Pilgrims traveled to Rome this week to view the body of Pope John Paul II, who died last Saturday. Vatican officials say the body has not been embalmed but only "prepared" for viewing. How long will it take for the pope to decompose? And why wasn't he embalmed in the first place?
Barring unusual conditions, putrefaction usually sets in within about a week. At that stage of decomposition, bacteria from the intestines start breaking down body tissues and releasing foul-smelling gases and fluids. Pressure within the body causes abdominal bloating and the "purge" of fluids through the nose and mouth.
The speed at which a body decomposes depends on a number of factors, including temperature and body type. As a general rule, the bodies of fat people in a hot and humid environment will rot more quickly than those of skinny people in cooler weather. The temperature in Rome this week has been in the low 60s, but it's likely colder within the stone walls of St. Peter's. On the other hand, the thousands of people filing through the Basilica have probably generated a fair bit of heat. Decomposition could be staved off by refrigeration, but the pope's body appears to be lying on an uncovered catafalque.
There has been intense speculation about the state of the pope's body among American death industry professionals. Some claim to have identified a purpling of the lips in photographs, suggestive of decay produced by bacterial populations in the mouth and on the gums. Others say the pope shows signs of bloating.
There seems to be no strict Vatican policy on how the pope's body should be preserved. Most recent popes have been embalmed, including the last four before John Paul II: Pius XII, John XXIII, Paul VI, and John Paul I. While he didn't say anything specific about embalming in his testament, John Paul II did state that he wanted to be buried "in the bare earth, not a tomb."
The unembalmed body of John Paul II may have been partially preserved without being subjected to the whole process. A full-scale embalming (which is most common in the United States, New Zealand, and Australia) takes several steps. The embalmer first disinfects the outside of the body, then inserts tubes into a major artery and a major vein. Next, he pumps a mixture of fixatives, dyes, and perfume into the artery using an "embalming machine" and flushes blood and other fluids out through the open vein. Finally, he sucks gases and liquids out of the abdominal and chest cavities through a long tube and replaces them with more fixative. The pope's body did not go through all these steps, but it's possible that his corpse was treated only in the cavities or partially fixed with surface injections.
John Paul II will not be the first pope to decompose in public. In August of 1978, the body of Paul VI "took on a greenish tinge," and fans were installed in the Basilica to disperse the smell. Twenty years earlier, a maverick doctor persuaded the Vatican to let him try an experimental embalming technique on the body of Pope Pius XII, with disastrous consequences—the body turned black and disintegrated in the casket. Pope John XXIII, who died in 1963, seems to have been treated better: When his embalmed body was disinterred in 2001, it looked to be in pretty good shape.
If John Paul II is eventually canonized, he might not have to worry. Some Catholics believe that the bodies of saints are "incorruptible." That is, they never decompose.
Explainer thanks Lawrence Cunningham of the University of Notre Dame, John Dodge of the Dodge Company, and David Tackett of the Cincinnati College of Mortuary Science.