Biology Reference
In-Depth Information
FIGURE 11.12
Plot of
250 simulated ages against
femoral lengths. The solid
lines show the 95% confi-
dence intervals for age esti-
mates, which contain 230 of
250 cases (92% of the data).
10
20
30
40
Femur Length (cm)
limits, plotted in
Figure 11.13
as a step function. Based on the comparison of stated and actual
coverage, the wobble in the calculated 95% confidence intervals is negligible.
WHAT SEX RATIOS AND AGE-AT-DEATH STRUCTURES CAN TELL
US ABOUT PAST POPULATIONS
This chapter provides tools for estimating the sex ratio and age-at-death distribution for
a skeletal sample using reference information and demographic models prior to estimating
individual sex or age-at-death. Conducting the analyses in this order allows you to generate
probabilities and reliability estimates for the skeletal data relative to what is known or
expected for the relationship between osteological indicators and sex and/or age. The exam-
ples amply demonstrate that relying on individual sex estimates and “age indicators” from
the skeletal sample to initially generate the demographic parameters (treating skeletal “sex
estimates” or “age indicators” as known) will produce incorrect results. Following the course
prescribed above also gives you the analytical basis on which to make a broad range of bio-
logically and culturally based demographic comparisons as we outline below.
Skeletal biology has long contained elements of both a descriptive and an analytical
science, although much of earlier skeletal biology was relegated to simple osteological
descriptions in the appendices to various reports, as
Buikstra (1991)
notes. Current skeletal
