A comparative study of the occurrence of transverse readiopaque lines in archaic, early modern, and holocene human population

Transverse radiopaque lines, often referred to as transverse lines (TL\u27s), are a type of hard-tissue pathology which develop in subadult long bones after episodes of nonspecific stress such as nutritional or metabolic insult. This pathology is well documented in archaeological contexts and is used as a tool for making paleo demographical inferences about the general health of populations. Stable isotope studies have suggested that early modern humans were exploiting a wide range of dietary resources by the mid-Upper Paleolithic, while Neandertals appear to have utilized a narrower spectrum of resources, expending more energy on large game. This may have been a significant factor in differential survival success, frequency of transverse line formation, and age of initial transverse line formation. Because archaic humans may have been more susceptible to seasonal resource fluctuations, they may have suffered increased nutritional and metabolic stress compared to early modern humans. This study evaluates differences in the frequency and timing of initial transverse line formation among archaic, early modern human, and recent human (Holocene) subadult populations. Radiographs of the tibial distal shafts of 200 archaic, early modern humans, and recent modern humans were scored as displaying or not displaying TL\u27s. TL\u27s were counted, and age-at-formation was calculated. Kruskal-Wallis nonparametric tests were used to compare the frequency of occurrence of TL\u27s and age-at-formation among the three groups. Results indicate that both archaic and early modern humans exhibited less transverse lines than the recent human group. This may be related to sampling bias in the recent human dataset. There is no difference in the number of transverse lines among the recent human samples, and it seems possible that all three of the recent human populations sampled for this study were experiencing high levels of stress. Thus, it seems that for the archaic and early modern human groups, transverse line formation may have been more closely related to differences in subsistence strategies, while transverse line formation in the recent human group may have been more closely related to high frequencies of metabolic diseases and poor diet. Further analysis revealed that archaic humans developed their first transverse lines earlier in life than both early modern and recent modern humans. The age at first line formation is frequently related to weaning age in studies of archaeological population, and this (and other possible explanations) are evaluated relative to Late Pleistocene Neanderthals and early modern humans