Selflessness

I am pretty sure I've stated before my believe in cause and reaction and how everything is intwined in some way, however obscure it may be. And recently I've been wondering if there really is such a thing as a truly selfless act.

Now what is meant by a selfless act. According to wikipedia it is the sacrifice of ones own interests for the greater good.

But surely the greater good is in everyone interest. As a race we are genetically programmed to preserve the race at any cost, therefore any act we do is purely for our own interest however subconscious it be.

Lets take an extreme example, you want to buy a cake but on your way you see a child about to get hit by a car, you know the cake will be sold out if you help the child. Of course the child would be anyones top priority. But is that only because we are told that is right.

Basic animal kingdom rule of survival of the fittest, a young can't fed for themselves of course you are going to leave them be and get food.

Where does selflessness come into play with our race that has clearly been distinctively growing in attribute to situations, eg determination to strive for better things to always be the better thing. Are such attributes such things just part of us that wish to carry on and a grit to succeed. Are they purely from our animal ancestors, it may seem so.

But if so where does selflessness come from unless it isn't selfless but an act which along with compassion somewhat flaws the rule. Which means we have gone through an emotional evolution, and if so how did this happen. Or selflessness has some sort of survival trick behind it.

Is there such thing as being nice for the sake of being nice or do again the unknown chemicals that make us do everyday things passing messages that we, along with the world take to mean something however our animal brains behind us have darker more selfish intentions.