Blacknad asks:
"How closely related?"

I can't provide a metric. Not my field of expertise but the profession considers them related.

Blacknad wrote:
"It is being said that guilt has an evolutionary function."

And it does. That which contributes to survival has value. That which doesn't is expendable. How does guilt contribute to survival? In social animals it is critical that one animal not alienate itself. No schooling fish can survive long without the school. Guilt, properly dialed in (not too much and not too little) keeps us from being kicked out of the school. Which is precisely what used to happen when people were excommunicated from the tribe to wander in the forest and die.

Blacknad wrote in response to my A2:
"Ah there must have been an evolutionary benefit.'"

I agree. But keep in mind science doesn't claim to have all of the answers to every question as of 6 July 2006. But so far all indications are that it does and their is no evidence to the contrary.

Blacknad wrote with respect to my A3:
"Gosh ? you Americans are such prudes ;-)"

Not me. My answer would be blunt and to the point. Which I don't think Kate and Rose would appreciate here at SAGG.

Blacknad wrote with respect to my A6:
"We don't see suicide in the animal kingdom ? it's unique to humans."

So is cooking our dinner on a stove. Individual cells commit suicide to protect the organism (apotosis). I don't see this as particularly troubling in terms of your original question.

Blacknad wrote:
"I think you are defending evolution ? but I am not attacking it."

Took me by surprise here.

Have you read "The Moral Animal" by Robert Wright. I definitely recommend it.
DA Morgan