Universally ouchy

Subjects Applied physicsBiomechanicsMechanical properties Access through your institution Buy or subscribe Pointed structures in nature, from narwhal tusks to spines on single-celled organisms, share a universal shape dictated by a power law. Recently, this universality has been attributed to evolutionary advantage. Now, John Sebastian and Kaare Jensen have argued (Proc. Natl Acad. Sci. USA 123, e2526098123; 2026) that the common profile can instead arise from mechanical wear.Sebastian and Jensen investigated whether mechanical processes could produce the universal parabolic shape. As substitutes for biological points experiencing natural wear, they used pencils on a vibrating plate. Collsions between the tips and other pencils eventually wore down their initial shape to the universal form. This happened for pencils of different hardnesses, with different initial shapes, and for a pencil-shaped analogue made from bull horn. This is a preview of subscription content, access via your institution Access options Access through your institution Access Nature and 54 other Nature Portfolio journals Get Nature+, our best-value online-access subscription $32.99 / 30 days cancel any time Learn more Subscribe to this journal Receive 12 print issues and online access $259.00 per year only $21.58 per issue Learn more Rent or buy this article Prices vary by article type from$1.95 to$39.95 Learn more Prices may be subject to local taxes which are calculated during checkout Author informationAuthors and AffiliationsNature Physics https://www.nature.com/nphys/Richard BrierleyAuthorsRichard BrierleyView author publicationsSearch author on:PubMed Google ScholarCorresponding authorCorrespondence to Richard Brierley.Rights and permissionsReprints and permissionsAbout this articleCite this articleBrierley, R. Universally ouchy. Nat. Phys. (2026). https://doi.org/10.1038/s41567-026-03269-5Download citationPublished: 16 April 2026Version of record: 16 April 2026DOI: https://doi.org/10.1038/s41567-026-03269-5Share this articleAnyone you share the following link with will be able to read this content:Get shareable linkSorry, a shareable link is not currently available for this article.Copy shareable link to clipboard Provided by the Springer Nature SharedIt content-sharing initiative