Fossil teeth from early human ancestors show fewer scratches over time, suggesting their diets became softer, possibly because they started using better stone tools or cooking food with fire.
Mechanism
Synthesis from 1 study
When early humans started using tools to cut food or fire to soften it, they removed the gritty bits and tough bits that used to scrape their teeth. With less grit in their food, their teeth got fewer scratches over time, which is what we see in the fossil record.
Most probable mechanism
When food is softened or cleaned of grit before eating—through tools or heat—the particles that scrape against teeth during chewing become fewer and less harsh. This means the enamel on the outer surfaces of back teeth gets fewer scratches over time, because the forces acting on them are smaller and less frequent.
Food is mechanically processed or thermally altered before ingestion, reducing the presence of hard, abrasive particles such as quartz grit, silica phytoliths, or bone fragments.
During mastication, the reduced number and hardness of food particles generate lower mechanical forces on the buccal enamel surfaces, below the threshold needed to produce dense scratching.
The reduced abrasive load results in fewer indentations and shearing events on the enamel surface during chewing, limiting the formation of linear microscratches.
Over time, the cumulative absence of high-frequency abrasive events leads to a measurable decline in scratch density on the buccal enamel of posterior teeth.
Evidence from Studies
Supporting (1)
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The diet of the first Europeans from Atapuerca
Contradicting (0)
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