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Class Notes: Human Osteology

Wednesday: November 2, 2011

Week 9: Age, Ancestry & Sex

Tuesday:

For class purposes, we have defined Young Adult to be 18-35, Middle Adult to be 35-50, and Old Adult to be over 50. For sub-adults, dental formation is key to aging, but for adults all teeth have been erupted so other methods are needed. Aging adults in bioarchaeology is really more about serial relationships among the population than true chronological age of individuals. One of the ways a skeleton can be aged at time of death is by examining the pubic symphysis. As mentioned in an earlier post, this area will experience a break down over time. The 1920’s model by Todd was the first, with 10 stages denoted by qualitative descriptions. In 1990, Suchey and Brooks developed another method similar to Todd’s but with only 6 stages and that also divides between males and females.

A second method of scoring skeletal age at death is through Lovejoy’s examination of the auricular surface. This is the ear-shaped surface created by the joint between the sacrum and the ilium.

A third method is identifying suture closure status of the cranium. Looking at standard points along the suture lines and scoring between open through obliterated can help identify age.

Thursday:

We used the above methods for our skeletal projects. Then we discussed how to sex a skeleton. Obviously without the fleshy bits, this is easier said than done. However, our species like most does incorporate a certain amount of sexual dimorphism in general. Not always true, men tend to be about 5-10% larger than females in both length and robusticity. This includes metric and non-metric traits alike. The best place to find sex indicators is the pelvis, although the skull can also have good evidence.

Friday:

We went into further detail over sexing a skeleton. Males tend to have a larger malar region and larger canines. Their jaws tend to be more vertical and have a wider ramus, while also showing a wider and larger chin. Females tend to have a gonial inversion of their mandibles. In the pelvic area, several indicators are present. These include the symphysis shape, pubic length, shape of obturator, ventral arc, medial aspect ridge, subpubic angle, greater sciatic notch, preauricular sulcus, elevated auricular surface, ischial tuberosity, shape of auricular surface, subpubic concavity, sacrum curl, and size of alae.

It is important to note that these features are not accurate 100% of the time. The dichotomy of sex must be understood as two bell curves with an overlap between them. Indeed, there are effeminate men and masculine women in all cultures and through all time. Young men also will have more slender characteristics than their older counterparts. Older women, after menopause, will start to show masculine traits of their skeleton. Therefore, many different variables need to be scored together to identify sex, and this is often why sometimes you will see “indeterminate sex” because it is a toss up between male and female indicators or not enough indicators were preserved for a confident classification.

 

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2 remarks!

  1. Good luck in finding out the sex of the bones. I have a hard time figuring out if it is man or woman here when they are fully clothed – Keep up the good work. Enjoy yourself. Ruth

  2. My how times change, eh? :)

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