{
  "id": 1733498,
  "title": "Double spiral inside narwhal tusks may explain their resistance to bending",
  "url": "https://urgent.news/2026/08/18/double-spiral-inside-narwhal-tusks-may-explain-their-resistance-to",
  "topic": "science",
  "section": "Science",
  "published": "2026-08-18T15:00:08.000Z",
  "source": {
    "name": "Phys.org",
    "slug": "phys-org",
    "url": "https://phys.org/news/2026-08-spiral-narwhal-tusks-resistance.html"
  },
  "original_language": "en",
  "account": "A recent study published in Nature Communications has revealed an intriguing double-spiral structure within narwhal tusks, offering insights into their remarkable strength and resistance to bending. The narwhal, known for its long, white, spiraled tusk, has long been shrouded in mystery, with its purpose debated by researchers. Now, an international team of scientists has used advanced 3D X-ray techniques to uncover the tooth's unique composition.\n\nThe researchers discovered that the narwhal tusk consists of two opposing spirals, one twisting to the left and the other to the right, effectively creating a biological counterbalance. This dual-spiral structure, formed by mineralized collagen fibrils, provides the tusk with exceptional stability against bending and twisting forces. The outer cementum layer contains a left-handed spiral, while the inner dentin layer forms a right-handed spiral, with the two structures meeting at the boundary between dentin and cementum.\n\nThe discovery was made possible through the collaboration of chemists, physicists, materials scientists, and biologists, utilizing three powerful synchrotron X-ray sources in Sweden, Switzerland, and France. The technique, called tensor tomography, allowed the researchers to analyze the X-ray scattering patterns from the nanoscale mineralized collagen fibrils, revealing the intricate three-dimensional orientation of the building blocks within the tooth.\n\nInterestingly, the double-spiral structure is consistent throughout the tusk's annual growth layers, suggesting a genetically programmed growth pattern that remains stable throughout the narwhal's life, which can span up to 80 years. This finding not only solves a centuries-old mystery about the narwhal's tusk but also provides valuable insights into how nature constructs advanced materials with extreme mechanical properties. These findings may inspire the development of new composite materials for various applications, including construction and medicine.\n\nWhile the primary purpose of the narwhal tusk remains debated, the researchers speculate that it could serve as a sexual signal, a temperature and salinity detector, or a hunting tool, although no definitive evidence has been found to support these theories. The study also highlights the potential of examining narwhal tusks as historical records of environmental changes over an animal's lifetime, particularly in the context of the rapidly changing North Atlantic.",
  "summary": "The narwhal's impressive tusk has long been the subject of myths. In the Middle Ages, they were sold as unicorn horns believed to possess magical powers. Now, an international team of researchers led by Aarhus University has solved the mystery of how the tusk acquires its twisted structure.",
  "key_points": [
    "Narwhal tusks have double-spiral structure, left-handed and right-handed.",
    "Tensor tomography reveals nanoscale mineralized collagen fibrils orientation.",
    "Structure provides exceptional stability against bending and twisting forces."
  ],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}