This presentation highlights research that illustrates the impact of secular change and reference sample composition on the accuracy and precision of forensic skeletal age-at-death estimation.
Forensic anthropologists are often tasked with determining skeletal age-at-death to assist law enforcement in identifying skeletal remains. If the remains are skeletally mature, degenerative changes in articular surfaces are typically assessed to determine age. If the skeleton is immature tooth eruption, dental development, and/or epiphyseal union are used to estimate age. Forensic anthropologists derive an age-at-death estimate by comparing our assessment of skeletal age indicator(s) to standards derived from skeletal collections of known age-at-death. Prior to the establishment of modern skeletal collections such at the William M. Bass Donated Collection at the University of Tennessee, anthropologists developed age estimation techniques using late 19th and early 20th century anatomical collections (e.g. the Hamann-Todd Osteology Collection at the Cleveland Museum of Natural History and Terry Anatomical Collection at the Smithsonian Institution); however, research on Bass Collection skeletons has demonstrated remarkable changes in skeletal morphology in modern Americans compared to early 19th century birth cohorts, illustrating that standards derived from modern populations are imperative for forensic casework; anatomical collections and archaeological samples are not appropriate reference samples. Age estimation in forensic casework is further complicated by the age distribution of the forensic case population. Forensic cases often involve accidental deaths, homicides, and suicides of individuals from a younger age demographic than natural deaths which comprise many of the reference samples used to derive age estimates. This difference between the age distribution of the reference sample and that of the "target" population leads to 'age mimicry', whereby skeletal age-at-death may be under-estimated. The documentation of significant changes in skeletal morphology illustrates what evolutionary biologists already know, i.e., phenotype is dynamic, not static. These short-term evolutionary changes in skeletal form have implications for anatomical research beyond the hard tissues. (publisher abstract modified)