Survival of the Fittest Meets Self-Sacrifice

I stumbled across something interesting in my Psychology textbook. (Yes, I'm taking Psychology, but only because it's a required class at my school. Believe it or not, it's actually incredibly eye opening to see how the world views things in terms of behavior and the mind... I could go on, but I'll get back to the subject.) The text was trying to explain why humans don't always act in a way that is most adaptive to their environment; why certain people sometimes sacrifice themselves so that the rest of the group can survive. Before the 50's, psychologists were stumped by this phenomenon. Why does a parent forego food and water so that their child can live? Why would a man jump in a river to save a drowning boy, risking his own life to rescue another? These ideas seemed almost incompatible with the idea of survival of the fittest because frankly, the actors wouldn't be benefiting themselves in that situation; they'd be putting themselves in harm's way. But then came the revelation that soothed all psychological qualms: "Sometimes actions that appear harmful to the individual can increase the chances that an adaptive gene will pass from one generation to the next. Moreover, it is now widely recognized that at least some of our actions are designed specifically to secure a mating partner and not necessarily to promote long term survival." (Psychology, by James Nairne) So that's that.
The problem is now solved in psychologists' minds. Or is it?

I don't know about you, but personally, their response was not exactly convincing. A mother starves herself for her child's chance at life to... pass an adaptive gene or secure a mating partner? I honestly can't believe that's what is going through her mind when she makes that decision.
The way I see it is this: no matter how you look at it, we were all created with an ability to discern right from wrong because we were designed by a Creator. We know what ought to be done. Although we're no longer perfect as we were originally created, we still have the ability to exercise traits that God instilled in us from the beginning, such as love, honor, and self-sacrifice. You can't explain it through evolution and survival of the fittest. The only explanation is that we have a self-sacrificing Creator who made us like Himself. Evolution has no basis for altruistic behavior because there is no God. But when God is in the picture, it makes all the sense in the world.