In the previous chapter, we showed how we can construct a rough approximation of the social network from the number of people in a society. In this chapter, we will explore how human lives influence history. We are interested in the fact that for most events, no survivors are left to tell the narrative first-hand after roughly 70 years. Those who do survive are old, frail, and possibly unreliable. Therefore, there is a big difference between short-term history—a history where witnesses are still alive—and a history where all witnesses are dead, and we can no longer ask for a first-hand account of the events, see Fig. 9.1.