Stature estimations are an important part of investigating health and status in the past. Individuals with poor health throughout their growth period will not grow to their full potential. Bioarchaeology studies have often used height as a way to track changes in health over time. As health improves in the overall community, the average height will go up. However, this relationship is not always straightforward and is subject to a number of potential problems. First, the interaction of heredity and environment is not completely known. Second, the statistical equations for determining stature can be flawed. Finally, the social context needs to be examined carefully before drawing any conclusions (migration, etc). In a new study by Vercellotti et al. (2011), variation of stature within a skeletal population is examined in order to determine whether there is a clear correlation of height and status. Specifically they examine body proportions to see the variation of insult to specific skeletal elements and the relationship with social class. They calculate the body variations of 52 individuals from a medieval Italian cemetery, including 6 high status females, 14 high status males, 14 low status females and 16 low status males. The status was determined by grave goods and location in the cemetery.
The expression of human body size is based on an interaction between genetic predisposition and environmental context. Even within populations with low genetic diversity, there is intrapopulation variation of height. These differences arise primarily from the environment, and the duration and timing of the interaction. The timing of growth varies through sub-adulthood, with different segments of bones growing at different times in life. Environmental factors to consider include subsistence strategies, access to resources, social organization, sanitary conditions, climate and activity levels. Primarily it comes down to nutrition and disease. In order to grow properly, bones require a number of different minerals and vitamins, including calcium, phosphorous, and vitamin D. Poor growth may be due to a diet that is lacking in nutrients, or lack of access to vitamin rich resources due to social status or other factors. If the living conditions of the individuals are unsanitary they may be more prone to disease or infection, which can leech minerals and vitamins from bones. Climate is especially important for intake of vitamin D- without access to sunlight or because of living in a sun light deprived area, individuals have difficulty getting vitamin D. All of these are important to consider when looking at stature.
Determining stature is done by through a number of methods when using skeletal remains. One potential method is measuring all skeletal elements, which are included in the height of an individual while taking into account soft tissue that may add height. The problem with using this method is that it requires a complete skeleton as well as a good approximation on age in order to estimate the heights of the soft tissues. The more common method is using single long bones and a statistical regression formula to determine height. These formulae are based on previously measured and known stature skeletal collections. There are a number of these that can be used for comparison. Researchers only need to determine which population is closest ethnically and use it to determine height in their population. In order to properly determine height averages, the population also needs to be divided by age and sex, both of which have a major effect on the stature of the individual. Body size can also be determined by looking at the morphological properties of the long bones, especially femoral head. In order to calculate the heights of their medieval population, Vercellotti et al. (2011) use the long bones to calculate body mass, and use all living stature bones to determine stature. They found that high status males had a higher mass than low status males, but no significant difference between females. Also in males, the lower limbs were often longer in high status individuals.
Explaining this difference, Vercellotti et al. (2011) consider environmental and social factors. First, they argue that the difference in the males suggests that there was more variation in the way that males are treated, especially during the period when lower long bone growth was occurring. Second, they argue that this may be due to patriarchy of medieval Italy. High status males may have been the only ones who were able to get the best resources, and therefore reached their highest growth potential versus all others. It is known during this period that high status males were able to get protein more than other groups, and it is therefore likely they also got access to other high nutrient foods. Finally, Vercellotti et al. (2011) note that there may be bias in these results for a number of reasons including the small sample, the potential that females may be less susceptible to environment affecting their height, or problems with the statistics.
Overall, this careful look at the use of stature is refreshing when many often use stature without closely looking at all the possible factors that affect it. Vercellotti et al. (2011) do a thorough job of carefully assessing a range of evidence. If you are going to be doing stature analysis, this is a good example of a careful way to approach it. The only downside is that they don’t explore the historical context as completely as they could have.
Vercellotti G, Stout SD, Boano R, & Sciulli PW (2011). Intrapopulation variation in stature and body proportions: social status and sex differences in an Italian medieval population (Trino Vercellese, VC). American journal of physical anthropology, 145 (2), 203-14 PMID: 21312185