MadSci Network: General Biology

Re: Is it possible to create a makeshift life-raft out of human corpses?

Date: Mon Oct 31 08:50:13 2005
Posted By: Tye Morancy, Staff, Medical Physicist/Dosimetrist, Beth Israel Deaconess Medical Center
Area of science: General Biology
ID: 1129691949.Gb

Hello Erica,

Thank you for the question...seems ironic that I would answer this on 

I think I heard of this scene in some conversation somewhere from the 
show "Rome", right?  First, I don't think I have ever heard of this.  It 
seems this would be something very rare to occur, considering the nature 
of being in a situation where you are struggling for survival, have no 
ballast available, and conceive of the need to go to this extreme.  I 
read somewhere that in ancient Rome sailors feared death at sea, since 
their body would not be buried in the ground, instead floating on the 
water, possibly leaving them to wander the river Styx for a hundred years 
before being allowed to enter the land of the dead.

Ok, on to the science...

Would corpses be effective in such a dire situation to stay afloat?  
Yes.  It is a matter of how many you are using, the nature of how they 
died, and how many people you were trying to put on this scary 
raft...Obviously if someone died or was killed with the body intact and 
not full of water (possibly by drowning), the body acts like pontoon with 
some buoyancy (although not a whole lot...).  Rather than try to explain 
a lot of examples, I thought it best to give you some information on 
factors that make them float:  

Lungs: Lungs are like a sponge. When someone drowns, the air sacs in the 
lungs fill with water. Since a body without air in the lungs is denser 
than water, it sinks. A person who is killed on the surface and then put 
in the water tends to float, since the lungs are still full of air.  

Body Position: A person who was dead before entering the water can still 
sink depending on the position of the body.  If the body is upright when 
dumped into the water, water can enter the lungs while air escapes. 
Hence, the body sinks after a short time. If the body is prone (face 
down), the air in the lungs can't escape, so the body floats. 

Body Fat: Body fat is less dense than water. The fatter a person is, the 
more buoyant the body. Muscle on the other hand is denser than water, so 
people with a lot of muscle--or people who are just plain lean--tend to 

Clothing: Some fabrics trap air well; others don't. Natural fibers, like 
cotton and wool, absorb water and so tend to sink. An exception is silk, 
whose fine fibers can be woven tightly enough to trap air. In more modern 
times, some synthetic fibers, like nylon and polyester, usually don't 
absorb water, so they can trap air.  

Putrefaction: As the corpse decays, it generates gases that collect in 
various body cavities. That's why corpses become bloated, whether in the 
water or not, giving us the charming term "floater." 

The water can also affect buoyancy: 

Salinity: Probably the most important factor is salinity. Salt water is 
denser than fresh water, so corpses tend to float in the ocean but not in 
a river. 

Temperature: The water's temperature affects its density. Water is 
densest at 4 degrees Celsius (about 39 degrees Fahrenheit). Bodies of 
water often have a thermocline (a depth where there's a dramatic change 
in temperature). Warm waters "float" and circulate by convection when 
warmed by the sun; colder waters "sink" and tend to stay there. Hence, 
there is a slight (very slight) tendency for bodies in cold water to 
float, since they may be less dense than the water surrounding them. 

You asked the question as to what happens to a body in the water, 
regarding rotting or being scavenged by the ocean's inhabitants.   

Bodies exposed to water decompose approximately four times faster than in 
earth, and if the water is warm or polluted, this occurs much faster.  

Insects also get into the act. Bodies that float near land for even a few 
minutes will have maggot infestations in all body cavities. Aquatic 
insects may also feed on the body, but these insects seem to accidentally 
happen onto the body rather than being attracted by the odor. (Forensic 
scientists are investigating whether aquatic insects can be used to 
estimate the time a body was immersed in water). 

If a body rests in water for only a short time, especially if the water 
is cold and contains minimal fish life, a variety of changes can occur. 
The skin of the palms and soles intially becomes very wrinkled, 
called "washerwoman skin" by pathologists, looking similar to a person's 
hands and feet after spending too much time in a swimming pool or 
bathtub. If the body is submerged in cool (less than 70F or 21C) to cold 
(less than 40F or 4,4C) water for as little as one to three weeks, the 
corpse's tissues convert to adipocere, a compound that stops the activity 
of bacteria. The preservation from cold water was exemplified by two 
bodies trapped for five years in a car that sank in Lake Superior outside 
of duluth, Minnesota. The very cold water produced extensive adipocere 
formation and well-preserved internal organs. 

After bieng in water for hours to days, a corpse's skin becomes white, 
soft, and extremely unpleasant to sight and smell. In warmer water, the 
decomposition advances rapidly, with the skin quickly loosening, 
darkening and becoming stained with blood. 

If fish are present to help consume the body, decomposition accelerates a 
hundred-fold. Fish, crabs and small marine animals quickly begin to feed 
on the soft parts of a corpse's face. the eyelids, lips and ears are the 
first to go, and then the eyes, nose and mouth.  In some areas of the 
sea, large fish are scarce, so it is the smaller animal life that feeds 
on the remains. These small creatures, however, are quite efficient. 
Larger animals feed on the torso and extremities.

So with all this said, it does seem plausible to be able to make a raft 
as they did in this portrayal.

I would also direct you to a book I have read, called "Stiff: The Curious 
Lives of Human Cadavers ", which documents svereal ways in which cadavers 
are used in the name of scientific research, across several 
applications.  The reason this came to mind was one of the chapters which 
deals in forensic description of how a human body decomposes in a natural 
setting, albeit on land, but still explains some of the processes which 
may further explain to you why they float as they do.  

I hope this answered your questions.  Let us know if any new ones were 
spurred from this discussion...


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