1. Evolutionary Biology
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Computed tomography shows high fracture prevalence among physically active forager-horticulturalists with high fertility

  1. Jonathan Stieglitz  Is a corresponding author
  2. Benjamin C Trumble
  3. HORUS Study Team
  4. Caleb Finch
  5. Dong Li
  6. Matthew J Budoff
  7. Hillard Kaplan
  8. Michael Gurven
  1. Universite Toulouse 1 Capitole, France
  2. Arizona State University, United States
  3. University of Southern California, United States
  4. Emory University, United States
  5. University of California, Los Angeles, United States
  6. Chapman University, United States
  7. University of California, Santa Barbara, United States
Research Article
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Cite this article as: eLife 2019;8:e48607 doi: 10.7554/eLife.48607

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).

The following data sets were generated

Article and author information

Author details

  1. Jonathan Stieglitz

    Institute for Advanced Study in Toulouse, Universite Toulouse 1 Capitole, Toulouse, France
    For correspondence
    jonathan.stieglitz@iast.fr
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-5985-9643
  2. Benjamin C Trumble

    Arizona State University, Tempe, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. HORUS Study Team

  4. Caleb Finch

    University of Southern California, Los Angeles, United States
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-7617-3958
  5. Dong Li

    Emory University, Atlanta, United States
    Competing interests
    The authors declare that no competing interests exist.
  6. Matthew J Budoff

    University of California, Los Angeles, Los Angeles, United States
    Competing interests
    The authors declare that no competing interests exist.
  7. Hillard Kaplan

    Chapman University, Orange, United States
    Competing interests
    The authors declare that no competing interests exist.
  8. Michael Gurven

    University of California, Santa Barbara, Santa Barbara, United States
    Competing interests
    The authors declare that no competing interests exist.

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.

Reviewing Editor

  1. Diethard Tautz, Max-Planck Institute for Evolutionary Biology, Germany

Publication history

  1. Received: May 20, 2019
  2. Accepted: August 14, 2019
  3. Accepted Manuscript published: August 16, 2019 (version 1)
  4. Version of Record published: September 4, 2019 (version 2)
  5. Version of Record updated: September 9, 2019 (version 3)

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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