A study published by Journal of Vertebrate Paleontology claims that the very first tooth most likely belong to an ancient fish. Thevery first pearly whites might have been a set of very sharp scales on a fish's face.

The study supports the "outside-in" hypothesis of tooth evolution, which hypothesizes that the first teeth came from scales instead of coming out from the pharynx to the mouth. The researchers studied the ancient fish ischnacanthid acanthodians that lived during the early Devonian period from 416 to 397 million years ago. Other fish species analyzed in the study were excavated from Man on the Hill site in the Mackenzie Mountains of Canada.

"Our findings support the idea that teeth evolved from modified pointed scales on the mouth margins (lips) as we see in Obtusacanthus,"" said the project leader of the research, Stephen Blais from University of Alberta in an interview with Discovery News.

The study claims that teeth were evolved to gain a major advantage over other species which by that time were just passive eaters. This has first differentiated the hunter and the prey from each other. Gaining teeth would enable organisms with them to hunt down food instead of just filter-feeding any organisms that pass through their mouth. Being the first predator would have given the specie the advantage in natural selection as they would be the ones who would be on top of the food chain while everyone else are prey. The teeth gave them the ability to grasp prey and hold on until they manage to swallow it.

The research also hypothesizes that the jaws must have evolved earlier than teeth. The first smile might be a toothless smile instead of a disturbing prickly smile.

Co-author of the study Lindsay MacKenzie of the University of Montana's Geosciences Department claims that since teeth have evolved from scales, it first came in sets instead of coming out one by one to mirror scale groupings.

"Interactions between predators and prey through time only increased their (teeth's) importance, leading to highly specialized teeth, such as those in mammals," Blais stated on predator-prey relationship.

The teeth might be the first step in the evolutionary weapons race. Now all animals including man have teeth and each with their own specializations from herbivores to carnivores during the millions of years of inter-species battle.