Abstract
Objectives: Lower thoracic widths and curvatures track upper pelvic widths and iliac blades curvatures in hominins and other primates (torso integration hypothesis). However, recent studies suggest that sexual dimorphism could challenge this assumption in Homo sapiens. We test the torso integration hypothesis in two modern human populations, both considering and excluding the effect of sexual dimorphism. We further assess covariation patterns between different thoracic and pelvic levels, and we explore the allometric effects on torso shape variation. Material and Methods: A sex-balanced sample of 50 anatomically connected torsos (25 Mediterraneans, 25 Sub-Saharan Africans) was segmented from computed tomography scans. We compared the maximum medio-lateral width at seventh–ninth rib levels with pelvic bi-iliac breadth in males and females within both populations. We measured 1,030 (semi)landmarks on 3D torso models, and torso shape variation, mean size and shape comparisons, thoraco-pelvic covariation and allometric effects were quantified through 3D geometric morphometrics. Results: Females show narrow thoraces and wide pelves and males show wide thoraces and narrow pelves, although this trend is more evident in Mediterraneans than in Sub-Saharans. Equal thoracic and pelvic widths, depths and curvatures were found in absence of sexual dimorphism. The highest strength of covariation was found between the lowest rib levels and the ilia, and allometric analyses showed that smaller torsos were wider than larger torsos. Conclusions: This is the first study testing statistically the torso integration hypothesis in anatomically connected torsos. We propose a new and more complex torso integration model in H. sapiens with sexual dimorphism leading to different thoracic and pelvic widths and curvatures. These findings have important implications in hominin body shape reconstructions.
| Original language | English |
|---|---|
| Pages (from-to) | 777-790 |
| Number of pages | 14 |
| Journal | American Journal of Physical Anthropology |
| Volume | 167 |
| Issue number | 4 |
| DOIs | |
| State | Published - Dec 2018 |
Bibliographical note
Publisher Copyright:© 2018 Wiley Periodicals, Inc.
Funding
The authors also thank Dr. Jacqueline S. Smilg of the School of Radiation Sciences (University of the Witwatersrand Medical School, Johannesburg, South Africa) and Department of Radiology of the Charlotte Maxeke Academic Hospital (Johannesburg, South Africa) for technical support during the CT-data collection; the Sackler Faculty of Medicine (Tel Aviv University, Israel) for allowing access to the material from Israel; and ERESA (Exploraciones Radiológicas Especiales) for allowing access to the Spanish CT data. The authors are grateful to Dr. Stefan Schlager (Department of Biological Anthropology, University of Freiburg) for guidance and inexhaustible patience during the process of learning Morpho 2.6 package and to Dr. Dean Adams, Dr. Mike Collyer and Dr. Antigoni Kaliontzopoulou for their willingness to clarify statistical issues. Finally, the authors thank Anabel Fer-rando and Dr. Benoît Beyer, who contributed their time with helpful comments, and two anonymous reviewers and the associate editor, whose suggestions helped improve and clarify this manuscript. This research is funded by CGL-2015-63648-P (Ministry of Economy, Industry and Competitiveness, Spain). information Ministerio de Econom?a y Competitividad, Grant/Award Number: CGL-2015-63648-P; Ministry of Economy, Industry and Competitiveness, Grant/Award Number: CGL-2015-63648-PThe authors thank the Virtual Morphology Lab (MNCN-CSIC) for support and Pedro Osborne M?rquez for 3D postprocessing assistance. The authors also thank Dr. Jacqueline S. Smilg of the School of Radiation Sciences (University of the Witwatersrand Medical School, Johannesburg, South Africa) and Department of Radiology of the Charlotte Maxeke Academic Hospital (Johannesburg, South Africa) for technical support during the CT-data collection; the Sackler Faculty of Medicine (Tel Aviv University, Israel) for allowing access to the material from Israel; and ERESA (Exploraciones Radiol?gicas Especiales) for allowing access to the Spanish CT data. The authors are grateful to Dr. Stefan Schlager (Department of Biological Anthropology, University of Freiburg) for guidance and inexhaustible patience during the process of learning Morpho 2.6 package and to Dr. Dean Adams, Dr. Mike Collyer and Dr. Antigoni Kaliontzopoulou for their willingness to clarify statistical issues. Finally, the authors thank Anabel Ferrando and Dr. Beno?t Beyer, who contributed their time with helpful comments, and two anonymous reviewers and the associate editor, whose suggestions helped improve and clarify this manuscript. This research is funded by CGL-2015-63648-P (Ministry of Economy, Industry and Competitiveness, Spain).
| Funders | Funder number |
|---|---|
| Anabel Ferrando | |
| Department of Radiology of the Charlotte Maxeke Academic Hospital | |
| ERESA | |
| Sackler Faculty of Medicine | |
| University of the Witwatersrand Medical School, Johannesburg | |
| Virtual Morphology Lab | |
| Albert-Ludwigs-Universität Freiburg | |
| Ministry of Economy, Trade and Industry | |
| Ministerio de EconomÃa y Competitividad | CGL-2015-63648-P |
| Tel Aviv University | |
| Ministerio de Asuntos Económicos y Transformación Digital, Gobierno de España |
Keywords
- allometry
- body shape
- geometric morphometrics
- sexual dimorphism
- torso