Paris: Have you ever wondered why our teeth are so sensitive to pain or even cold drinks? It is perhaps due to the fact that they first evolved for a very different purpose of chewing it for half a mini-mining, suggested a study on Wednesday.
The exact origin of the teeth – and what they were – have long turned out to be elusive to scientists.
Their evolutionary precursors are considered to be hard structures called odontodes which appeared for the first time in the mouth but on the external armor of the first fish around 500 million years ago.
Even today, sharks, rays and catfish are covered with microscopic teeth that make their skin rough like sandpaper.
There are several theories to explain why these odontodes appeared for the first time, including that they protected against predators, helped move through water or stored minerals.
But the new study published in the journal Nature supports the hypothesis that they were originally used as sensory organs which have transmitted sensations to the nerves.
At the beginning, the main author of the study, Yara Haridy, did not even try to track down the origins of the teeth.
Instead, the postdoctoral researcher at the University of Chicago investigated another major question depressing the field of paleontology: what is the oldest fossil of an animal with a spine?
Haridy asked the United States museums to send his hundreds of vertebrate specimens – some so small that they could adapt to the point of a toothpick – so that she can analyze them using a CT scanner.
It started to focus on the dentin, the inner layer of teeth which sends sensory information to the nerves of the pulp.
