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ASM 275 / ASM275
Estimating Age - Adults (Lab 10)
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Exported for Carolyn Ginger on Wed, 07 Nov 2018 06:50:47 GMT
Pubic symphysis with residual billowing on the face. [1]
By the end of this lab, the student will be able to:
Describe the biological basis for adult age estimation using skeletal indicators. Describe the biological and anatomical basis for the changes in the pubic symphysis.
Evaluate cranial suture closure as an indicator of age and apply a standard approach for scoring cranial suture closure and generating an age estimate. Apply charts of epiphyseal union timing to estimate age at death.
Age Estimation from Skeletal Traits
Joint Deterioration
During the process of aging, joint surfaces (where two bones meet or articulate) change in their morphology. Through joint deterioration, the surfaces change from being smooth and organized in appearance to more disorganized in appearance, porous and with bone growth (called osteophytes) around the edges of the joints.
Several joints in the skeleton provide better estimators of age because their breakdown follows established processes. These include the pubic symphysis, the auricular surface, and the sternal ends of the ribs (the 4th rib in particular). Here we will focus on the pubic symphysis because it is a classic method and the easiest to understand and apply.
Because developmental traits, like the ones used to age subadults, proceed more regularly and consistently than degenerative traits, age estimates for subadults tend to be more accurate and within a smaller range of error than age estimates for adults and the elderly. That is, whereas subadult age estimates may be +/- months, adult age estimates will be +/- years, and in many cases the age range can be larger than a decade.
Pubic Symphysis Aging
The pubic symphysis is the joint that connects the os coxae on the anterior portion of the pelvic girdle. Although mostly immobile, the joint does experience some movement, which results in cumulative changes in the joint surface as you age. The details of this process are slightly beyond this level of course, but some broad strokes are possible. Imagine separating the pelvis at the pubic symphysis as shown below. All subsequent images are as if you were looking straight at the face of the pubic symphysis.
Pelvic girdle showing the location of the pubic symphysis. [2]
The pubic symphysis is actually one of the easier aging systems for students to understand, but it is still somewhat difficult to wrap one's head around the anatomy. The image below is of a real pubic symphysis. Imagine separating the model above at the blue line and looking straight at the pubic face. This is what you would see. The joint surface itself is roughly oval in appearance. There is an upper and lower end (extremity) and the face is divided into a dorsal and ventral rim/margin. Can you tell how old this person was when he/she died? By the end of this lab you should be able to.
Left pubic symphysis. [3]
For the rest of this lab I only show you pubic symphyses from the LEFT side. This makes things easier; dorsal (posterior, back) is always to the left, ventral (anterior, front) is always to the right. In addition, I use 3D scans of pubic symphyses rather than actual bone specimens because it is easier to show the changes that occur in this joint as one ages because the depth of the bone is easier to visualize. [Show Less]