Forearm pronation efficiency in A.L. 288-1 (Australopithecus afarensis) and MH2 (Australopithecus sediba): Insights into their locomotor and manipulative habits.

Objectives: The locomotor and manipulative abilities of australopithecines are highly debated in the paleoanthropological context. Australopithecus afarensis and Australopithecus sediba likely engaged in arboreal locomotion and, especially the latter, in certain activities implying manipulation. Nevertheless, their degree of arboreality and the relevance of their manipulative skills remain unclear.

Activity-related sexual dimorphism in Alaskan foragers from Point Hope: Evidences from the upper limb.

Ipiutak (100BCE-500CE) and Tigara (1200 - 1700CE) are two populations from Point Hope, Alaska. As commonly observed in forager communities, it may be expected males and females to have been involved in markedly different daily activities. Nevertheless, activity-related sexual dimorphism in these populations has been scarcely studied.

Analysis of the forearm rotational efficiency in extant hominoids: new insights into the functional implications of upper limb skeletal structure.

The greatly diversified locomotor behaviors in the Hominoidea impose different mechanical requirements in the upper limb of each species. As forearm rotation has a major role in locomotion, the skeletal structures involved in this movement may display differences among taxa that reflect functional adaptations. To test this, we use a biomechanical model that quantifies the rotatory capacity of pronator teres (rotational efficiency) from skeletal measurements.

Biomechanics of forearm rotation: force and efficiency of pronator teres.

Biomechanical models are useful to assess the effect of muscular forces on bone structure. Using skeletal remains, we analyze pronator teres rotational efficiency and its force components throughout the entire flexion-extension and pronation-supination ranges by means of a new biomechanical model and 3D imaging techniques, and we explore the relationship between these parameters and skeletal structure. The results show that maximal efficiency is the highest in full elbow flexion and is close to forearm neutral position for each elbow angle.

Functional plasticity of the human humerus: shape, rigidity, and muscular entheses.

The relationship between the mechanical loading undergone by a bone and its form has been widely assumed as a premise in studies aiming to reconstruct behavioral patterns from skeletal remains. Nevertheless, this relationship is complex due to the existence of many factors affecting bone structure and form, and further research combining structural and shape characteristics is needed. Using two-block PLS, which is a test to analyze the covariance between two sets of variables, we aim to investigate the relationship between upper-limb entheseal changes, cross-sectional properties, and contour shape of the humeral diaphysis.

3D analysis of the forearm rotational efficiency variation in humans.

Pronosupination is a component of the hominoid orthograde corporal plane that enables primates to execute efficient and sure locomotion in their habitat and is an essential movement for the development of manipulative capacities. We analyze human variability in the rotational efficiency of the pronator teres muscle by applying the biomechanical model created by Galtés et al. (Am J Phys Anthropol 2008; 135:293-300; Am J Phys Anthropol 2009a; 140:589-594) to skeletal remains of a human sample (N = 29) and three nonhuman hominoid specimens (chimpanzee, gorilla, and orangutan) by means of 3D technology.