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López-Rey JM, D'Angelo Del Campo MD, Seldes V, García-Martínez D, Bastir M. Eco-geographic and sexual variation of the ribcage in Homo sapiens. Evol Anthropol 2024:e22040. [PMID: 38951738 DOI: 10.1002/evan.22040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 06/19/2024] [Accepted: 06/21/2024] [Indexed: 07/03/2024]
Abstract
Up to now, Allen and Bergmann's rules have been studied in modern humans by analyzing differences in limb length, height, or body mass. However, there are no publications studying the effects of latitude in the 3D configuration of the ribcage. To assess this issue, we digitally reconstructed the ribcages of a balanced sample of 109 adult individuals of global distribution. Shape and size of the ribcage was quantified using geometric morphometrics. Our results show that the ribcage belonging to tropical individuals is smaller and slenderer compared to others living in higher latitudes, which is in line with Allen and Bergmann's rules and suggests an allometric relationship between size and shape. Although sexual dimorphism was observed in the whole sample, significant differences were only found in tropical populations. Our proposal is that, apart from potential sexual selection, avoiding heat loss might be the limiting factor for sexual dimorphism in cold-adapted populations.
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Affiliation(s)
- José M López-Rey
- Department of Paleobiology, Paleoanthropology Group, Museo Nacional de Ciencias Naturales (MNCN-CSIC), Madrid, Spain
- Laboratorio de Poblaciones del Pasado (LAPP), Department of Biology, Faculty of Sciences, Universidad Autónoma de Madrid (UAM), Madrid, Spain
| | - Manuel D D'Angelo Del Campo
- Laboratorio de Poblaciones del Pasado (LAPP), Department of Biology, Faculty of Sciences, Universidad Autónoma de Madrid (UAM), Madrid, Spain
- Consejo Nacional de Investigaciones Científicas y Técnicas, Centro Científico Tecnológico - Tandil (CONICET, CTT Tandil), Tandil, Argentina
- Laboratorio de Ecología Evolutiva Humana (LEEH), Facultad de Ciencias Sociales (FACSO), Unidad de Enseñanza Universitaria Quequén (UEUQ), Universidad Nacional del Centro de la Provincia de Buenos Aires (UNCPB), Quequén, Argentina
- Museo de Antropología, Instituto de Investigación Arqueológica y Antropológica (INIAA), Universidad Mayor, Real y Pontificia de San Francisco Xavier de Chuquisaca (UMRPSFXCH), Sucre, Bolivia
| | - Verónica Seldes
- Consejo Nacional de Investigaciones Científicas y Técnicas, Centro Científico Tecnológico - Tandil (CONICET, CTT Tandil), Tandil, Argentina
- Instituto de Ciencias Antropológicas, Sección de Antropología Biológica - Instituto de Arqueología, Facultad de Filosofía y Letras (FFYL), Universidad de Buenos Aires (UBA), Buenos Aires, Argentina
| | - Daniel García-Martínez
- Physical Anthropology Unit, Faculty of Biological Sciences, Universidad Complutense de Madrid (UCM), Madrid, Spain
- Department of Life Sciences, Laboratory of Forensic Anthropology, Center for Functional Ecology - Science for People and the Planet (CFE), Centre for Functional Ecology, University of Coimbra (UC), Calçada Martim de Freitas, Coimbra, Portugal
- Centro Nacional de Investigación sobre la Evolución Humana (CENIEH), Burgos, Spain
| | - Markus Bastir
- Department of Paleobiology, Paleoanthropology Group, Museo Nacional de Ciencias Naturales (MNCN-CSIC), Madrid, Spain
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Holcombe SA, Huang Y, Derstine BA. Population trends in human rib cross-sectional shapes. J Anat 2024; 244:792-802. [PMID: 38200705 PMCID: PMC11021607 DOI: 10.1111/joa.13999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 12/05/2023] [Accepted: 12/12/2023] [Indexed: 01/12/2024] Open
Abstract
Rib fractures remain the most frequent thoracic injury in motor vehicle crashes. Computational human body models (HBMs) can be used to simulate these injuries and design mitigation strategies, but they require adequately detailed geometry to replicate such fractures. Due to a lack of rib cross-sectional shape data availability, most commercial HBMs use highly simplified rib sections extracted from a single individual during original HBM development. This study provides human rib shape data collected from chest CT scans of 240 females and males across the full adult age range. A cortical bone mapping algorithm extracted cross-sectional geometry from scans in terms of local periosteal position with respect to the central rib axis and local cortex thickness. Principal component analysis was used to reduce the dimensionality of these cross-sectional shape data. Linear regression found significant associations between principal component scores and subject demographics (sex, age, height, and weight) at all rib levels, and predicted scores were used to explore the expected rib cross-sectional shapes across a wide range of subject demographics. The resulting detailed rib cross-sectional shapes were quantified in terms of their total cross-sectional area and their cortical bone cross-sectional area. Average-sized female ribs were smaller in total cross-sectional area than average-sized male ribs by between 20% and 36% across the rib cage, with the greatest differences seen in the central portions of rib 6. This trend persisted although to smaller differences of 14%-29% when comparing females and males of equal intermediate weight and stature. Cortical bone cross-sectional areas were up to 18% smaller in females than males of equivalent height and weight but also reached parity in certain regions of the rib cage. Increased age from 25 to 80 years was associated with reductions in cortical bone cross-sectional area (up to 37% in females and 26% in males at mid-rib levels). Total cross-sectional area was also seen to reduce with age in females but to a lesser degree (of up to 17% in mid-rib regions). Similar regions saw marginal increases in total cross-sectional area for male ribs, indicating age affects rib cortex thickness moreso than overall rib cross-sectional size. Increased subject height was associated with increased rib total and cortical bone cross-sectional areas by approximately 25% and 15% increases, respectively, in mid-rib sections for a given 30 cm increase in height, although the magnitudes of these associations varied by sex and rib location. Increased weight was associated with approximately equal changes in both cortical bone and total cross-sectional areas in males. These effects were most prominent (around 25% increases for an addition of 50 kg) toward lower ribs in the rib cage and had only modest effects (less than 12% change) in ribs 2-4. Females saw greater increases with weight in total rib area compared to cortical bone area, of up to 21% at the eighth rib level. Results from this study show the expected shapes of rib cross-sections across the adult rib cage and across a broad range of demographics. This detailed geometry can be used to produce accurate rib models representing widely varying populations.
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Affiliation(s)
- Sven A. Holcombe
- Morphomics Analysis GroupUniversity of MichiganAnn ArborMichiganUSA
| | - Yuan Huang
- Morphomics Analysis GroupUniversity of MichiganAnn ArborMichiganUSA
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