Adult age at death estimation: methods tested on Thai postcranial skeletal remains

Scientific literature frequently reports that age-at-death estimation standards developed on European and North American populations are less effective when used on genetically distant populations. Ultimately, this paper aims to inform forensic anthropologists and bioarchaeologists of the most appropriate methods to use on Southeast Asian skeletal remains by evaluating studies that have tested the replicability and accuracy of adult age estimation methods on Thai target samples. Results show that methods using the pelvis recorded the highest accuracy of up to 93%, but only when broad age ranges are used (+/- 2 SD). Most methods produced the least bias and inaccuracy in young adults but considerably underaged older adults. Overall biases and inaccuracies tended to be lower for males than females. The sternal rib end method showed the weakest correlation with chronological age. Methods that produced age prediction equations developed with regression analyses derived from the Thai samples produced standard errors ranging from 9.5 to 13.9 years (using vertebrae and femora). Most of these methods were deemed too imprecise to be useful in Thai forensic cases. The best way forward to understand the wide range of morphological variation is for future studies to evaluate the influence of body size, activity patterns, socioeconomic status, nutrition, and health on skeletal aging and how it differs between Thai and geographically distant populations.