When developing a biological profile of unidentified human remains, forensic anthropologists routinely estimate sex, age, ancestry and stature. Body mass, on the other hand, is generally not included. But, research has shown body mass can affect certain biological characteristics, including age—meaning estimates for individuals outside “normal” BMI may be incorrect.
“As a forensic anthropologist, if I knew the individual was obese, I would give a much broader age range in my report. It probably is as good or better than stature,” Danny Wescott, director of the Forensic Anthropology Center at Texas State University (FACTS), explained to Forensic.
Wescott, his anthropology colleague Deborah Cunningham and researchers at Johns Hopkins University just received a two-year, $680,000 grant from the National Institute of Justice to support their research into and development of a novel method for the accurate estimation of body mass category of skeletal remains.
Wescott and Cunningham will use high-resolution computed tomography (CT) scanning to examine joint size, trabecular bone structure, bone shaft cross-sectional properties and whole bone shape to see if there are any visible differences that can be attributed to obesity and its effect on weight-bearing bones of the skeleton.
“If you are heavier, you are putting more ground reaction force on your bone, therefore your bones react to that,” Cunningham told Forensic. “There should be certain characteristics you have that we can predict that would be associated with that. So, can we utilize this information to predict an individual’s body mass category?”
To make it simple, the researchers are using the same BMI scale the World Health Organization does: very severely underweight, severely underweight, underweight, normal (healthy weight), overweight, obese class I (moderately obese), obese class II (severely obese), and obese class III (very severely obese).
With high-res CT scanning, the anthropologists can achieve resolution down to 15 microns. However, a lot of researchers do not have access to this type of advanced technology. Thus, the research team also plans to use medical CT scanners to see if they can provide the same level of bone-wear information they expect from the high-res CT images.
“We want this method to be applicable to law enforcement and forensic anthropologists across the country and across the world. There is always a hospital in the area with a medical CT scanner,” Cunningham said.
This is where the research team at Johns Hopkins will step in. While FACTS will scan and reconstruct the skeletal remains, scientists at the Massachusetts university will use their image processing and trabecular bone analysis software to carry out analysis of the data generated by Texas State.
“At the end of the two years, what we would like is to have a web-based model that people can put their images into and the algorithm would give them a prediction of BMI category with the associated confidence intervals,” Wescott said.
In addition to correcting age estimation associated with underweight or obese individuals, the new method can also make a difference in the accuracy of facial reconstructions. A forensic artist may draw a face much differently given a high level of confidence in BMI category.
“Based on the fact that 40% of Americans are obese, that means a very large percentage of people that wind up as forensic cases are going to be obese, and right now, we really have no way of knowing how that affects everything else we do,” said Wescott.
Photo credit: FACTS