on further thought i think our purpose is a much more basic and simple one. in affect we are very simular to ants but more complex, and our basic drive is for our needs = http://en.wikipedia.org/wiki/Maslow's_hierarchy_of_needs
which then leads us to collect and comunicate information, and then to find a partner and reproduce, then creating a good environment to bring up our young.
don't really think its more complicated than that really......
quite boring actually.....
damn..........