The narwhal tusk assembles its macroscopic helix from building blocks with opposing twists
Abstract Narwhal tusks are among the most intriguing structures in biology due to their immense size and unique left-handed helix. Whether this unique macroscopic homochirality originates in the structural arrangement of tusk building blocks has remained elusive. Therefore, we combined multiple structural techniques to reveal the hierarchical structure of the narwhal tusk from its building blocks (mineralized collagen fibrils) up to the macroscopic left-hand helix. Thus, we show that the macroscopic helical structure is reproduced from the molecular-scale arrangement of mineralized collagen in a double helix with opposite chirality. While mineralized collagen predominantly aligns along the tusk long axis, systematic axial deviations build helical arrangements of fibrils. Cementum has a left-hand helix of collagen fibrils, while dentine contains a right-hand arrangement extending across annual growth layers that feature distinct biomineral properties. This discovery advances understanding of how biological tissues integrate multiscale structural patterns to achieve specific mechanical and biological functions.
Authors
- Adrián Rodríguez-Palomo (ORCID: https://orcid.org/0000-0002-5497-4914)
- M. Burghammer
- Dimitra Athanasiadou (ORCID: https://orcid.org/0000-0001-9367-1572)
- Stefano Checchia (ORCID: https://orcid.org/0000-0003-0499-4885)
- Thorbjørn Erik Køppen Christensen (ORCID: https://orcid.org/0000-0002-0754-6984)
- Mads R. V. Jørgensen (ORCID: https://orcid.org/0000-0001-5507-9615)
- Marianne Liebi (ORCID: https://orcid.org/0000-0002-5403-0593)
- Leonard Nielsen (ORCID: https://orcid.org/0000-0002-5929-1127)
- Jonas Palle (ORCID: https://orcid.org/0000-0001-6126-4331)
- Karl Anker Jørgensen (ORCID: https://orcid.org/0000-0002-3482-6236)
- Henrik Birkedal (ORCID: https://orcid.org/0000-0002-4201-2179)
- Christian Appel (ORCID: https://orcid.org/0000-0002-6050-3836)
- Nina Kølln Wittig (ORCID: https://orcid.org/0000-0002-8394-5936)
- Jiliang Liu (ORCID: https://orcid.org/0000-0002-3491-3452)
- Mads Peter Heide‐Jørgensen (ORCID: https://orcid.org/0000-0003-4846-7622)
- Peter Alling Strange Vibe (ORCID: https://orcid.org/0000-0002-4556-3312)
- Innokenty Kantor (ORCID: https://orcid.org/0000-0001-5132-8354)
- Jonathan T. Avaro
- Eva Garde
Institutions
- Lund University (SE)
- Aarhus University (DK)
- European Synchrotron Radiation Facility (FR)
- Paul Scherrer Institute (CH)
- Sino-Danish Centre for Education and Research (CN)
- MAX IV Laboratory (SE)
- Grønlands Naturinstitut (GL)
- University of Chinese Academy of Sciences (CN)
- École Polytechnique Fédérale de Lausanne (CH)
- Chalmers University of Technology (SE)
- Swiss Federal Laboratories for Materials Science and Technology (CH)
- Technical University of Denmark (DK)
Publication Details
- Journal
- Nature Communications
- Published
- 2026-08-18
- DOI
- https://doi.org/10.1038/s41467-026-75689-z
- Primary Topic
- Collagen: Extraction and Characterization
- Type
- article
- Field-Weighted Citation Impact
- 0.00