Computed tomography shows high fracture prevalence among physically active forager-horticulturalists with high fertility
Abstract
Modern humans have more fragile skeletons than other hominins, which may result from physical inactivity. Here we test whether reproductive effort also compromises bone strength, by measuring using computed tomography thoracic vertebral bone mineral density (BMD) and fracture prevalence among physically active Tsimane forager-horticulturalists. Earlier onset of reproduction and shorter interbirth intervals are associated with reduced BMD for women. Tsimane BMD is lower versus Americans, but only for women, contrary to simple predictions relying on inactivity to explain skeletal fragility. Minimal BMD differences exist between Tsimane and American men, suggesting that systemic factors other than fertility (e.g. diet) do not easily explain Tsimane women's lower BMD. Tsimane fracture prevalence is also higher versus Americans. Lower BMD increases Tsimane fracture risk, but only for women, suggesting a role of weak bone in women's fracture etiology. Our results highlight the role of sex-specific mechanisms underlying skeletal fragility that operate long before menopause.
Data availability
The data that support the findings of this study are available on Dryad (http://dx.doi.org/10.5061/dryad.rf0g0md).
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Data from: Computed tomography shows high fracture prevalence among physically active forager-horticulturalists with high fertilityDryad Digital Repository, doi:10.5061/dryad.rf0g0md.
Article and author information
Author details
Funding
National Institutes of Health (R01AG024119)
- Jonathan Stieglitz
- Benjamin C Trumble
- Caleb Finch
- Hillard Kaplan
- Michael Gurven
Arizona State University
- Benjamin C Trumble
University of California, Santa Barbara
- Michael Gurven
Agence Nationale de la Recherche (ANR-17-EURE-0010)
- Jonathan Stieglitz
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Human subjects: Institutional IRB approval was granted by UNM (HRRC # 07-157) and UCSB (# 3-16-0766), as was informed consent at three levels: (1) Tsimane government that oversees research projects, (2) village leadership and (3) study participants.
Copyright
© 2019, Stieglitz et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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