to catch Hansen’s disease.
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On
the left is a leprosy victim. Remember that leprosy itself
doesn’t
cause loss of body parts, but secondary infections are.
The
9 banded armadillo is one of the very few animals that is
susceptible
to leprosy, so it is often used in the laboratory. Below
on
the right, current treatments are very effective at alleviating
the
swelling and skin lesions associated with the disease. Leprosy
shouldn’t be considered a killing or disfiguring disease anymore.
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The disease has a very long course because it is a very slow
growing bacterium; the doubling time is about 14 days. M. leprae has a predilection for setting up shop in skin and
nervous tissue, and this is the reason it is linked to zombies. Leprosy itself
doesn’t cause body parts to fall off, but it does compromise the blood flow and
immune reaction in extremities.
Secondary infections can then gain a foot-hold and cause
loss of fingers and such. This tendency for loss of noses, ears, etc. is
exacerbated because the organism prefers it a bit cooler, so it tends toward
areas with lots of surface area and less blood flow. A new study shows that M. leprae causes damage to the olfactory bulb, affecting the size of the nervous tissue responsible for smell sense.
This would be especially bad for zombies, since they are said to act mostly on
a sense of smell to attract them to potential victims.
The damage to skin and nerves could additionally contribute
to a look of decay about the face and body, and a shuffling gait – also zombie
like properties. Even zombies don’t want to catch leprosy.
Next week, can we use rigorous biological analysis to
determine if zombies are a form of life? I sure hope so, or it’ll be a short
post.
For
more information or classroom activities, see:
Ethnobotany
–
Vein
valves –
Rabies
–
African
trypanosomiasis –
Hansen’s
disease –
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