Tooth enamel originated from fish scales, study finds

Enamel may have evolved from the scales and colonized teeth later. Discovery was published in the journal Nature.

The enamel on our teeth, responsible for the bright smile of the stars, comes from the scales of fish - so says a study published by the British journal Nature.

Enamel is a dental tissue present exclusively in vertebrates. But enamel-like ganoin is present on the scales of countless fossil fish and some primitive fish that still live today.

Illustration of Psarolepis fish, whose fossils were found in southern China; Scientists have found that tooth enamel may have originated from fish scales

To answer this question, researchers from the University of Uppsala, Sweden, and the Beijing Institute of Vertebrate Paleontology and Paleontology (IVPP), evaluated data from two very different fields of research: paleontology and genomics.
Genetic study of Lepisostés (Lepisosteus), one of the rare still living fish with ganoin, revealed the presence of two of the three genes that encode enamel proteins. "This allows us to conclude that ganoin is a type of enamel," he told AFP Per Ahlberg of Uppsala University.

On the other hand, the researchers studied two fossil fish, Psarolepis and Andreolepis, over 400 million years old, and found the presence of enamel on their scales. But not in your teeth.

Result: Originally, enamel was present on the body surface, but not on the teeth.

"Enamel, which for us is synonymous with dental tissue, does not originate in teeth," says Ahlberg. "It evolved over the surface of the vertebrate body, probably from its scales, and colonized the teeth much later."

The study reports that further analysis of primitive fish will be needed to confirm the timing and mechanism that allowed enamel to colonize teeth.

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