Meaning of biodistance statistics: A test case using adult monozygotic twins

Abstract

Anthropometry, historically one of the primary research techniques in physical anthropology, has been widely utilized in biodistance studies. The complex genetic and environmental interaction that governs the expression of anthropometric dimensions, together with concerns over measurement error, have sometimes clouded the interpretation of biodistances based upon anthropometry. In this study, 51 pairs of adult monozygotic twins were analysed using discriminant analysis and Mahalanobis' generalized distance. Both male and female twins, grouped by first- versus second-born, displayed very small, statistically insignificant distances between groups. When literature estimates of intra-observer measurement errors were used as a frame of reference, the average absolute differences between the twin pairs were approximately twice the size of the measurement error estimates. The results of this study suggest that, first, the environmental effect upon the genetically influenced traits measured by anthropometry is not large enough to bring about significant multivariate differences between identical twin pairs; and, second, biodistance studies based upon anthropometry can be reliable so long as measurement error is minimized.

Interobserver error in scoring nonmetric cranial traits.

“…When someone's anthropological data are compared with the data of other researchers, the inconsistency of measurements or trait scorings becomes a serious problem for making comparisons. Many anthropologists have examined intra-and interobserver errors in craniometry (PAGE, 1976;UTERMOHLE and ZEGURA, 1982;SAKURA and MIZOGUCHI, 1983;KOUCHI and KOIZUMI, 1985), anthropometry (JAMISON and ZEGURA, 1974;KOUCHI and HANIHARA, 1981;JOHNSTONE and MACK, 1985;SHIOZAWA, 1985;BENNETT and OSBORNE, 1986;JAMISON et al, 1989) and dental morphology (MIZOGUCHI, 1977(MIZOGUCHI, , 1978NICHOL and TURNER, 1986). Although it is commonly believed that nonmetric traits are subject to greater intra-and interobserver error than metric traits, only a few analyses on observer error have been made for nonmetric cranial traits.…”

Integrating genealogy and dental variation: contributions to biological anthropology

“…Further, while this type of study is useful, it misses the mark in that the relationships being reconstructed among archaeological samples are technically unknown . We might, instead, begin by conducting this type of work within the genealogical samples from which quantitative genetic parameter estimates were initially generated with the aim of refining analytical methods (see Jamison et al, 1989; Paul & Stojanowski, 2017). Another option is utilizing simulated datasets that reflect expectations driven by population genetic theory (see Nikita, 2015; Nikita & Nikitas, 2021).…”