Scientists uncover how the narwhal's 10-foot tusk stays perfectly straight

Using powerful 3D X-ray scans at three European particle accelerators, scientists have mapped the internal architecture of the narwhal's singular, up-to-10-foot canine tooth. The analysis showed that the inner dentin spirals to the right and the outer cementum spirals to the left, creating opposing twists that counterbalance and keep the tusk straight as it emerges from the upper lip. Researchers also discovered concentric growth layers resembling tree rings, offering a potential chronological record of the animal's lifespan, which can reach about 80 years.

The tusks examined were sourced from Inuit hunters in Greenland and preserved museum specimens. Although the study clarifies the mechanical basis of the tusk's shape, scientists continue to debate its purpose, with theories ranging from social signaling among males to sensory functions. The findings, published in Nature Communications, provide a rare glimpse into a unique natural engineering solution.