Age Structure V4

In the darkest blue, you can see the pyramid that represents the structure of the world population in 1950.

Two factors were responsible for the pyramid’s shape in 1950: an increasing number of births broadened the base layer of the population pyramid, and a high risk of death throughout life led to a narrowing towards the top. This means there were many newborns relative to the number of people at older ages.

The narrowing of the pyramid just above the base is testimony to the fact that child mortality used to be much higher in the past, with more than 1 in 5 children dying before the age of five in many low-income countries.

Through shades of blue and green the same visualization shows the population structure over the last decades up to 2018. You see that in each subsequent decade, the population pyramid was larger than before — in each decade more people of all ages were added to the world population.

If you look at the green pyramid for 2018 you see that the narrowing above the base is much less strong than back in 1950, as child mortality has fallen.

If you now compare the base of the pyramid in 2018 with the projection for 2100 you see that the coming decades will not resemble the past: According to the projections, there will be fewer children born at the end of this century than today. The base of the future population structure is narrower.

We are at a turning point in global population history. Between 1950 and today, it was a widening of the entire pyramid — an increase in the number of children — that was responsible for the increase in the world population.

From now on is not a widening of the base, but a ‘fill up’ of the population above the base: the number of children will barely increase and then start to decline, but the number of people of working age and old age will increase very substantially. As global health is improving and mortality is falling, the people alive today are expected to live longer than any generation before us.