Forensic researchers from North Carolina State University have identified a more accurate way to assess an individual's age at death, based on the bone mineral density of the femur. The technique could be used to help identify human remains.

Current techniques for assessing an individual's age at death rely on reviewing the wear and tear on a skeleton's joint surfaces, said Ann Ross, a professor of biological sciences at NC State and corresponding author of a paper on the work.

However, there is a lot of variabilities there, based on an individual's lifestyle and how a forensic practitioner interprets those skeletal features. Depending on the method being used, current approaches could list a deceased individual in his or her 40s as being anywhere from 27 to 70 years old.

However, bone mineral content and density increase as we grow, then decline at a fairly steady rate once we reach adulthood – making it a potentially useful way of assessing age, Ross added.

While using bone mineral density to assess age is a concept that has been around for several years, the NC State team has found a way to fine-tune the practice. Specifically, the researchers found that assessing bone mineral density at the neck of the femur provided the best sampling data for determining age.

In a study assessing the remains of 33 men and eight women, the researchers found that bone mineral density could be used to determine age within a 13-year margin of error. This, in itself, is a step in the right direction, Ross said.

However, the research team think the method could be made even more accurate if they were able to significantly increase the sample size, including more women and more representatives from each age group.

The researchers found no significant difference between men and women based on the bone mineral density of the femur. However, they did find the difference between sexes in the density of the skull.

The researchers think the skull is better for assessing sex because it is not a load-bearing bone, meaning it is subject to fewer outside forces – allowing forensic practitioners to detect bone mineral density differences that result from an individual's biological sex.

Ross concluded that while promising, the team did not have a large enough sample size to draw firm conclusions about using bone mineral density to determine sex – that would require a larger study.