Department of Sociology & Anthropology, North Carolina State University
Thursday All day, Plaza Level
Research concerning relative, or scale-free, limb proportions has revealed interesting patterns of variability with regards to environment. However, there have been no direct attempts to correlate variability in limb proportion with unrelated stress indicators. In response, this study examined the relationship between long bone length ratios and linear enamel hypoplasia (LEH) frequency in a modern Thai population.
Proximal/distal limb bone length ratios were calculated for 269 adults (105 female/154 male) and compared against LEH frequency. Analysis using Pearson’s correlation indicated significantly shorter relative distal limb lengths in the lower limbs of individuals with high LEH frequencies. This pattern was strongest in females, with statistically significant correlations in the tibia/femur (p=0.019) and the fibula/femur ratios (p=0.007) when compared with LEH frequencies, especially on the right side. LEH frequencies were also highly correlated with stature among females. In males, only the fibula/femur ratio demonstrated a significant relationship with LEH frequencies (p=0.008), and only on the left side of the body. No correlation between stature and LEH frequency was found in males, or between LEH frequency and long bone length proportions in the upper limbs of either sex.
These findings support claims that distal limb growth is more strongly affected by developmental stress than proximal growth. In this study, the upper and lower limbs demonstrate different responses to environmental stress. This disparity, in addition to the strong association of limb bone length ratios and LEH frequency in females, may have significant implications for our understanding of human limb development and catch-up growth.