Divergence in Male and Female Manipulative Behaviors with the Intensification of Metallurgy in Central Europe

Abstract

Humeral morphology has been shown to reflect, in part, habitual manipulative behaviors in humans. Among Central European agricultural populations, long-term social change, increasing task specialization, and technological innovation all had the potential to impact patterns of habitual activity and upper limb asymmetry. However, systematic temporal change in the skeletal morphology of agricultural populations in this region has not been well-characterized. This study investigates diachronic patterns in humeral biomechanical properties and lengths among 174 adult Central European agriculturalists through the first ∼5400 years of farming in the region. Greater asymmetry in biomechanical properties was expected to accompany the introduction of metallurgy, particularly in males, while upper limb loading patterns were expected to be more similar between the Bronze and Iron Ages. Results revealed a divergence in the lateralization of upper limb biomechanical properties by sex between the Early/Middle Neolithic and Early/Middle Bronze Age. Neolithic females had significantly more variable properties than males in both humeri, while Bronze Age female properties became homogeneous and very symmetrical relative to the right-biased lateralization of contemporaneous males. The Bronze Age to Iron Age transition was associated with morphological change among females, with a significant increase in right-biased asymmetry and a concomitant reduction in sexual dimorphism. Relative to biomechanical properties, humeral length variation and asymmetry were low though some significant sexual dimorphism and temporal change was found. It was among females that the lateralization of humeral biomechanical properties, and variation within them, changed most profoundly through time. This suggests that the introduction of the ard and plow, metallurgical innovation, task specialization, and socioeconomic change through ∼5400 years of agriculture impacted upper limb loading in Central European women to a greater extent than men.

Fluctuating Asymmetry of Human Populations: A Review

“…Directional asymmetry can inflate estimates of fluctuating asymmetry, even when some indices that purport to remove it are used [48]. Long bones of the upper limbs, for example, have a right bias in most populations [49][50][51]. Furthermore, parts of the cranial skeleton can also be directionally asymmetric [32,52,53].…”

“…Mechanical loading through tool use, for example, can exacerbate directional asymmetry of the upper limbs. Macintosh et al [51], for example, have inferred that changes in the upper limb asymmetry of women from the Bronze Age to the Iron Age were caused by the introduction and use of the ard and plow in agriculture.…”

Lower limb biomechanics and habitual mobility among mid-Holocene populations of the Cis-Baikal

“…Variation in long bone robusticity has frequently been used to infer patterns of activity in the past (Ruff et al, 1984;Bridges, 1989;Stock, 2006;Macintosh et al, 2014a), with particular emphasis on the relationship between lower limb robusticity and terrestrial mobility (Ruff, 1987(Ruff, , 1994Larsen, 1995;Holt, 2003;Stock and Pfeiffer, 2004;Stock, 2006;Stock et al, 2011;Pomeroy, 2013;Shaw and Stock, 2013;Davies et al, 2014;Macintosh et al, 2014b). Comparisons of lower limb robusticity across cultural transitions in North America have noted that femoral diaphyses among agricultural populations tend to be more circular with smaller total subperiosteal areas, which suggests decreased mobility following the adoption of agriculture (Ruff et al, 1984;Ruff, 1987;Ruff and Larsen, 1990).…”

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

“…One clue to human manipulative behavior in the past can be derived from assessments of handedness and upper limb bone bilateral asymmetry (e.g., Bridges, 1985Bridges, , 1989Bridges, , 1991Constandse-Westermann and Newell, 1989;Fresia et al, 1990;Trinkaus et al, 1994;Churchill et al, 1996;Albert and Greene, 1999;Trinkaus and Churchill, 1999;Ledger et al, 2000;Stock andPfeiffer, 2001, 2004;Weiss, 2003;Rhodes and Knüsel, 2005;Auerbach and Ruff, 2006;Marchi et al, 2006;Sládek et al, 2007;Kujanová et al, 2008;Stock et al, 2013;Macintosh et al, 2014;Sparacello et al, 2015). Bilateral skeletal asymmetry in the upper limb bones is significant among past and recent humans because the upper limb is directly influenced by the lateralized effect of manipulation and is free from the relatively symmetrical loading of the lower limbs associated with bipedal locomotion .…”

“…First, the major change in subsistencerelated activities for males may have occurred in conjunction with the reduction of hunting after the Upper Paleolithic. Second, unilateral activities associated with hunting may have been replaced, in part, by other activities with similar unilateral loading patterns, such as the crafting of stone hatchets and woodworking (Sparacello et al, 2011), metallurgy (Macintosh et al, 2014), and warfare (Sparacello et al, 2015). The increased reliance on agricultural subsistence during the Holocene was accompanied by other processes, such as economic specialization and increased social complexity.…”