Biocultural evidence of precise manual activities in an Early Holocene individual of the high-altitude Peruvian Andes.

Fotios Alexandros Karakostis,Michael Franken,Gerhard Hotz,Katerina Harvati,Kurt Rademaker,Hugo Reyes‐Centeno

doi:10.1002/ajpa.24160

Abstract

Cuncaicha, a rockshelter site in the southern Peruvian Andes, has yielded archaeological evidence for human occupation at high elevation (4,480 masl) during the Terminal Pleistocene (12,500-11,200 cal BP), Early Holocene (9,500-9,000 cal BP), and later periods. One of the excavated human burials (Feature 15-06), corresponding to a middle-aged female dated to ~8,500 cal BP, exhibits skeletal osteoarthritic lesions previously proposed to reflect habitual loading and specialized crafting labor. Three small tools found in association with this burial are hypothesized to be associated with precise manual dexterity. Here, we tested this functional hypothesis through the application of a novel multivariate methodology for the three-dimensional analysis of muscle attachment surfaces (entheses). This original approach has been recently validated on both lifelong-documented anthropological samples as well as experimental studies in nonhuman laboratory samples. Additionally, we analyzed the three-dimensional entheseal shape and resulting moment arms for muscle opponens pollicis. Results show that Cuncaicha individual 15-06 shows a distinctive entheseal pattern associated with habitual precision grasping via thumb-index finger coordination, which is shared exclusively with documented long-term precision workers from recent historical collections. The separate geometric morphometric analysis revealed that the individual's opponens pollicis enthesis presents a highly projecting morphology, which was found to strongly correlate with long joint moment arms (a fundamental component of force-producing capacity), closely resembling the form of Paleolithic hunter-gatherers from diverse geo-chronological contexts of Eurasia and North Africa. Overall, our findings provide the first biocultural evidence to confirm that the lifestyle of some of the earliest Andean inhabitants relied on habitual and forceful precision grasping tasks.

Highlights

The biocultural evolution of Homo sapiens is characterized by environmental adaptability during dispersal across the world, which allowed early human populations to flourish across a diverse range of ecological conditions (Roberts & Stewart, 2018)
The separate geometric morphometric analysis revealed that the individual's opponens pollicis enthesis presents a highly projecting morphology, which was found to strongly correlate with long joint moment arms, closely resembling the form of Paleolithic hunter-gatherers from diverse geo-chronological contexts of Eurasia and North Africa
These findings demonstrate the presence of Terminal Pleistocene populations in a highly demanding environment, within ~2,000 years of the earliest lowland sites in South America

Summary

Introduction

The biocultural evolution of Homo sapiens is characterized by environmental adaptability during dispersal across the world, which allowed early human populations to flourish across a diverse range of ecological conditions (Roberts & Stewart, 2018). The dated occupational sequence of the site involves four different phases of human habitation, the oldest of which is dated to 12,500–11,200 cal BP These findings demonstrate the presence of Terminal Pleistocene populations in a highly demanding environment, within ~2,000 years of the earliest lowland sites in South America. Additional cranial elements belonging to this individual appear to have been translocated to a higher stratigraphic position ~4,000 cal BP when a seated burial was interred in Unit 13 atop individual 15-06 These cranial elements, including a mandible and molar that does not fit within the mandible, were assigned to individual 15-06 based on direct radiocarbon dates (Francken et al, 2018; Rademaker & Hodgins, 2018).

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