Biology Reference
In-Depth Information
existing early dimorphism by improving measurement accuracy are the goal for sexing infant
and fetal remains.
Looking ahead to adolescent sex estimation, the pelvis of the male retains the more adoles-
cent shape, whereas the female pelvis adapts for childbirth starting at puberty as previously
stated. As explained above, this can give confidence to an assessment of sex in an early
adolescent if there are female characteristics present (
Buikstra and Ubelaker, 1994
). If there
are no female characteristics, this does not mean that it is the pelvis of a male; it could
also be a female who has not begun to develop these secondary characteristics.
The vertebrae show some of the best opportunity for subadult sex estimation during
the more problematic childhood to preadolescent phases (approximately 2
12 years). As
mentioned previously,
Gilsanz et al. (1997)
found sexual dimorphism in children younger
than 12 years in the lumbar vertebrae, most notably in the first lumbar vertebra (L1). In
this study, the size of L1 was more highly correlated with sex than with body weight, the
L1 being more than 11% smaller in girls. The authors concluded that sexual dimorphism
in preadolescence might be due to a spike in testosterone levels of infant males during the
first year of life (
Gilsanz et al., 1997
). Saunders explains that fetal testosterone from the testes
present from the tenth week to the fifteenth week in utero is responsible for the major sex
differentiation in infants (
Saunders, 2000
). After that time, the endocrine system contributes
to sexual dimorphism, including size and weight dimorphism (
Saunders, 2000
). After this
hormone peak in utero, hormone levels decrease and do not reach these peak levels again
until puberty. This may explain why, for example, the fetal sciatic notch shows sexual dimor-
phism, but there is little dimorphism present during the rest of childhood in the shape of the
sciatic notch.
Theoretically, dentition size should work for sexing subadults, as adult teeth begin devel-
opment and eruption during childhood. As with measuring the fetal bones, however, the
magnitude of this dimorphism may be too small to be significant (
Saunders, 2000
). Despite
this,
DeVito and Saunders (1990)
employed a multivariate approach with deciduous tooth
dimensions and achieved impressive sex estimation accuracy rates (75
e
90%), but there
was considerable population variation.
Hassett (2011)
measured the buccolingual and mesio-
distal diameters of the permanent canine teeth in adults and subadults and achieved 94%
accuracy. This author suggested the measurements be taken at the tooth cervix to avoid prob-
lems with tooth wear. The sample size in this study was small and this method could be
highly population specific, but this approach may provide a possible direction for future
research. Molleson and colleagues (1998) were able to combine multiple features in juveniles
from a Romano-British cemetery: the eye orbit, mandibular canine size, and the pelvic inlet.
This method reached only 78% accuracy, but has good potential for sex discrimination
considering the difficulty of sex estimation in subadults (
Buikstra and Ubelaker, 1994
).
Despite all the disparaging comments about the potential to accurately estimate sex in
subadults, there are at least some encouraging results published in this area.
e
DNA Analysis
One area that offers great potential for sex estimation in both subadults and fragmentary
adults is DNA analysis. Molecular methods are one area in which the term sex determination
could potentially be applied, due to alleles that only show up on the sex chromosomes. Some
