News release

From: Springer Nature

Materials science: Changes in enamel structure alongside human diets

Tooth enamel structure changed at the nanoscale as the human diet shifted toward meat and agriculture products over the past two million years, according to an analysis published in Nature. The findings uncover a possible mechanism that underlies enamel resistance, which may have implications for increasing the strength and resilience of bioinspired materials.

Enamel thickness and shape have been shown to evolve with changes in diet. Enamel consists of long nanocrystals of a mineral called hydroxyapatite — about 50 to 70 nanometres wide — which can vary in orientation. However, how these structural changes are related to diet and enamel resilience is poorly understood.

Pupa Gilbert and authors analysed tooth samples spanning almost 18 million years, including ancient primates and humans, as well as modern humans. The authors found an increase in enamel nanocrystal misorientation over the past 1.76 million years of Homo evolution as meat and agriculture became more common dietary staples. This change was notable as diets shifted with an increase in grain-based agriculture in Europe, which began 12,000 years ago. The authors found no evidence of further misorientation during the Industrial Revolution, although increases in cavities and dental crowding are documented consequences of industrialised diets. In an analysis of teeth from non-human apes and monkeys, those species that consumed fruit primarily saw the lowest misorientation, while species that consumed seeds saw the highest misorientation.

The authors conclude that nanocrystal misorientation could contribute to tooth resilience against tough or hard foods, such as meat and seeds. They suggest that misorientation of enamel could contribute to its resilience, which could influence the synthesis of bioinspired materials.