Why do they eat poop? The answer might save your life!

Anyone who has ever kept a pet rabbit has seen Mister Hoppypants gobble up feces like it was Cocoa Puffs.  Bunnies like poop!  So do hamsters, guinea pigs, and koalas.  Gorillas, elephants, hippopotamus.  Puppies.  Terrestrial isopods.  Chimpanzees.  The list goes on and on.  Animals have a culinary craving for kaka!

Assuming that you do not occasionally sample your own stool, news of this phenomenon may be somewhat hard to swallow. (ba-dum-bump)  There are, however, a number of good reasons why it makes biological sense.

For herbivores that (lacking the enzyme to break down plant cell walls) are unable to completely digest food the first time around, re-eating food as feces gives the digestive system more time to break it down.  It may also help the animal reclaim limiting vitamins and nutrients.  It might remove cues that a predator could use to find the pooper.

Or, as Nicola Jones writes for Nature.com, eating fecal material might prevent pathogens from killing you.

According to a study presented by Brett Finlay (University of British Columbia) at the International Human Microbiome Conference, mice that ingested particular kinds of poo were far more likely to survive exposure to gut pathogenic bacteria.  The experimental design was straightforward: one strain of mice was resistant and a second strain susceptible to Citrobacter rodentium (the pathogenic bacterium).  Dr. Finlay killed all the bacteria in the susceptible mice with antibiotics and then fed them feces from resistant mice.  The resistance was thereby transferred and most of the recipients survived.  The key appears to be that other bacteria living in the guts of resistant mice prevent the pathogen from doing damage.

While this approach is new, it nonetheless may not come as much surprise to the medical community. After all, they have been performing fecal transfusions for years.

What?  You've never had a fecal transfusion?

For some forms of colitis, medical practitioners will administer enemas of gut bacteria from the feces of close relatives to the patient.  A 2003 study published in the journal Clinical Infectious Diseases by Johannes Aas and colleagues found that most patients treated with donor stool survived diarrhea and colitis associated with the bacterium Clostridium difficile.  They further reported that "no adverse effects associated with stool treatment were observed."

That's good, because just reading about how the enemas were prepared using household blenders and coffee filters had an adverse effect on me.

And I think I will skip that bowl of Cocoa Puffs this morning.

To read more, visit Nature.com:

http://blogs.nature.com/cgi-bin/mt/mt-tb.cgi/12950