Paris: Have you ever wondered why our teeth are so sensitive to pain or even just cold drinks? This may be because they first developed for a much different purpose than chewing half a billion years ago, a study suggested on Wednesday.

The exact origin of teeth – and what they were for – has long proved to be evasive for scientists.

Their evolutionary precursors are believed to be harsh structures called Odontodes, which at first did not appear in the mouth, but on the external armor of the earliest fish about 500 million years ago.

Even today, sharks, stingrays and catfish are covered with microscopic teeth that make their skin rough as sandpaper.

There are several theories as to why these odontodes first emerged, including that they protected themselves from predators, helped with movement through the water or stored minerals.

But the new study published in the journal Nature supports the hypothesis that they were originally used as sensory organs that transferred sensations to nerves.

First, the study’s lead author Yara Haridy did not even try to chase the origin of the teeth.

Instead, the post -doctoral researcher at the University of Chicago examined another major question that amazed the area of ​​Palaeontology: What is the oldest fossil of an animal with a backbone?

Haridy asked museums across the United States to send her hundreds of vertebrate copies – some so small that they could take care of the tip of a toothpick – so she could analyze them using a CT scanner.

She began to focus on dentin, the inner layer of teeth that sends sensory information to nerves in the mass.