The complex array of carpals, metacarpals, and phalanges that form the hand skeleton holds significant information for forensic analysis. When larger, more commonly studied bones like the pelvis or femur are absent, fragmented, or damaged, hand bones become a valuable substitute for establishing a deceased individual’s biological profile and life history. The dense and numerous bones of the hand often survive deterioration and trauma better than other skeletal elements, allowing forensic anthropologists to piece together details about the person, their habits, and the circumstances of their death. Analysis of these bones provides a specific window into a person’s age, sex, activity, and medical history.
Estimating Age and Biological Sex
Hand bones are particularly informative for estimating the age of subadult remains due to the predictable sequence of epiphyseal fusion. Epiphyseal fusion describes the process where the growth plates, or epiphyses, at the ends of long bones unite with the main shaft, or diaphysis, marking the end of skeletal growth. This process provides a relatively narrow window of age estimation up until the late teens and early twenties.
The wrist and hand region is often utilized by observing the fusion of the distal radius and ulna. In females, complete fusion of the distal radius typically occurs between 17 and 18 years, while in males, it is often seen between 18 and 19 years. The precision of this method decreases significantly once an individual reaches full skeletal maturity, generally around 25 years, as the bones cease to change predictably.
Determining biological sex from hand bones is less reliable than using the pelvis or skull, but it remains a viable supporting technique when those elements are missing. Researchers employ metric analysis, measuring the length and width of the metacarpals and phalanges to identify patterns of sexual dimorphism. Males generally exhibit larger and more robust hand bones. Width measurements often show a greater degree of difference between the sexes than length measurements.
Studies using these measurements in specific populations have demonstrated classification accuracy rates ranging from 80% to over 90% in distinguishing between male and female remains. Because the degree of robusticity varies significantly across populations, the analysis must rely on population-specific standards for the most accurate results. This supporting evidence can be important for narrowing the pool of potential identities in a forensic investigation.
Indicators of Lifestyle and Chronic Use
The hand skeleton is a repository of long-term mechanical stress, reflecting a person’s habitual activities and occupation through subtle changes in bone morphology. Repeated, strenuous use of specific muscles results in the remodeling and strengthening of the areas where tendons and ligaments attach to the bone. These attachment sites, known as entheses, can become more rugged, enlarged, or pitted—a phenomenon called musculoskeletal stress markers (MSMs).
Handedness
Differences in robusticity between the dominant and non-dominant hand can provide clues about handedness, as the bone structure of the hand used for repetitive, powerful motions tends to be slightly denser. A person who engaged in heavy manual labor involving gripping or striking may exhibit more pronounced MSMs on the metacarpals and phalanges of their dominant hand. Individuals whose work involves fine motor skills might show different, more localized patterns of stress than those who performed heavy lifting.
Stature Estimation
Measurements of hand bones can also be used to estimate an individual’s living stature, particularly when complete long bones like the femur or tibia are unavailable. Regression formulas correlate the length of bones, such as the metacarpals, with overall height. The second through fifth metacarpals are generally preferred for this calculation. While not as accurate as using a complete long bone, the error in estimation is sometimes less than 3%.
Analysis of Trauma and Disease
The hand bones can offer physical evidence regarding the circumstances surrounding death and an individual’s medical history. Perimortem trauma, injuries sustained at or near the time of death, is frequently observed in the hands, often in patterns consistent with defensive actions. Fractures to the metacarpals, common with blunt force trauma, can result from striking an assailant or from passively raising the hands to shield the head or face. These “defensive injuries” are suggestive of homicide and indicate the victim was actively attempting to ward off an attack. Sharp force trauma, such as incised wounds from a knife, may also be visible on the hand bones. Analyzing the fracture patterns or cut marks helps determine the type of weapon and the force used.
The hand joints are also highly susceptible to the effects of systemic and degenerative diseases, leaving recognizable traces on the bone surface. Severe arthritis, for example, manifests as joint degeneration, bony spurs, and pitting in the carpal bones and the ends of the metacarpals and phalanges. Metabolic disorders like rickets or certain chronic infections can leave lesions or deformities on the hand bones, providing a window into the deceased’s long-term health.