A study of 12 primate teeth spanning nearly 18 million years reveals that tooth enamel nanocrystals become more misoriented when diets get harder, including when early humans started eating meat and later adopted agriculture.
Published in Nature, the research used a novel imaging method called PELICAN to measure the angular mismatch between adjacent hydroxyapatite nanocrystals in enamel. The team analyzed teeth from fossil and living apes, monkeys, and hominins, including Paranthropus boisei, early Homo, and modern humans.
The results show that a nut‑cracking monkey (Cercocebus atys) has the highest misorientation angle (7.2°), while fruit‑eating chimpanzees have the lowest (1.3°). Among human ancestors, the shift to meat‑eating about 1.5–2.0 million years ago correlated with a jump in misorientation from ~2.1° to ~3.5°. The later transition to agriculture (~12,000 years ago) nearly doubled misorientation to ~4.7°, a value that remained stable through the Industrial Revolution.
“Greater misorientation likely makes enamel tougher by deflecting cracks,” said co‑author Pupa Gilbert. The team found no significant link between misorientation and tooth size, bite force, or wear—pointing directly to diet as the driver.
The discovery adds a nanoscale dimension to how teeth evolve under dietary pressure and could inspire tougher bioinspired materials. “Even small misorientation angles, below 15°, create low‑energy boundaries that hinder crack propagation,” the authors note.
The study highlights that two major dietary shifts in human evolution, meat and grain‑based agriculture, left a permanent crystallographic signature in our teeth.
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Reference
Gilbert, P.U.P.A., Green, D.R., Mahoney, P. et al. Enamel nanocrystal misorientation increased with meat-eating and agriculture. Nature 654, 76–84 (2026). https://doi.org/10.1038/s41586-026-10583-8
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