Introduction (cont.)

The basis of life tables has been dealt with in Module 1. A quite amazing early finding when studying demography is that the basic pattern of mortality is very similar for humans globally. That pattern is shown in Figure 1. Note that demographers invariably plot the y axis as a log scale since this shows greater detail at younger ages.

Figure 1. The common pattern of human mortality
Risk of death (_nq_x on log scale) by age for three different levels and patterns of mortality

The pattern is typically one of high mortality risk at the time of birth which then falls rapidly but steadily until ages 8-13, then rises during teenage years to a plateau in the early 20’s (but usually still at lower risk than at birth), then begins a slow rise in risk which accelerates as age increases, overtaking the risk at birth around middle-age and continuing to rise until the oldest known ages. The rate of increase in risk often slows at old ages, but never actually declines.

There are some regular differences between males and females, and some notable small features across the age range but basically the pattern is similar for all humans.