Stripped to the barest roots, you could say I served my evolutionary purpose by reproducing--three times, in fact. Beyond that, I have a responsibility to ensure my offspring survive to adulthood and have the means to survive after I'm no longer caring for them. So is that it? The purpose of life is to make babies and raise them? While many--myself included--find fulfillment in parenting, it doesn't make sense to me for that to be the be-all, end-all. Do people who have no children, by choice or by circumstance, serve no purpose? I simply can't believe that.
The key lies in the one thing that separates human beings from every other species that we know of--our intelligence. The most amazing thing evolution has ever achieved is producing a species intelligent enough to overcome the physical limitations of evolution. Sure, fur might keep some animals warm during the winter, but having the brains to start a fire or build a house or develop the technology for central heating is much more adaptable, capable of solving many more problems than just being cold. We've evolved to the point now that we are no longer limited by the survival of the fittest; we have the means to keep all of our species alive, including the weakest. This is actually an evolutionary advantage, because the traits that are valuable to our species' survival today may not be the same traits we need to survive tomorrow. Diversity is strength.
So on a macro scale, we contribute to the survival of the species through advancements in science and technology. On a micro scale, each of us has a purpose, even if we aren't Einsteins or Newtons. The thing about intelligence is that with it comes self-awareness. We are smart enough not only to survive, but to ask whether we want to survive. The only way the human race will continue surviving is if we have motivation to do so. In short, it's our job to make life worth living. I can do this for others by finding ways to make their lives happier, more meaningful. It's equally important that I find ways to make my own life happier and more meaningful.
Evolution's dictates, then, are (1) be happy, and (2) help other people be happy. Maybe you've come to a similar conclusion via religion, but for me it comes down to doing what my genes programmed me to do. That is my purpose. That is my meaning. Evolution is all the religion I need.