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Assessing Mortality Bias from Skeletal Markers

Traits found in a skeletal sample are frequently used to infer qualities of the living population from which the skeletons were drawn. However, traits observed in a mortality sample may not accurately represent the same traits in same-aged living individuals, a phenomena referred to as biological mortality bias. This research attempts to assess biological mortality bias in deciduous tooth emergence, a trait that is used for estimating chronological age in both living and skeletal samples.

Data on tooth emergence came from longitudinal studies of Javanese, Guatemalan, and Bangladeshi children. Each sample was divided into a living sample for those who survived through the study and a mortality sample for those who died during the study. Parametric hazards analysis was used to test for differences in the timing of tooth emergence between the living and mortality samples.
There were no significant differences between the living and mortality samples for Bangladesh and Java, although there was a trend toward delayed emergence in the Bangladesh mortality sample. The Guatemalan mortality sample exhibited advanced emergence of the posterior dentition for the mortality sample. This unexpected finding may be an artifact of the nutritional supplementation given in the Guatemalan study. No evidence of biological mortality bias was found in pooled analyses of all three samples.

We found limited evidence that deciduous tooth emergence in a mortality sample (e.g. a skeletal series) differs from the timing of emergence in the living population from which the mortality sample was drawn.