Differences of mineral content and width of the radius and its relevance for determining dexterity on skeletal material

Comparison of bone density on the dominant and nondominant sides between healthy elderly individuals and stroke patients

[Purpose] This study evaluated differences between healthy elderly individuals and stroke patients by comparing their dominant and nondominant sides. [Subjects and Methods] Thirty-five elderly individuals participated in this study and divided into a stroke group and a control group. The outcome measures were general characteristics and bone mineral density. Bone mineral density was evaluated by using the osteoporosis index. OsteoPro, T score, and Z score were used for the calcaneus region of the dominant side, and OsteoPro was used for that of the nondominant side. Data were analyzed by using the SPSS 12.0 software, paired-samples t-test, and independent-samples t-test. [Results] The T and Z scores showed no significant differences between the dominant and recessive sides in the control group. However, the stroke group showed significant differences in osteoporosis index, T score, and Z score between the paretic and nonparetic sides. Changes in the scores between the recessive and dominant sides showed significant differences between the two groups. [Conclusion] A positive relationship was found between physical activity and bone mineral density in the stroke patients. Therefore, improved physical activity can be beneficial by reducing osteoporosis in stroke patients.

Enthesis bilateral asymmetry in humans and African apes

Entheses (skeletal muscle and tendon attachment sites) have often been used to infer handedness and activity variability among human populations. However, the specific roles that intensity vs. frequency of muscle contractions play in modifying entheses are not well understood and the assumption that entheses reflect muscle activity levels has been challenged. This study explores the effect of habitual muscular activity on enthesis morphology in humans and African apes by investigating bilateral asymmetry in the forelimbs and hindlimbs of these taxa. Humans have generally more developed entheses in the lower limb while African apes have generally more developed entheses in the forelimbs. All species studied have more asymmetric forelimbs than hindlimbs except humans that show more asymmetrical expression of bony spurs in the lower limbs than in the upper limbs. When comparing species, humans are always more asymmetric in ethesis development than apes for both the forelimbs and hindlimbs, which reflects the relatively greater asymmetry in limb use in humans and the more symmetric use in apes. Enthesis development may reflect cross-symmetry patterns in humans and, more subtly, a moderate handedness in apes during manipulative activities. This study suggests that enthesis morphology provides information on muscle activity levels, with greater development of entheses associated with more habitual or powerful muscle use. The general similarity of ape and human responses to muscle activity suggests that muscle activity influenced enthesis development in Plio-Pleistocene hominins and that interpretation of muscle markings in these fossils can provide data for functional inferences in these extinct species.

Handedness in past human populations: Skeletal markers

Although it is generally believed that right-handedness has predominated in all human populations since at least the appearance of Homo sapiens sapiens, the evidence has rarely been studied in its entirety. This paper contains a review of the principal skeletal indicators of handedness (cranial and post-cranial), and an introduction to their use to estimate the prevalence of left and right handedness in the past. The role of such reviews is to enable us to assess the testability of genetic models of human handedness and of its evolution, using anthropological and archaeological data.