Seriously though, I’m not sure if science can answer this sort of question. Science tends to tell us how things happen, or what physical or otherwise measurable things causes things to happen, not why they happen. For example, the Big Bang explains how the Universe began, but not why. It’s a very good question though.
Hehe this might be the ultimate science project – everyone has to find their answer to this question and it usually takes at least a lifetime of experiments. My current view is: Life doesn’t have to have a meaning, in the same way that a beautiful piece of music doesn’t have to have a meaning or a purpose. It’s beautiful and that is enough. Listen to it as hard as you can.
I think science can tell us why we are here in the sense of how we came to be here (the big bang, evolution, all those lovely things). As for ‘to what purpose are we here?’… Well, if life is a piece of music, someone’s gotta listen to it, right? I don’t think that we were necessarily designed for this purpose, but it’s a great purpose to have in your life.