The impact of subsistence changes on humeral bilateral asymmetry in Terminal Pleistocene and Holocene Europe

Abstract

Analyses of upper limb bone bilateral asymmetry can shed light on manipulative behavior, sexual division of labor, and the effects of economic transitions on skeletal morphology. We compared the maximum (absolute) and directional asymmetry in humeral length, articular breadth, and cross-sectional diaphyseal geometry (CSG) in a large (n > 1200) European sample distributed among 11 archaeological periods from the Early Upper Paleolithic through the 20(th) century. Asymmetry in length and articular breadth is right-biased, but relatively small and fairly constant between temporal periods. Females show more asymmetry in length than males. This suggests a low impact of behavioral changes on asymmetry in length and breadth, but strong genetic control with probable sex linkage of asymmetry in length. Asymmetry in CSG properties is much more marked than in length and articular breadth, with sex-specific variation. In males, a major decline in asymmetry occurs between the Upper Paleolithic and Mesolithic. There is no further decline in asymmetry between the Mesolithic and Neolithic in males and only limited variation during the Holocene. In females, a major decline occurs between the Mesolithic and Neolithic, with resulting average directional asymmetry close to zero. Asymmetry among females continues to be very low in the subsequent Copper and Bronze Ages, but increases again in the Iron Age. Changes in female asymmetry result in an increase of sexual dimorphism during the early agricultural periods, followed by a decrease in the Iron Age. Sexual dimorphism again slightly declines after the Late Medieval. Our results indicate that changes in manipulative behavior were sex-specific with a probable higher impact of changes in hunting behavior on male asymmetry (e.g., shift from unimanual throwing to use of the bow-and-arrow) and food grain processing in females, specifically, use of two-handed saddle querns in the early agricultural periods and one-handed rotary querns in later agricultural periods.

Low trabecular bone density in recent sedentary modern humans

“…The lack of clear distinctions in the type of tools used is a constraining factor in interpretation of our data and therefore, we use generalized levels of activity to interpret the results. Another factor increasing variability in upper limb bone structure is bilateral asymmetry in behavioral use, which also varies between populations (Auerbach and Ruff, ; Sládek et al, ). Because of sampling limitations (due to poor preservation, pathological cases or missing elements, see Supporting Information Table S1), we included both right and left upper limb elements in this study, which likely also increased variation, although we found no significant difference between right and left sides.…”

The effect of diet and sociopolitical change on physiological stress and behavior in lateRoman‐EarlyByzantine (300–700AD) and Islamic (902–1,235AD) populations from Ibiza, Spain

“…Averaging is further not likely to bias analysis, because lower limb dimensions have limited asymmetry (Auerbach & Ruff, 2006). Given the potential for asymmetric loading due to handedness, left and right humeral diaphyseal products and circumference were analyzed separately, though comparisons of average values are also reported (Auerbach & Ruff, 2006; Sládek et al, 2016). Results from average values agreed with patterns seen in left and right elements.…”

Humeral laterality in modern humans and Neanderthals: a 3D geometric morphometric analysis

“…They concluded that in men diaphyseal dimensions and vertical head diameter are more asymmetric, while in women the humeral length is more asymmetric. Despite differences between the two studies, the laterality pattern could be associated with different activity patterns related to the different manipulative behaviors of the sexes (Sládek et al, 2007(Sládek et al, , 2016. In this work, we have observed through 3DGM that the female mean shape presents higher laterality differences than in males.…”

“…Considering all of this, the dominant hand is associated with a larger size and greater development of MSMs in the corresponding arm. The dominance of the right arm has been observed in different osteological populations of Homo sapiens, including recent hunter-gatherers, medieval British and Slovenes, the Romano-British population, German Neolithic farmers, Central European Late Eneolithic peoples, and Early Bronze Age and Northern European Mesolithic peoples (Schultz, 1937;Thould and Thould, 1983;Constandse-Westermann and Newell, 1989;Reichel et al, 1990;Trinkaus et al, 1994;Steele and Mays, 1995;Churchill and Formicola, 1997;Wilczak, 1998;Mays, 1999;Cuk et al, 2001;Lazenby, 2002;Auerbach and Ruff, 2006;Sládek et al, 2007Sládek et al, , 2016Weiss, 2009;Blackburn, 2011).…”