Humans could one day evolve beaks, a biologist has suggested.
Dr Gareth Fraser, from Sheffield University, said the process could see teeth fuse together to form a bill over millions of years.
A beak would be “more robust and practical” than teeth, and less susceptible to wear and tear.
Dr Fraser told the Daily Mail: “It could be possible for humans to evolve to grow beaks, like pufferfish, which may be more robust and practical."
The biologist has also investigated why humans only get two sets of teeth a lifetime, while other animals - like sharks - get lots of new sets.
Having identified the cells responsible for tooth growth in other animals, he believes scientists could eventually stimulate similar cells in humans to create more sets of teeth.
He said: “I guess people will be looking at whether you can make perfect teeth. But there will always be orthodontists employed because even when you have new teeth, there is going to be a need for positioning.
“With our extended lives and modern diets, the limited supply of human teeth is really no longer fit for purpose.
“Our research is focused on looking for ways in which we can replicate the way that fish create an endless supply of teeth and bring this capability to humans.”
But he added that that was unlikely to happen for at least another 50 years.