Monday, April 8, 2013

The Biology of Zombies

Last week, I decided to do a fun presentation for my intro to biology students about the biological possibility of zombies.  Most of them thought it was interesting stuff (some of them thought I was stupid, but "so what, who cares?"), and I had a lot of fun putting together my presentation.  So I thought I'd share some of the high points for my blog readers!

First of all, what makes a zombie?  How are they biologically possible if they are not dead, but not alive?  Dr. Steven Schlozman gives an overview of the anatomy of the brain and what areas would need to be dysfunctional for certain zombie characteristics.

So how would the zombie apocalypse begin?  Most likely, it would spread as an infectious disease caused by one of several pathogens.  A pathogen is simply an organism that causes disease.  This includes bacteria, viruses, fungi, parasites, and prions.  Each pathogen has certain characteristics that would make it well suited to spread the zombie plague - additionally, some examples of these real-life diseases have been documented to present zombie-like behaviors in various animals, including humans...

Viruses come in many varieties, and therefore can cause different symptoms.  Some can integrate themselves into your own DNA (like HIV), some can evolve/adapt rapidly (like influenza virus), and many have a rapid rate of transmission and can infect quickly.  Gypsy moth caterpillars become infected by baculovirus, which causes them to zombie crawl up a tree where they "liquify" and drip viral fluid onto other healthy caterpillars.

Prions are misfolded protein units that affect the brain, leaving "spongy" holes in the tissue.  They are transmitted via ingestion, and cause diseases such as bovine spongiform encephalopathy, or mad cow disease. Kuru is a disease that caused an epidemic amongst the Fore tribe in Papua New Guinea.  It caused tremors, poor coordination, and slurred speech.  It was discovered that this was a prion disease, passed on due to cannibalism.

Fungi can spread easily due to the airborne transmission of its spores.  They can cause superficial infections of the skin, or systemic infections of internal organs.  Some fungi, like Cordyceps, can act as a parasite - hijacking a host's body, such as an ant, to use its precious resources in order to survive and spread.

Parasites, as mentioned above, infect a host and depend on the host's body as a resource to feed, grow, and reproduce.  The jewel wasp is a parasitic predator, infecting cockroaches with a neurotoxin transmitted by their sting.  This toxin affects the roach's brain, causing it to turn into a "zombie-like" state.  The wasp then uses this zombie body as a living incubator for its eggs.  When the larvae hatch, they eat the roach and go on with their lives.
If one of these pathogens made the jump to infect humans, it's possible that a zombie plague could sweep the globe.  Of course, they are fictional characters, but we can't always predict what is a possibility in the future.  The Centers for Disease Control even released a "Zombie Survival Guide" a couple years ago.  What do you think?  Are you prepared to survive the zombie apocalypse?!

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