We are constantly reminded of the small amount of time it has taken for human beings to move from the Stone Age to modernity. In some ways a certain agnosticism seems preferable here to the gee whizzes of popular science. How long should it take an intelligent tool-making species to move from the wheel to the jet engine? Is it really so very amazing that while bacterial life started on earth more than three billion years ago, land plants apparently date from a mere 400 million years ago, shortly after the first fish and about the same time as the first amphibia? What, in any case, is the significance of talk of vast tracts of time in the absence of creatures that can plan, reflect on what they are doing, and come to an awareness of the passing of time, and hence of tasks accomplished fast or slowly? .

             As a mater of fact, the theory helps justify the existence of human minds because what is more significant than the mere passage of time, whether this is long or short, are the transitions in emphasis in human culture from activities which are directed to survival and reproduction to those which are not. Hunting and gathering, eating, sleeping, reproducing and caring for the young are activities without which neither individuals nor species would survive. They also take up an awful lot of time, particularly if you do not know how to cook, plant seeds, domesticate animals, or organize your economy on the basis of specialization and the division of labor. If you are having to spend most of your day simply surviving and providing for your dependants, you are not going to find much time for developing the higher activities of art, science, morality, and religion, even if (as I believe is the case) there are in reflective, self-conscious beings drives in each of these directions, however simple or sophisticated their economies. .

             By around 10,000 BC mankind had learned to farm and in a few places was beginning to live in towns.