Ecogeographic patterns in fetal limb proportions.

OBJECTIVES: Humans generally comply with the ecological rule of Allen (1877), with populations from tropical environments exhibiting body proportions in which limb segments are long relative to trunk height compared to temperate groups. This study tests whether ecogeographic differences in intralimb proportions are identifiable among two modern fetal samples of differing ancestry. MATERIALS AND METHODS: Data are derived from radiographic measurements of long bone diaphyseal length and crown-heel length (CHL) of contemporary, spontaneously aborted fetuses of African Americans ("black") of assumed African (tropical) ancestry and European Americans ("white") of assumed European (temperate) ancestry (n = 184). Population individual limb elements, brachial, and crural indices are compared via analyses of covariance (ANCOVA). Potential patterns of divergent allometric growth are quantified through principal components analysis (PCA). RESULTS: African ancestral distal limb elements were consistently, albeit slightly, longer than those of European ancestry, relative to CHL. None of the ANCOVA interactions with ancestry are statistically significant for limb indices. The radius was the only single element that displayed a statistically significant ancestry effect (p = 0.0435) equating to a 1 mm difference. PCA highlights that upper limbs demonstrate negative allometry and lower limbs demonstrate positive allometry with sample-specific multivariate growth patterns being nearly identical. Differences in growth allometry late in gestation make little contribution to observed differences in adult limb proportions. DISCUSSION: No statistically significant ecogeographic patterns were appreciated among intralimb proportions between these groups during the fetal period. This study contributes to a greater appreciation of phenotypic plasticity, ecogeographic variation in ontogeny, and the evolution of modern human diversity.

Possible Achondroplastic Dwarf Skull from Montevideo, Uruguay.

Achondroplasia (chondrodystrophia) is an autosomal dominant inherited disorder affecting approximately 1 in 26,000 live births and is the most common cause of dwarfism in humans. Disproportionate short stature and a suite of craniofacial characteristics typify achondroplasia. The literature available for differential diagnosis of the disorder relies primarily on the postcranial skeleton. In this paper, a possible case of achondroplasia is presented. The cranium presents a unique suite of cranial and craniofacial dysmorphologies. The lack of postcranial remains does not permit their use in the analysis. To make a differential diagnosis and to quantify the observed craniofacial dysmorphologies, craniometric data are compared to modern clinical literature and to craniometric data from known achondroplastic dwarfs. Thin-plate spline analysis is integrated to quantify the differences in degree and magnitude of shape change. This manuscript demonstrates an appropriate methodology for identifying achondroplasia from the cranial skeleton alone.

Structural analysis of human rib fracture and implications for forensic interpretation.

Patterns of rib fractures are of significant clinical and forensic interest. Linking patterns of rib fracture with specific physical events provides a foundation for understanding the nature of traumatic events that are associated with rib fracture in forensic contexts. In this study, isolated human ribs (n = 8) were end-loaded to failure to investigate: (i) local deformations (bone strain) prior to and during structural failure, (ii) location of ultimate failure, and (iii) fracture mode. Structural properties of ribs were used to calculate theoretical stresses to determine whether such calculations could be used to predict site of fracture. Ribs fractured on the sternal side of midshaft in all experiments, but mode of failure varied with transverse, buckle, spiral, and "butterfly" fractures observed. Comparison of calculated stress with observed strain values suggest that experimental, rather than theoretical, approaches will be most productive in furthering understanding rib fracture in forensic contexts.

Post-cremation taphonomy and artifact preservation.

Contemporary commercial cremation is a reductive taphonomic process that represents one of the most extreme examples of postmortem human alteration of bone. The thorough reduction and fragmentation of cremated human remains often leaves little biological evidence of diagnostic value. Instead, non-osseous artifacts often provide the best evidence of the origin of the cremated remains, the identity of the decedent, and commingling of the remains of more than one individual. Once human remains have been cremated they are most commonly placed into a processor and reduced into small fragments and fine ash suitable for inurnment or scattering. The type of processor determines the size and utility of the particulates and artifacts available for analysis. The newest type of processors have changed the manner and degree of postmortem bone modification and altered the preservation of diagnostic bone fragments and cremation artifacts. This paper addresses the impact of the newest cremation procedures on forensic analysis of cremated remains.