Researchers have long wondered where our tooth enamel came from. It’s a uniquely mineralized tissue, unlike anything else on the body of humans and most other animals, and it’s only found on the teeth. However, research now suggests that that’s not where enamel first appeared. It turns out that it first evolved on the skin of ancient fish and was only later associated with the teeth.
Teeth on Their Skin
Although we only have enamel in our mouths, many fish not only have enamel on their teeth, they have it on their skin, too. They have what are known as “dermal denticles,” small tooth-like scales that cover the skin. Today, this is common only in cartilaginous fishes like sharks and rays, but in the past it was common in many species of bony fishes. Today, only primitive bony fish like the Florida gar have these structures.
There used to be dispute about whether this really constituted tooth enamel, and it has a different name, ganoine, but genetic research has confirmed it. The gar genome allows it to produce two of the three enamel matrix proteins that our body uses to produce teeth. And those proteins are produced in the skin, so it’s pretty justifiable to say that ganoine is really a form of enamel.
Which Came First?
But identifying that ganoine is really a form of enamel doesn’t tell us where it originated. For that, researchers looked at primitive fish fossils that were preserved well enough to tell us whether they had enamel, and where that enamel was found. They identified two fossil fish dating from about 400 million years ago, Psarolepis from China and Andreolepis from Sweden.
Andreolepis only had enamel on its scales–there was none in its teeth. Psarolepis had enamel on its scales and on denticles on the face, but it also had none in its teeth. Because these are some of the earliest bony fishes, researchers concluded that it was likely that enamel evolved first on the skin and only later in the mouth.
Wherever enamel came from, we are happy to have it on our teeth. It gives them a unique beauty and toughness. But it’s also vulnerable and needs to be protected with preventive dentistry. If you are looking for an Orlando dentist to help protect the skin of your teeth, please call for an appointment at the office of Dr. Michael L. Weinstock today.