Find out how did a tooth enamel evolve

Scientists said that they have figured out that the enamel that covers our teeth was originated in the scales of ancient fish. A new study in the Journal of Nature claims humans, like fish, couldn’t have survived if it hadn’t been for the protective shield of their skin.

Enamel, shiny and white, is one of the main tissues in teeth in most vertebrates, composed nearly entirely of calcium phosphate. Neither fish had enamel on its teeth.

Enamel is the strongest tissue produced by the human body, as well as by many other species of vertebrates from our planet.

Prof. Per Ahlberg of Uppsala University, senior author on the study, explained: “Psarolepis romeri and Andreolepis are among the earliest bony fishes, so we believe that their lack of tooth enamel is primitive and not a specialization”. These hard tissues consist of the same genes that are clustered together in a genome.

The researchers studied the fossil of a fish called Andreolepis, which lived 425 million years ago in Sweden, and found it had a thin layer of enamel on its scales. Researchers have reached this conclusion after comparing the skeletons of dead fish dating back to hundreds of million years and the DNA samples of alive species. Tooth enamel is the hardest tissue in the body and is present nowhere else so why do we have it and where does it come from?

The bony fish from the Silurian Period, when marine life were making a number of evolutionary advances, had enamel coatings on their scales but nothing on their teeth.

This revealed that a single species can have enamel on parts of its body but not on others.

Some scientists had suggested the hardened scales gradually migrated into the mouth over eons of evolution, but the new study suggests it may have been the pattern of enamel production that moved, rather than a movement of already enameled structures.

But where did enamel originate – in the mouth, in the skin, or both at once?

Andreolepis, which lived across the identical time as Psarolepis, has been a puzzle to scientists. Uppsala University in Sweden and the Institute of Vertebrate Palaeontology and Palaeoanthropology (IVPP) in Beijing, China conducted the interesting research project and found that “dermal denticles” – little tooth-like scales had a material similar to tooth enamel. Psarolepis also had enamel on denticles covering its faces.

The fish intrigued researchers because it is considered one of the world’s oldest that was known to have enamel.