I have been thinking lately about the idea of a 'purpose' in life. I'm not sure if the humans of prehistory saw a purpose to their existance, or if they even needed one. It is generally true that struggling for survival is a purpose in itsself — those in the worst situations don't generally suffer from melancholy depression, that's a luxury of the safe. Even after humans progressed to the point where life was not a daily struggle for survival (at least not for everyone), religion served to give people a purpose. In the European middle ages, you were meant to do what your family had done in 'time immemorial', and God was pleased with that. The death (or at least dillution) of religion and the 'global community', in which it is socially unacceptable to blindly hate another group, have taken away some of the 'greater purpose' in life. Also, capitalism and democracy have given people the freedom to do whatever they choose — but it has also made them wholly responsible for their situations. A peasant in the middle ages was, at least in theory, a respected member of society. They were fulfilling their life's purpose, and no one expected more of them. Now life is up to each of us, and failure to move upward is a failing in ourselves.
It is certainly not that democracy, capitalism, or rationality are bad — they have improved the lives of everyone on earth. It is just that humans still want to feel that they are fulfilling some purpose, and in our existential society it is hard to find that purpose. It is interesting to note the new (and not so new) research showing how much of our personality is genetically determined, though. If this 'predetermination' becomes accepted fact, it will be a much different society. Everyone will have a 'place' in life again, and perhaps respect will be given back to the modern peasants.