As far as we can tell, evolution does not have a purpose. It is like a rock rolling down a slope. It may seem like it has a goal — to get to the bottom of the slope, or to crush a particular something on its way down — but those are just things that happen by the by. All that is happening is that a rock is rolling down a mountain.
The only way we can honestly answer this question is with the help of what we know. The rock exists, the mountain exists, gravity exists. That’s all. There is no deeper meaning than that. We can make stuff up and tell stories about where the rock came from, who rolled it down, and why, but that’s all they are — stories and conjecture.
The question about human purpose therefore, may also seem meaningless. After all, in the larger scheme of things, we are as insignificant as slimy germs that grow on the aforementioned rock, why bother with anything? Why not just die?
We don’t know this for sure, but it does not seem like any species — animal or plant — other than us bothers with meaning. They just live and die. It is only the human species that bothers with all this fancy philosophical wonderment.
This fancy philosophical wonderment however, has been the source of all religion. Through it, and because we have this need to find purpose, we have convinced ourselves that purpose exists. We have, in effect, made up stories to help fulfill our desperate need for purpose.
These stories have told us that not only does purpose exist, it is divine purpose, ultimate purpose, even cosmic purpose. Through the ages, our convictions and beliefs have led us down various paths in pursuit of this purpose. Some of us are convinced for example, that our purpose is to serve god’s will and to make him happy. Others are convinced that their purpose is to kill and destroy every member of their species who does not agree with them. Some others are convinced that our purpose is to take care of this world and make sure no harm comes to it.
All these reasons of course, are man-made. These are things we made up because we can’t stand being purposeless. The thought that we exist for no reason drives us crazy. I feel that the entire history of human civilisation can be described in terms of a quest to escape this pit of madness.
This is why every way of thinking that goes against the currently accepted purpose-philosophies is treated with hostility. This is why religious ones freak out when you suggest there is no god — who will they please if there is no god? This is why people wedded to a particular political philosophy lose their shit when you suggest their way may be pointless — what are they supposed to do if there way is not the one true way? Purposelessness is madness and death to a human being. It is hell.
In such a scenario, a human being chooses purpose. He chooses to belong to a story of his choice — one that makes most sense to him, makes him happy, gives him something to look forward to. He may choose from among already-existing options and become a member of a religion or ideology. Most people choose the ones they are close to — the religion they were born into or the ideology their parents live by. Others choose to break free and go see what’s on the other side of the fence. Still others make up their own philosophies and live unique lives.
At the end of the day, there is no “supposed to”. Human beings do what they can do with what they have. And what they have is an understanding of their place in the universe. This understanding tells us that in some respects we are not special and that in some other respects we are indeed unique. We can expand our understanding of the world using the scientific method. We can communicate this understanding to each other using language and storytelling. And lastly, we can put this understanding to practical use and make the lives of each other and our descendants a little easier. What else is there to do?