biologists, neurologists, ... about morality. when it comes to guilt, they don't have an answer. but maybe can tell you more ... i was already on my way home; together with some exhausted philosophers eméritos in the metro.

there is one spanish neurologist i actually want to meet: he has opened up a restaurant and cooks there at night. during the day he counts neurons, i estimate.

During the talk Mariann and I were, Premack said something interesting about science methodology: that you have to make justice to the phenomenon you are interestes in. Premack was talking about emotions and how neurologist do not really make justice to the complexity of the phenomenon.
I believe that biology oriented cognitve scientist do the same with moral phenomena. They like to talk about "selfish genes" and mother's love for their children as rewarded by evolution and so on, but they don't really pay attention to the complexity of moral emotions.
Guilt is a good test on that. Guilt is one of the major moral emotions. To feel guilt you need to be:
a) self -conscious
b) have a representation of yourself as a moral agent. Someone that is aware of the consequences of his/her own actions
c) an internalized moral code that tells you what is right and what is wrong

I am not saying that guilt can not be explained biologically. But I believe that it cannot be devaluated into a simple Darwinian explanation about selfish genes and the release of hormones.