Why do we find things disgusting (e.g. feces, blood, etc.)?

Dear top19-ga,

From my research it appears that surprisingly little research had been
conducted on this subject. The reason for our disgust of such things
has been a source of speculation, and the answer is not yet known.
Some argue that it is a by-product of the way we live, or it could be
the way we are brought up: nature and nurture, others say that it is
evolutionary and an instinct to survive.

On these pages the proponents of these three main idea are set out:
Curtis, Douglas and Rozin.
Channel 4 discussion of Disgust
http://www.channel4.com/culture/microsites/A/anatomy_disgust/intro.html
http://www.channel4.com/culture/microsites/A/anatomy_disgust/science.html#rozin
http://www.channel4.com/culture/microsites/A/anatomy_disgust/curtis.html
http://www.channel4.com/culture/microsites/A/anatomy_disgust/douglas.html

These are some pages by Drs Val Curtis, Dr Robert Aunger and Dr Tamer
Rabie from the London School of Hygiene and Tropical Medicine. You may
find that the following pages useful and again will give you some of
the various explanations that are currently put forward.

Dirt, disgust and disease: is hygiene in our genes?
http://www.lshtm.ac.uk/dcvbu/staff/dirt_article.htm

Survey shows disgust emotion evolved to safeguard humans from disease
and secure adaptive advantage
http://www.lshtm.ac.uk/news/2004/disgustfactor.html


This article on Discovery gives further information.
The Biology of . . . Disgust
?Psychiatrist Mary Phillips at the Institute of Psychiatry in London
and neuropsychologist Andy Calder of Cambridge University have found
that disgust has its own department in the brain, one separate from
that used to process fear. Using magnetic resonance imaging, they
found that two regions of the brain light up when subjects view either
facial expressions of disgust or disgusting scenes such as cockroaches
or decaying meat. One is the striatum, which is involved in movement,
cognition, and reward. The other is the insula, which plays a key role
in our ability to taste.?
 http://www.discover.com/issues/dec-02/departments/featbiology/

Food for Thought:
Paul Rozin's Research and Teaching at Penn
http://www.sas.upenn.edu/sasalum/newsltr/fall97/rozin.html
http://192.68.112.205/bcnow/story.asp?ArticleID=662

Purity and Danger: An Analysis of the Concepts of Pollution and Taboo (Paperback)
by Mary Douglas "
http://www.amazon.com/Purity-Danger-Analysis-Concepts-Pollution/dp/0415289955


I hope this answers your question. If it does not, or the answer is
unclear, then please ask for clarification of this research before
rating the answer. I shall respond to the clarification request as
soon as I receive it.
Thank you
answerfinder

Search strategy
disgust vomit faeces , led me to Curtis?s pges and then followed
various links and bibliographies.

The toast of google answers.

Speak for yourself!

Dogs love rolling in cow dung.

One man's meat ....

Just by coincidence, my German newspaper has today a one page article
on the subject of disgusting foods  - as background for a scandal
about overdue meat being relabeled and sold.  Of course, this does not
include faeces, except maybe those of mites and maggots.

A few examples:
Swedish canned herring that isn't considered ripe to eat until the can
is threatening to explode (with instructions for opening the can);
German (Sachsen-Anhalt) "Würchwitzer Millnkäs", a cheese that is
allowed to ripen until the surface is covered with mites (Picture, but
no instructions for eating);
Faeroe Islands:  shark buried for weeks (summer) or months (winter) in
gravel, giving off a latrine odor, then hung to dry for two months,
when it has a "cheesy taste, to express it politely";
Philippines:  a form of salted pork that is kept until the first
maggots show their heads;
Sardinia:  "Casu Marzu", a cheese that is stored until the maggots
start to jump, at which time the very sharp tasting, greasy cheese is
considered ripe to eat.  "More sensitive persons shake off the
maggots, but the sturdy Sards eat them with their cheese."

And, of course, the Tutsis drink the blood of their cattle;,
Australian Aborigines eat grubs; some places in Asia, people eat
larger insects, deep fried, and raw brain of lamb and monkey.

Disgusting enough?  The article points out that disgust is mainly
cultural; that an ahborance to things becomes conditioned between the
ages of 5 and 7.
  (This may have something to do with why some European refuse to eat
certain types of American fastfood.)

Oh, I forgot Probono's comment:  that may be why the dog cadavers one
finds in food markets in China have all the hair singed off.

Don't forget all the Western ones that are also disgusting...
black pudding
haggis
rocky mountain oysters
head cheese
tongue
escargo

Quite so, Frank, and a nice demonstration of the cultural aspect. 
Strangely enough, I have eaten all of those  - without disgust.  Well,
it was sheep's "oysters" once in Iran.

One man's fish is another man's poisson.