Poor nutrition and illness in childhood limit human growth. As a consequence, the average height of a population is strongly correlated with living standards in a population. This makes the study of human height relevant for historians who want to understand the history of living conditions.
Because the effect of better material living standards is to make people taller, human height is used as an indirect measure of living standards. It is especially relevant for the study of living conditions in periods for which little or no other data is available — what historians refer to as the pre-statistical period.
It is important to stress that height is not used as a direct measure of well-being. The variation of height within a given population is largely determined by genetic factors.1
The history of human height allows us to track progress against undernourishment and disease and makes it possible to understand who started to benefit from modern advancements and when.
Source and more detailed information: https://ourworldindata.org/human-height