[show abstract][hide abstract] ABSTRACT: In this paper we critique two recent studies that have been claimed to disprove the Out of Africa hypothesis for modern human origins (Hawks et al., 2000; Wolpoff et al., 2001). We show that the test prediction employed by Hawks et al. (2000) and Wolpff et al. (2001) is not relevant to many versions of the Out of Africa hypothesis, and that the key specimens they used are problematic in terms of morphological representativeness. We also show that there are significant problems with the character state datasets employed in the studies. Lastly, we highlight evidence that the main method used in the studies (pairwise difference analysis) is not reliable when applied to the type of data employed by Hawks et al. (2000) and Wolpoff et al. (2001). In view of the foregoing, we contend that Hawks et al.'s (2000) and Wolpoff et al.'s (2001) claim to have disproved the Out of Africa hypothesis cannot be sustained.
The Anatomical Record Part A Discoveries in Molecular Cellular and Evolutionary Biology 09/2004; 279(2):701-7.
[show abstract][hide abstract] ABSTRACT: In the present study the course of the squamotympanic fissure of the mandibular fossa is examined in several fossil hominid specimens. While previous work by several authors had found that the course of this fissure was potentially autapomorphic for the Ngandong and Sambungmacan fossil samples from Indonesia, a more recent study performed by Delson et al. (Anat Rec 2001; 262:380--397) reported that a number of other fossils, including OH 9, Sangiran 4 and 17, and KNM WT 15000 were similar to the Ngandong and Sambungmacan specimens in the expression of this feature. To test these findings, those specimens purported to share similarities with Ngandong and Sambungmacan were examined. The results of this study indicate clearly differing morphologies between the Ngandong and Sambungmacan fossils, on the one hand, and the four African and Indonesian fossils named by Delson et al. (2001). Hence, the course of the squamotympanic fissure remains a potentially autapomorphic feature separating the Ngandong and Sambungmacan samples from the remaining specimens allocated to Homo erectus.
The Anatomical Record 04/2002; 266(3):138-41; discussion 142-5.
[show abstract][hide abstract] ABSTRACT: Allometry is an important factor of morphological integration that contributes to the organization of the phenotype and its variation. Variation in the allometric shape of the mandible is particularly important in hominid evolution because the mandible carries important taxonomic traits. Some of these traits are known to covary with size, particularly the retromolar space, symphyseal curvature, and position of the mental foramen. The mandible is a well studied system in the context of the evolutionary development of complex morphological structures because it is composed of different developmental units that are integrated within a single bone. In the present study, we investigated the allometric variation of two important developmental units that are separated by the inferior nerve (a branch of CN V3). We tested the null hypothesis that there would be no difference in allometric variation between the two components. Procrustes-based geometric morphometrics of 20 two-dimensional (2D) landmarks were analyzed by multivariate regressions of shape on size in samples from 121 humans, 48 chimpanzees, and 50 gorillas (all recent specimens), eight fossil hominids from Atapuerca, Sima de los Huesos (AT-SH), and 17 Neandertals. The findings show that in all of the examined species, there was significantly greater allometric variation in the supra-nerve unit than in the infra-nerve unit. The formation of the retromolar space exhibited an allometric relationship with the supra-nerve unit in all of the species studied. The formation of the chin-like morphology is an "apodynamic" feature of the infra-nerve unit in the AT-SH hominids. The results of this study support the hypothesis that allometry contributes to the organization of variation in complex morphological structures.
The Anatomical Record Part A Discoveries in Molecular Cellular and Evolutionary Biology 07/2004; 278(2):551-60.
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