Sex Flashcards
Methods for sexing juveniles
- Ilium: GSN - position and shape said to differ; not found to be discriminatory.
Auricular surface - said to be elevated in females; not discriminatory
Composite arch - male = single, female = composite; observer issues indicate unreliability in the method - Long bones, skull, teeth, mandible (metric and non-metric)
> Ultimately, shouldn’t sex remains until puberty has occurred; determine age first.
Benefits of morphological sex estimation
> Can allow for a rapid initial assessment of sex.
Can capture the presence of subtle qualitative differences not covered in metric.
preferred by many, said to be more accurate than metric.
Limitations of morphological sex estimation
> Subjective = dependent on observer experience and interpretation.
Morphological characteristics have been shown to differ between populations.
lack of standardization; reduced replicability.
Benefits of metric sex estimation
> objective/standardized/repeatable
Able to be tested statistically; reliability of estimate.
avoids observational bias
Limitations of metric sex estimation
> Introduces measurement error
a single measurement fails to encompass the variation in sexual dimorphism.
population and period specificity.
Washburn; sex differences in pubic bone
> Took maximum lengths of the ischium and pubis = ischium-pubis index
cutting point of 90 males = less, females = more.
updated to be males = less than 91, females = greater than 94.
sexes over 90% of skeletons provided they belong to one major ancestral group.
acetabular point of measurement is ill-defined and inconsistent.
Thieme and Schull modified the index which resulted in an improved accuracy of 95%.
Acetabulo-pubic index methods
> Nagesh et al + Schulter-Ellis
Indices that take advantage of the greater proportion of the pubis in females are more accurate than those based on GSN.
Sciatic notch/acetabular index
> Kelly; GSN width/vertical diameter of acetabulum x 100, >88 = female, <86 male, 90% accuracy.
Said to use robust areas of pelvis which are more likely to remain intact.
Maclaughlin and Bruce; tested index on European remains = poor consistency; sex bias; morphology proved more accurate; GSN especially shown to be poor discriminator; points of measurement are ill-defined and sometimes absent.
DFA pelvis sex estimation
- > Steyn and Iscan: modern Greek sample, 17 measurements from pelvis and sacrum, average accuracy 60-95%.
- > Patriquin, Steyn, Iscan: South African black and white
- 9 measurements; new measurements = pubic length, pubic width, ischial length.
- Significant differences found for both races. Ischial length = whites (95%), acetabular diameter = blacks (94%)
- population specificity of sex differences.
Considerations when estimating sex
> temporal and spatial variation between populations; re-evaluated for modern remains.
The effects of age on methods must be reviewed.
sex bias; a 1:1 ratio is expected.
overlap between sexes must be considered.
DFA is population specific.
methods should have clear error rates, validation studies etc.
Rogers humerus sexing method
> Humerus is said to be sexually dimorphic due to the different carrying angle; however, subtle.
Roger’s method assessed 4 traits: shape of the olecranon fossa,
trochlear constriction, trochlear symmetry, angle of medial epicondyle.
Olecranon fossa (greatest weighted): female = deep oval, male = shallow triangle.
Trochlear constriction: male = less, female = more, spool shaped.
Trochlear symmetry: male = asymmetrical, female = symmetrical.
Angle of medial epicondyle: male = flat, female = raised.
20th century anatomical collection; sex bias = greater males; high inter-observer error.
Falys revision of Rogers humerus
> Tested on St Brides collection (1650-1700).
4 traits shown to have significant combined discriminatory capacity.
Olecranon fossa shape has highest alone; greater classification accuracy than 4 combined.
Employed a framework to capture the range of variations; classifications of probable/indeterminate.
need to be tested on a modern population due to secular change.
