Biology Reference
In-Depth Information
Recently,
Ousley et al. (2010)
collected long bone length data on radiographs of known-age
subadults at medical examiner offices and other clinical settings around the United States.
This database (including formation and union of ossification centers, and long bone lengths)
will soon be available for use by forensic anthropologists and other researchers. In the presen-
tation, they cited the need for modern reference samples because modern North American
children grow faster than those born in the 1950s (measured by Maresh and others) (
Ousley
et al., 2010
). Most research points to a secular trend towards a faster and longer period of
growth inWestern populations, usually attributed to diet, because of either increased calories
and/or nutrition (
Danubio and Sanna, 2008
), or chemicals and hormones (i.e., bovine growth
hormone) used in Western livestock and agricultural practices (e.g., see
Golub et al., 2003
).
As mentioned earlier,
Schaefer et al. (2009)
have compiled the results of many studies on
the relationship of age-at-death to diaphyseal length of long bones. Again, the authors
provide information on the population used in each study, indicate number of males and
females used, and report whether the measurements were taken on wet (via radiograph)
or dry (forensic or archaeological) bones, as this could make a difference in the final calcula-
tion of size (
Hoffman, 1979
). For instruction on how to collect long bone measurements from
juvenile remains, consult Standards for Data Collection from Human Skeletal Remains (Buikstra
and Ubelaker, 1994), although
Schaefer et al. (2009)
should be consulted with regard to the
analysis/interpretation of these measurements.
Dental Development
Dental development is the most accurate means for estimating age-at-death in subadults,
probably because it is under fairly tight genetic regulation. Development of the dentition
involves the formation, calcification, and eruption of the crown, as well as root growth
and development. Refer to Hammerl (Chapter 10), this volume, for a review. Additionally,
Hillson (1996) is an authoritative source on tooth development.
Schour and Massler (1941)
and
Ubelaker (1989)
published charts illustrating 21 develop-
mental stages from about 5 months in utero to 35 years old. Neither chart is sex-specific
although many authors have noted sex differences (
Schour and Massler, 1941; Smith, 1991;
Smith, 2010
). Ubelaker's impetus was to create a chart to be used in bioarchaeological
contexts for prehistoric Native American remains, but the reproduction of his chart has
made it popular for anthropological application to both prehistoric and modern remains.
Smith (2010)
assessed both the
Schour and Massler (1941)
and
Ubelaker (1989)
charts on
a modern clinical sample of living subadults using panoramic radiographs from a dentist.
Her results show that each chart performs equally well, but that some of the stages, particu-
larly those around ages 7
e
9, are significantly different for males and females. She also found
that wider error intervals (age ranges) are needed for stages encompassing ages 6
e
14 years.
Again,
Schaefer et al. (2009)
have compiled the results of several dental analyses, including
Ubelaker (1989)
, in their manual. One must have experience with examination of skeletal and
dental remains to apply these charts in an age-at-death estimation. First, if the teeth were not
fully formed, an experienced anthropologist (or dentist) would have to identify the individual
teeth based on crown shape and development. Second, without knowledge of tooth formation
and eruption processes, one could easily misapply information from the charts and tables in
the analysis of subadult dental remains. Refer to Hammerl (Chapter 10), this volume, for more
information on dental development and age estimation from the teeth.
