Biology Reference
In-Depth Information
to this kind of analysis and it should be the future direction of research on morphological age-
related changes, as previously discussed.
Cranial Suture Closure
Todd and Lyon began their extensive study of endocranial (interior skull) suture
closure with European American males in 1924. They initiated this research because
“the whole question of the relation of suture union to age remains an intricate and
unsolved problem” (
Todd and Lyon, 1924
:329). Their study included over 300 crania of
known ages ranging from 18 to 84 years of age. While the authors had access to larger
numbers of crania, they eliminated individuals who did not have satisfactory documen-
tation of age-at-death and individuals for whom the postcranial skeleton was not avail-
able for comparison. During the course of their research they also removed several
crania that they deemed abnormal, thus critically reducing the amount of human varia-
tion in the sample.
The next year,
Todd and Lyon (1925a)
published their findings regarding ectocranial (exte-
rior skull) suture closure for the same collection of 307 European American males. In this
sample they found suture closure commences at the same time both endocranially and ectoc-
ranially. Once initiated, ectocranial fusion progresses more quickly and shows more indi-
vidual variation. For these reasons Todd and Lyon concluded that cranial suture closure is
not a very reliable aging indicator.
However, they also simultaneously published articles regarding both the endocranial and
ectocranial closure of sutures in African American males (
Todd and Lyon, 1925b,c
). Although
they only had 79 crania on which to base their conclusions, they believed that the establish-
ment of their first standard could serve as a basis for comparison and offset the need for
a larger sample. The results showed very little population difference in the closure of cranial
sutures.
Several decades later, in the 1970s, osteologists began reconsidering cranial suture closure
as a viable option for age determination (
Johnson, 1976; Perizonius, 1984; Meindl and Love-
joy, 1985; Mann et al., 1987, 1991; Masset, 1989; Galera et al., 1998
).
Meindl and Lovejoy (1985)
published a new method for age estimation from cranial suture closure. The authors claimed
that “no studies exist in which suture closure has actually been observed”(
Meindl and Love-
joy, 1985
:57, their emphasis), and posited that
Todd and Lyon's (1925a,b,c)
practice of elimi-
nating abnormal skulls from their studies is the reason for so much doubt as to the usefulness
of cranial suture closure.
Meindl and Lovejoy's (1985)
new method included observing one centimeter lengths of
specific anatomical locations on sutures (to aid with repeatability) and a four-point scoring
system: 0
¼
no observable closure, 1
¼
minimal closure (about 1
e
50%), 2
¼
significant closure
(about 50
e
99%), and 3
complete obliteration. Using the previous literature as a guide, the
authors narrowed down ten specific sites for observation and limited their study to ectocra-
nial sutures to increase the ease of use. These ten sites were divided into the “vault system”
and the “lateral
e
anterior system,” and modal patterns were investigated in each. The
lateral
e
anterior system was more regular. Similar to the pubic symphyseal aging techniques
of
McKern and Stewart (1957)
and
Gilbert and McKern (1973)
, the authors produced a table
of composite scores and a mean age and standard deviation for each score. However, as with
¼
