In one of my earlier Forensics 101 posts, I gave an overview of the different ways to determine the age of a skeletal victim. This process is much easier in children and teens as most of the major skeletal changes that occur during growth are ongoing until the early 20s. However, there are several ways to estimate age at death in an adult, and one of the most reliable is analysis of the pubic symphysis.
The pubic symphysis is the joint where the two halves of the pelvis meet at the centerline of the body, joined by a layer of fibrocartilage.
The bony symphyseal surface that faces the cartilage changes over time, starting at about age 20 and continuing past the age of 65.
The below sketch, based on the Suchey-Brooks method of identification, outlines the changes that take place over those 45 years. There are minor sex differences between males and females; the below sketch outlines the progression of an adult male over 5 – 10 year intervals and progressing through 6 phases:
Young bone is very robust, with a series of horizontal ridges and grooves. Over time, the bone changes from ridged and furrowed to flat and smooth with a fine grained texture. Margins build up at the edges to form a rim and a plateau develops in the center of the symphyseal surface at approximately age 35 (phase IV). After this, the surface erodes to become pitted and porous, and the shape becomes irregular. For the majority of the population, these changes occur at predictable age ranges, allowing an osteologist to estimate the age of an adult victim at the time of death.
The photo at the top of this post illustrates the extreme differences in the symphyseal surface over time. The bone on the left is from a young person of approximately 20 years of age. The bone on the right is from an older person of over 60 years of age.
After the recovery of skeletal or badly decomposed remains, basic markers such as age and sex are crucial to victim identification. Pubic symphysis analysis is simply one way a forensic anthropologist can determine victim age. If a full set of remains are recovered, it is preferable to analyze additional adult characteristics such as skull sutures and medial rib ends for a more accurate estimation.
Next week, I’ll be back with a new Forensic Case File– the story of a Union solider, quickly buried after the Battle of Antietam and lost to history for 146 years until his remains were uncovered by an overly ambitious groundhog. I hope to see you there…