When they come to record the history of our own times, future historians will be able to have the great mass of evidence relied on. The great amount of evidence includes not only the written word, but also electronic equipment such as films, videos, CDs and CD-ROMs. But the historian attempting to reconstruct the distant past has to deduce from the few scanty clues available. Even seemingly insignificant remains can shed light on the history of early man. Up to now, historian have assumed that calenders came into being with the advent of agriculture, for then man was faced with a real need to undstand something about the seasons. The nomads lived by hunting and fishing during the last Ice Age which began about 35,000 B.C. and ended about 10,000 B.C. And the markings engraved on walls, bones and the ivory tusks of mammoths by the nomads have been proved to be connected with the passage of days and the phases of the moon. It is, in fact, a primitive type of calender. It seems that man was making a real effort to understand the seasons 20,000 years earlier than has been supposed.
