Who is this "we"? And what have we figured out exactly?
"We"? Social anthropologists, sociologists, behaviorists, philosophers, evolutionary psychologists, etc (we is loosely defined to mean group conscious).
"Exactly"? I'm not sure how much has been figured out exactly. To the extent that any thing has I hardly have the time or wherewithal to tell you exactly. You say you are a "philosophy student" perhaps I read too much into that. I have a bit of a difficult time reconciling that statement with your question. In the interest of time can you tell me what it means to you to be a "philosophy student"?
Are you familiar with Friedrich Nietzsche? Emanuel Kant? Peter Singer? B.F. Skinner? John Watson? (to name but a few and no, not all philosophers.) Do you know the difference between utilitarianism and the categorical imperative.
Forgive me for being presumptuous and assuming that you are unfamiliar with the scientific breadth of our understanding of morals based on your question and would like to learn more. If so then let me make some recommendations. Since you like Shermer I would recommend
The Science of Good and Evil. I would also highly recommend Darwin's
The Expression of the Emotions in Man and Animals. We've come a long way since but it is amazing how well so many of Darwin's ideas have passed the test of time. I have just recently received Daniel Dennett's
Darwin's Dangerous Idea and have not read it but based on the reviews it looks promising and Dennett has recently become one of my favorite philosophers. I'm currently reading Nietzsche's Antichrist and thoroughly enjoying it so I plan to order Beyond Good and Evil so you might want to add that to your list.
If I have been too presumptuous and you are familiar with much or most of the work and history of morality then please accept my apology and get me up to speed with your current understanding and I will try and answer your question.
Thanks,
RandFan