Biological mortality bias in diaphyseal growth of contemporary children: Implications for paleoauxology

Abstract

Objectives: Biological mortality bias is the idea that individuals who comprise skeletal samples (non-survivors) are a specific subset of the overall population, who may have been exposed to greater stress during life. Because of this, it is possible that studying growth in a skeletal population misrepresents the growth and health of survivors in that population. Using a modern sample, this study investigates whether biological mortality bias in growth may be present in archaeological skeletal samples.Materials and methods: Postmortem computed tomography scans of 206 children aged under 13 years were collected from two institutions in the United States and Australia. The sample was separated into children who died from natural causes as proxies for non-survivors and from accidental causes as proxies for survivors. Differences in long bone length for age were assessed through analysis of covariance (ANCOVA) and z-score analysis, and these results were compared with studies linking anthropometrics and mortality risk in nonindustrialized societies.Results: Differences in growth favoring survivors were greater for girls than for boys and seemed to increase over age. The effect in nonindustrialized societies was 1.5 to 5 times the magnitude of that in our contemporary sample.Conclusions: A greater growth delay in girls than in boys has been documented in historical identified collections, and skeletal samples consistently become more stunted relative to modern standards over the course of growth. Our findings on biological mortality bias could explain part of these growth delays and impact interpretations of past ontogenetic environments.bioarchaeology, growth and development, long bone, osteological paradox, skeletal growth profiles | INTRODUCTIONIn The Osteological Paradox, Wood et al. (1992) outline a series of scenarios in which bioarchaeological conclusions drawn from skeletal samples might not reflect the health of the surviving segment of the population. Shortly after, Saunders and Hoppa (1993, p. 129) coined the term biological mortality bias, referring to the "physiological and morphological difference between those who die and those who survive." Biological mortality bias is a problem for all bioarchaeological analysis, but it is especially problematic for paleoauxology, or the study of growth in the past (Tillier, 1995), because growth is known to be environmentally sensitive (Bogin, 1999). This property has made

Growing taller unequally? Adult height and socioeconomic status in Spain (Cohorts 1940–1994)

“…Height differentials by SES (regardless of the approximation used) among men are larger and they vary more over time with respect to women. These differences between the sexes could be related to both a higher eco-sensitivity (i.e., susceptibility to environmental conditions and changes in them over time) among men ( Cámara et al, 2021 , Zimina et al, 2019 ; Thurstans, 2020b , Thurstans, 2020a ; Spake et al, 2022 ) and to the fact that access to higher education for older female cohorts was very limited in Spain ( Ballarín Domingo, 2001 ; Heath & Jayachandran, 2016 ; Plötz, 2017 ). We are inclined to believe that the role of eco-sensitivity is more influential in this regard, given that the results of the analysis based on the educational attainment of the household head (mostly men) paint the same picture.…”

New More Generic and Inclusive Regression Formulae for the Estimation of Stature from Long Bone Lengths in Children

“…See Table 1 for details about the range and distribution of the ages in the model and test samples. All four datasets (HTHOC, NMDID, LC, and VIFM) include children of documented sex, age-at-death, date of birth and death, and cadaver length, and also include other biographic data, such as cause of death and assigned "race" [1,23,[26][27][28]. Decimal ages were calculated from birth and death dates for all individuals in the NMDID, LC, and VIFM datasets.…”

“…The collection includes the skeletons of individuals who have been identified as "Black", "Negro", "Colored", "African", or "White" Americans of low socioeconomic status who died mostly in the Cleveland area [23]. In the NMDID dataset, dates of death range from 2011 to 2017 and include a variety of socioeconomic status children, mostly underprivileged, who died in the state of New Mexico, USA, and whose death was subjected to medico-legal death investigation [27,28]. In the NMDID dataset, individuals were originally assigned to "White", "Black", or "Native American" "race" groupings, with an additional field for "Hispanic" ethnicity as coded by the medicolegal institution.…”

“…The LC dataset includes the remains of low to middle-socioeconomic children who were autopsied and whose remains were exhumed from local cemeteries in the city of Lisbon, Portugal, having died between 1957 and 1972 [1]. Children in the VIFM dataset is comprised of children who died in the state of Victoria, Australia, and whose deaths were also subjected to medico-legal death investigations between 2011 and 2017 [27,28]. Table 1 displays the sample size breakdown by dataset, age, and sex.…”

“…Both the HTHOC and LC are historic datasets considered to include children who lived under adverse living conditions and who are moderately to severely stunted [23] and thus are significantly shorter for age compared to a modern reference standard. In comparison, the NMDID and VIFM datasets can be said to include "normal" modern children who lived under more favorable conditions to HTHOC and LC and do not show significant height-for-age deficits relative to a modern standard [27,28]. Thus, by pooling the HTHOC and NMDID samples, we created a model sample that incorporated a greater range of biological variation than would be present in either of those groups alone and reflected a range of social experiences of growth.…”