The upper limb skeleton and behavioral lateralization of modern humans from Zhaoguo Cave, southwestern China.

OBJECTIVES: Aims of the study are to initially describe and comparatively evaluate the morphology of the new Zhaoguo M1 upper limb remains, and contextualize upper limb functional adaptations among those of other worldwide Upper Paleolithic (UP) humans to make inferences about subsistence-related activity patterns in southwestern China at the Pleistocene-Holocene boundary. MATERIALS AND METHODS: The preserved Zhaoguo M1 skeletal remains include paired humeri, ulnae, and radii, among others. These specimens were scanned using micro-computed tomography to evaluate internal structural properties, while external osteometric dimensions of the Zhaoguo M1 upper limb elements also were acquired. Both sets of measurements were compared to published data on Neandertals, and Middle and Upper Paleolithic modern humans. RESULTS: The upper limb elements of Zhaoguo M1 display a suite of characteristics that generally resemble those of other contemporary Late UP (LUP) modern humans, while robusticity indices generally fall within the upper range of LUP variation. The Zhaoguo M1 upper limb elements display fewer traits resembling those of late archaic humans. The Zhaoguo M1 individual exhibits diaphyseal asymmetry in several upper limb elements suggesting left hand dominance. When evaluating the full range of magnitudes of humeral bilateral asymmetry in the comparative sample, Zhaoguo M1 falls at the lower end overall, but yet is relatively higher than contemporary LUP modern humans specifically from East Eurasia. DISCUSSION: The Zhaoguo M1 individual suggests typical LUP modern human upper limb morphology persisted in southwest China until the end of the last glacial period. Upper limb bone asymmetry of Zhaoguo M1 also indicates that behavioral activities attributed to a hunter-gatherer tradition apparently extended through the Pleistocene-Holocene transition in this region.

A bioarchaeological approach to the reconstruction of changes in military organization among Iron Age Samnites (Vestini) From Abruzzo, Central Italy.

The Samnites were an Iron Age population that shifted from warlike mountain dwellers to the largest sociopolitical unit of central Italy, able to dispute with Rome the domination over the peninsula. Archaeological and historical evidence suggests that this major shift in the scale of conflict may have involved a reorganization of the military system, which changed from an elite militia to a conscript or standing army from the Orientalizing-Archaic (800-500 BC) to Hellenistic times (400-27 BC). We propose a bioarchaeological framework jointly analyzing skeletal properties and funerary treatment in male Samnites to investigate on this shift in military organization. We anticipated that, when Samnites had an elite militia, the warring force was constituted by the wealthier segments of the society. Conversely, we expected the warring force of the standing/conscript army to be mainly drawn from the lower social strata. We considered high asymmetry in J, a measure of humeral torsional rigidity (calculated via cross-sectional geometry, CSG) as a proxy for pre- and peri-adolescent-onset weapon training. The social standing of the individual was approximated via funerary treatment analysis (Status Index). Results show that in the Orientalizing-Archaic period, humeral asymmetry and Status Index are positively correlated, and the high-status subsample shows significantly higher asymmetry than the low-status subsample. Among Hellenistic Samnites, no correlation between Status Index and humeral asymmetry is present, and the low-status subsample is the most lateralized. Results support the use of CSG in a strong theoretical framework to investigate past changes in military organization and their correlates in terms of sociopolitical development, alterations of power relationships, and warfare.

Archery's signature: an electromyographic analysis of the upper limb.

Non-technical summary: Bow and arrow technology plays a significant role in the recent evolutionary history of modern humans, but limitations of preservation make it challenging to identify archaeological evidence of early archery. Since bone structure can change in response to muscle force, archers of the past can potentially be identified through analysis of upper arm bones. However, there is limited research on how archery impacts upper limb musculature. This study offers initial insights into how archery impacts humeral musculature and highlights the need for additional research focused on archery's direct impact on humeral morphology. Technical summary: Humeral morphology has been used to support behaviour reconstructions of archery in past populations. However, the lack of experimental research concerning the impacts that archery has on the upper limb weakens skeletal morphological approaches. The goal of this study was to determine how archery impacts the activation of upper limb musculature. More specifically, this study tested: (a) whether the relative muscle activations are similar between arms; and (b) what muscles were activated on the dominant (draw) arm compared with the non-dominant (bow) arm. Data on upper arm muscle activation were collected bilaterally for nine archers using surface electromyography (EMG). Results show similar levels of muscle activation bilaterally with different muscles being activated in each arm. There were significantly higher integrated EMG and peak muscle activations of the biceps brachii muscles in the draw arm compared with the bow arm. In contrast, the lateral deltoid and the triceps brachii muscles had significantly higher integrated EMG and peak muscle activations on the bow arm compared with the draw arm. This work offers initial insights into how archery impacts humeral musculature and highlights the need for additional research focused on archery's direct impact on humeral morphology.