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Mankind, we’ll say, is at least a half million years old. It is very hard to understand how long a time half a million years really is. If we were to compare this whole length of time to one day, we’d get something like this: The present time is midnight, and Jesus was born just five minutes and thirty-six seconds ago. Earliest history began less than fifteen minutes ago. Everything before 11:45 was in prehistoric time.
Or maybe we can grasp the length of time better in terms of generations. As you know, primitive peoples tend to marry and have children rather early in life. So suppose we say that twenty years will make an average generation. At this rate there would be 25,000 generations in a half-million years. But our United States is much less than ten generations old, twenty-five generations take us back before the time of Columbus, Julius Caesar was alive just 100 generations ago, David was king of Israel less than 150 generations ago, 250 generations take us back to the beginning of written history. And there were 24,750 generations of men before written history began!
I should probably tell you that there is a new method of prehistoric dating which would cut the earliest dates in my reckoning almost in half. Dr. Cesare Emiliani, combining radioactive (C14) and chemical (oxygen isotope) methods in the study of deep-sea borings, has developed a system which would lower the total range of human prehistory to about 300,000 years. The system is still too new to have had general examination and testing. Hence, I have not used it in this book; it would mainly affect the dates earlier than 25,000 years ago.