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A new report in Nature says that enamel, the substance that coats human teeth, originally began on the scales of ancient fish.
The scientific findings suggest that long ago the material served as a protective defense for the scales of early fish – the ancestors of terrestrial vertebrates, including our own species.
“We hypothesize that enamel originated on the scales, before colonizing the dermal bones and finally the teeth,” the authors write.
The revelations are based on fossil and genetic evidence. Having examined well-preserved fossils of two primitive fish that used to ply the seas more than 400 million years ago — Andreolepis and Psarolepis – the researchers found that both species had enamel layer covering their scales or skull, but neither had it on the teeth.
As for genetic evidence, it was derived from examining the genome of a living fish species — the spotted gar. It has shiny enamel-like substance called ganoine in its scales and on parts of its teeth. The scientists found that proteins in the skin of the spotted gar were identical to proteins linked to formation of enamel in human teeth.
“This is important because it is unexpected,” said the leading researcher, paleontologist Per Erik Ahlberg of Sweden’s University of Uppsala, “In us, enamel is only found on teeth, and it is very important for their function, so it is natural to assume that it evolved there.”
The authors of the research paper suggest there was a point along the evolutionary line when activity of enamel-producing proteins was shifted to different body parts of early fish and from there our teeth were formed.
Agencies/Canadajournal
