Overview
- The Nature Communications paper published Tuesday confirms the tusk is built from two helices: an outer left‑handed cementum spiral and an inner right‑handed dentin spiral.
- Scientists mapped the tusk in 3D across atomic to macroscales using tensor tomography, scanning X‑ray diffraction and small‑angle scattering at three European synchrotrons.
- Mechanical tests and structural maps show the opposing helices produce high stiffness and resistance to bending and twisting, which explains how a tusk can grow straight over decades.
- Analyses of museum and Greenlandic Inuit‑collected specimens revealed annual growth layers that preserve roughly an 80‑year life record and will be used to trace individual life history and environmental change.
- The study reframes questions about tusk function but does not settle them because authors favor a sexual‑selection role while other experts continue to argue for a sensory function, and the team plans follow‑up work on growth rings and the skull attachment site.