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| Source: thefeministbreeder.com |
While nearly every mammal consumes its placenta after giving
birth (a notable exception being marsupials who instead reabsorb the placenta,
but do consume birth fluids), research has yet to conclusively find one
overarching reason for placentophagia in mammals. Currently, four theories are used to explain
this seemingly innate mammalian behavior.
The first is that during birth, the mother, normally an herbivore,
suddenly becomes carnivorous, only craving meat. As someone who has previously given birth and
has been a vegetarian for the past 12 years, I personally found this theory
unlikely as I had no desire to eat meat following the birth of my first child, even
when hospital’s dining facility continually ignored my vegetarian requests and
primarily served me meat. Like the
rodents in studies that investigate this hypothesis, I still refused the meat!
A second theory is that the
mother simply craves food after following birth. While any mother can attest to the fact that
birth is certainly a physical feat that requires recovery, placentophagia has
been observed in mammals that continue to eat throughout labor and delivery
who, presumably, would not have an increase in hunger following the event. The third theory again focuses on hunger, but
this theory looks at a specific hunger for the placenta. Research on this theory has been inconclusive
as mammals that have not yet given birth will consume another animal’s
placenta.
The
final and perhaps most popular theory is that placentophagia is simply a way
for mammals to maintain a clean nest in order to prevent the attraction of
predators. While this theory is
straight-forward, it does ignore several refuting factors. Firstly, as previously stated, nearly every
mammal consumes its placenta. This means
that even the mightiest of predators, which are in little need to detract other
mammals, takes the time to eat their placentas.
Secondly, animals who do not maintain a constant nesting site remain at
the site of the birth to consume the placenta, actually putting themselves in
greater risk of predators. A final
challenge to the nest theory, and the one I found most convincing, is the fact
the placenta is not the only bodily expulsion during labor. Blood and other amniotic fluids would also
completely saturate the area, clearly leaving evidence of a nest, despite the
removal of the placenta.
Each of these theories clearly has it's skeptics- check out next week's post to learn more evolutionary (and, in my mind, convincing) rationales!
Source:
Kristal, M.B. (1980). Placentophagia: A biobehavioral enigma. Neuroscience and Biohehavioral Reviews, (4)141-150.
Source:
Kristal, M.B. (1980). Placentophagia: A biobehavioral enigma. Neuroscience and Biohehavioral Reviews, (4)141-150.
