Revisiting East–West Skull Patterns and the Role of Random Factors in South America: Cranial Reconstruction and Morphometric Analysis of the Facial Skeleton from Cuncaicha Rockshelter (Southern Peru)

ABSTRACT

The aim of this paper is to evaluate the craniometric affinities of the only Cuncaicha cranial specimen with other early, middle, and late Holocene South American samples. To do so, the skull was first reconstructed by using computer-aided techniques applied to several μ-CT-scanned fragments. Linear measurements were calculated in the facial skeleton and compared to specimens from a previously available database. We conducted Principal Component and Discriminant Analysis, calculated Mahalanobis distances to evaluate the similarities of the Cuncaicha specimen with early/middle Holocene samples from South America, and estimated a Δ statistic for testing the neutral hypothesis among Peruvian samples. The results show that Cuncaicha presents shape similarities with Lagoa Santa and Lauricocha, mostly in masticatory and respiratory components. Finally, directional selection explains most of the diversification of Peruvian populations. We discuss our results in the context of migratory pathways, as well as the evolutionary processes behind human diversification in the Americas.

KEYWORDS:

• Cranial variation
• early Holocene Andean populations
• computer-aided techniques for cranial reconstruction
• square Mahalanobis distances (D²)
• Lynch test (Δ)

Acknowledgements

This paper is dedicated to the memory of Professor Pucciarelli, who has been a huge inspiration by being both a remarkable professor and very kind person who contributed significantly to the development of biological anthropology in South America. We would like to thank Federico Restifo and Rodolphe Hoguin for organizing the Symposium “The peopling of the Andes: Updating and New Contributions” at the XVIII UISPP World Congress in Paris, as well as for inviting us to publish our results as part of this special volume. Special thanks to Nora Flegenheimer, who helped us during the evaluation and editorial process. Additionally, we are very grateful to Professor Joachim Wahl, who helped with the identification of some very small cranial fragments. We would like to thank Maria Clara Lopez Sosa for contributing with contextual information of the comparative database; Hugo Reyes-Centeno and Abel Bosman for scanning the Cuncaicha material; Antonio Profico, Abel Bosman, and Carolin Roeding for sharing their experiences on virtual reconstruction; and Judith Beier and Michael Francken, who provided information regarding the recovering of the skeletons during the Cuncaicha excavations. Finally, we are very thankful to Mark Hubbe, who facilitated the code for calculating Mahalanobis distances in R. Scanning of the Cuncaicha skeletal material was made possible through a Deutsche Forschungsgemeinschaft major instrumentation grant (DFG INST 37/706-1). This research was funded by the DFG Centre for Advanced Studies “Words, Bones, Genes, Tools” (DFG FOR 2237), directed by Katerina Harvati, and by the “Bridging Funds” Program of the University of Tübingen granted to Lumila Menéndez. Cuncaicha field and laboratory work was supported by an Alexander von Humboldt Foundation fellowship (K.R.), the DFG (FOR 2237, INST 37/706), the Pontifical Catholic University of Lima, and Northern Illinois University. Finally, we would like to thank three anonymous reviewers who helped us to improve an earlier version of this manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Lumila Menéndez is a bioanthropologist who received her PhD in 2014 at Universidad Nacional de La Plata, Argentina. She is currently a postdoctoral fellow at the Konrad Lorenz Institute for Evolution and Cognition Research in Klosterneuburg, Austria. She conducted this research during her fellowship at the DFG Centre for Advanced Studies “Words, Bones, Genes, Tools”, at the University of Tübingen, Germany. Her research focuses on studying human evolution by disentangling the evolutionary processes that acted during the diversification of South American populations.

Kurt Rademaker is an archaeologist who received his PhD in 2012 at the University of Maine, USA. He is an Assistant Professor in the Department of Anthropology at Michigan State University. His research includes the investigation of early archaeological sites and paleoenvironments in Andean South America to understand human-environment dynamics and adaptations.

Katerina Harvati is Professor for Paleoanthropology at the University of Tübingen. She received her PhD from the City University of New York Graduate Center/New York Consortium for Evolutionary Primatology (NYCEP) in 2001. Her research interests include Pleistocene human evolution and diversification, the interplay between skeletal phenotype, genetics and environmental factors, and the dispersal of Homo sapiens around the globe. She currently directs the DFG Centre of Advanced Studies “Bones, Words, Genes, Tools: Tracking linguistic, cultural and biological trajectories of the human past” and the ERC Consolidator project “Human Evolution at the Crossroads”.

ORCID

Lumila Paula Menéndez http://orcid.org/0000-0002-7867-2910

Kurt Rademaker http://orcid.org/0000-0001-5676-4884

Additional information

Funding

This work was supported by Eberhard Karls Universität Tübingen (DE ): [Grant Number Bridging Funds]; Deutsche Forschungsgemeinschaft (DFG): [Grant Number DFG FOR 2237].