Morphometric analyses of hominoid crania, probabilities of conspecificity and an approximation of a biological species constant

Publication date: Available online 18 September 2015 Source:HOMO - Journal of Comparative Human Biology Author(s): J.F. Thackeray, S. Dykes Thackeray has previously explored the possibility of using a morphometric approach to quantify the “amount” of variation within species and to assess probabilities of conspecificity when two fossil specimens are compared, instead of “pigeon-holing” them into discrete species. In an attempt to obtain a statistical (probabilistic) definition of a species, Thackeray has recognized an approximation of a biological species constant (T= -1.61) based on the log-transformed standard error of the coefficient m (log sem) in regression analysis of cranial and other data from pairs of specimens of conspecific extant species, associated with regression equations of the form y = mx+c where m is the slope and c is the intercept, using measurements of any specimen A (x axis), and any specimen B of the same species (y axis). The log-transformed standard error of the co-efficient m (log sem) is a measure of the degree of similarity between pairs of specimens, and in this study shows central tendency around a mean value of -1.61 and standard deviation 0.10 for modern conspecific specimens. In this paper we focus attention on the need to take into account the range of difference in log sem values (Δ log sem or “delta log sem”) obtained from comparisons when specimen A (x axis) is compared to B (y axis), and secondly when specimen A (y ...

Source: HOMO Journal of Comparative Human Biology - September 20, 2015 Category: Biology Source Type: research