From toothed dinosaurs to toothless birds: evolutionary clues from people with missing teeth.

What is it about?

Birds are living dinosaurs, and their ancient ancestors had teeth. Our research suggests that clues to how birds lost their teeth during evolution may be found in people whose teeth never form. The connection involves an ancient system of messages that guides tooth development. A gene called C2CD3 helps cells build tiny antennas called cilia. These antennas help cells receive messages that guide where teeth form, when they develop and what shape they take. Changes in this system can alter the body’s ability to make teeth. We studied 24 people from 16 families who carried changes in C2CD3. Some had missing teeth, while others had extra teeth, unusually small teeth or natal teeth—teeth present at birth. These differences offered a window into the ancient machinery that builds teeth. In mice, disrupting this gene produced missing, smaller or extra teeth. In developing chickens carrying a change in the same gene, we found tiny structures resembling the earliest beginnings of teeth. The chickens did not grow complete teeth, but these structures suggest that birds still retain parts of their ancestors’ tooth-making instructions. Our findings suggest that changes in the same ancient messaging system may help explain both tooth loss during bird evolution and why some people never develop certain teeth today. Changes in how these messages work may have helped silence tooth development as birds evolved. Families with dental differences are helping us uncover a story millions of years in the making: how evolution changes the ability to form teeth. Our hope is that understanding these ancient instructions will one day help scientists find ways to grow replacement teeth—turning discoveries about life’s past into new possibilities for future smiles.

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Photo by Hussain Badshah on Unsplash

Photo by Hussain Badshah on Unsplash

Why is it important?

Significance of this study This study matters because it connects an evolutionary mystery—how birds lost their teeth—with a question families face today: why some people never develop certain teeth. Our findings suggest that both may involve changes in the same ancient system of cell messages that guides tooth formation. By studying people, mice and chickens, we reveal the importance of C2CD3 and tiny cell “antennas” in tooth development. Early tooth-like structures in chicken embryos suggest that birds still retain some ancestral tooth-making instructions. This offers clues to how changes in the use of these instructions may have helped switch off tooth development during evolution. These findings help us understand why teeth develop differently and may guide future research into growing replacement teeth. Families today are helping us uncover our evolutionary past—and opening possibilities for the future of dental care.

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