Biology Reference
In-Depth Information
commencing in early adulthood, the surface of the bone begins to change in predictable
ways. It is unclear as to why the bone surface changes the way it does, but it has long
been regarded as the most reliable skeletal indicator of age in adults (
Krogman and I¸can,
1986
). Its utility has been demonstrated for both paleodemography and forensic anthro-
pology (
Meindl and Lovejoy, 1989
).
T. Wingate Todd first began studying and publishing on age changes in the pubic bones in
1920. He described ten morphological phases (categories) with associated age ranges. The
early phases have very small age ranges (i.e., 2 or 3 year intervals) that gradually increase
until phase X (10), which encompasses all individuals 50 years and older. Todd groups his
phases into three stages: phases I
e
III, the postadolescent stages; phases IV
e
VI, during which
the outline of the symphyseal surface is developed; and phases VII
e
X, during which there is
a gradual decrease in bony buildup and finally a breakdown of bone.
Many authors have revised Todd's method on other skeletal samples (e.g.,
McKern and
Stewart, 1957; Gilbert and McKern, 1973; Katz and Suchey, 1989
). Although all of these gener-
ally agree with Todd's assessment of the age progression of the pubic symphysis, there is
disagreement about how to quantify these changes and how this information should be
transferred into an actual age estimate.
Rather than score the symphyseal surface as a whole,
McKern and Stewart (1957)
used
a sample from the Korean War dead (i.e., many young men) to develop six stages (0
e
5)
for each of three components: the dorsal demiface, the ventral demiface, and the whole
surface of the pubic symphysis. In this way, there are no distinct phases with associated
age ranges; rather, one can score all three components separately, sum the scores, and find
the associated age range in a provided table. Their component method was designed to trans-
late a large amount of morphological variation into a chronological age.
Gilbert and McKern (1973)
later reworked this method for females based on observed
differences between the sexes. They chose three components: the dorsal demiface, the ventral
rampart, and the symphyseal rim. For each of these components there are five developmental
phases that are scored; additionally a phase of “0” to denote absence is included.
Gilbert and McKern's (1973)
analysis also includes a description of developmental differ-
ences between males and females. The dorsal demiface was found to be the first site of age-
related changes, but the changes were accelerated in females. They also noted that the male
symphyseal rim encloses the dorsal and ventral demifaces, but in females it separates the two
because of the ventral rampart.
Todd (1921)
concluded that males and females differed by
2
e
3 years but Gilbert and McKern rather found a difference of 7
e
10 years in morphological
age between the sexes. The authors also studied the effect of parity (birthing) on aging the
female pubis. They could not articulate any concrete pattern, only cautioning that parity
can cause the symphyseal face to look older than it actually is.
Meindl et al. (1985)
were the first to statistically test the effect of ancestry and sex on pubic
symphyseal aging. The results of the analysis of variance (ANOVA) were not significant for
ancestry, sex, or any interactions between the three, but, not surprisingly, “age decade” was
significant (F
3.86, p
0.01), indicating that age significantly affects the expression of pubic
¼
<
symphysis morphology.
Although the Todd method considers the entire surface of the pubic symphysis and
therefore may fail to account sufficiently for the entire range of human variation,
Meindl
et al. (1985)
believe that it better represents the chronological changes of the pubic symphysis.
