DO ZOMBIES FART?

Our usual weekend ritual involves waking up to National Public Radio---NPR.  Elaine and I both enjoy the Sunday puzzle featuring Will Shortz.  This past Sunday morning’s potpourri of NPR reportage included a segment from Los Angeles on actors training for potential roles in haunted houses, which is timely for impending Halloween.   One subgroup was learning how to portray zombies, currently very “in” given the tremendous popularity of TV shows like “The Living Dead”.  That segment got me to thinking (I free associate a lot) about some of the practicalities of life (do I mean un-life here?) as a zombie.

OK, let’s cut to the chase here.  I was wondering about zombie flatulence.  Do they or don’t they?  On the positive side, we know zombies are supposed to smell bad.  But that could just be because of death and decay, so isn’t definitive.  On the negative side, they’re dead, aren’t they?  Well, that’s ambiguous too.  So, it seemed a good time to analyze the biochemistry and physiology of the undead to see what the answer should be.  This turns out to be surprisingly easy to do while lying in bed half asleep trying to tune out the “inside the beltway” analysis of current events that NPR tends to favor.  Or the discussion of sports by a know-nothing NPR reporter from a second tier Ivy League college who doesn’t understand sports are frequently played west of the Mississippi River.  But I digress from the main point here. 

What do we know about the biochemical origins of the gas one passes during an episode of flatulence?  That’s easy.  It’s mostly a product of anaerobic metabolism by bacteria, and perhaps also yeasts, in the colon, and rich in methane.  Those pesky bacteria don’t have to die just because the zombie did.  In fact, they should thrive on the normal zombie diet of slow moving humans, and the increased anaerobic environment inside an undead corpse.  So, biochemically at least, the starting materials for making gas should be present in the zombie’s gut and the requisite bacteria for metabolizing these compounds to gaseous products should be thriving in that milieu post mortem, at least as long as the zombie keeps eating.

How about the physiology of the process?  We find most, or all, of the active gut bacteria in the colon. The stomach and small intestine are normally nearly sterile.  Intestinal gas is a mixture of (usually) small amounts of air that is swallowed when eating or drinking and gases produced within the digestive tract as a by-product of digesting certain types of food, or of incomplete digestion.   Undigested, or partially digested, food residues that reach the colon are fermented by the viable microorganisms present.   Therefore, a combination of the composition of the microbiota and the composition of the diet are the primary factors that will determine the volume of flatus produced.  Diets designed to reduce the amount of undigested fermentable food residues arriving in the colon significantly reduce the volume of flatus produced.  As with living animals, the saying “we are what we eat” defines the extent of the potential problem of flatulence in zombies.  

It’s not clear whether the absence of peristalsis will prevent transport of undigested food from the small intestine to the colon in a zombie, but perhaps gravity will suffice for transport downwards since all of the valves and sphincters relax and become flaccid in the undead state.  If the zombies feed only on humans who’ve eaten meat, fats, and simple carbohydrates, there shouldn’t be issues with zombie flatulence.  However, to answer our initial question, if the zombie’s victims eat complex carbohydrates, we can anticipate that the zombie will indeed fart.

            Yet another issue with Zombie farting exists.  “Gas incontinence" can be defined as loss of voluntary control over the passage of flatus. It is a recognized subtype of fecal incontinence, and is usually related to minor disruptions of the continence mechanisms.  As we consider the implications of this for zombies, we have to recognize the principle that things can always be worse. Gas incontinence is considered by some experts to be the first, and sometimes only, symptom of faecal incontinence.  Odor, whether produced by the dead, the living, or the undead, flatulence or fecal, is still an unpleasant odor and just varies by degree.

Prevention:  Probiotics (live yogurt, kefir, etc.) are reputed to reduce flatulence when used to restore balance to the normal intestinal flora. Live (bioactive) yogurt contains, among other lactic bacteria, Lactobacillus acidophilus, which may be useful in reducing flatulence.  Coating potential zombie victims with yogurt could be an effective strategy for decreasing the problem of zombie flaulence, if indeed it exists.  On the other hand, we should bear in mind the concept that being dead doesn’t mean you can’t still be flatulent.   If death at the hands of a zombie seems unavoidable, then revenge may be a consideration.  A last meal rich in legumes and a bowl of chili may be indicated in these circumstances.