Why is, um, fecal matter brown?
The other day, a friend of mine asked me a question which left me speechless. I could not begin to come up with an answer. You are my only hope. Why is [fecal matter] brown?
I am not answering this question, friends and neighbors, out of any low motives. I merely wish to demonstrate that there is an answer for everything, if we but apply ourselves to the problem.
The thing that makes (ahem) fecal matter brown is a potent brownish-yellow pigment called bilirubin, which is found in the bile. It's what is left over when red blood cells die off and decompose, as they normally do throughout your life.
Bilirubin is taken out of the blood by the liver. There it's concentrated and shunted around some until it winds up in the intestines and gets excreted.
Isn't that interesting? Wouldn't it be a great way to liven up dinner at Mom's next week? You want to be a more fascinating conversationalist, you just keep reading the Straight Dope.