What is it about?
The teeth of mammals are remarkably diverse and precisely suited to their diets. But how did these complex tooth shapes come to be? To understand this, we studied how the shape of vole molars changed during evolution and throughout embryonic development, and found that a slight shift in their mode of growth has influenced their evolution over the last six million years. As vole embryos develop, their molars become long and narrow—and that extra length allows more small bumps called cusps to form on the tooth surface. More cusps make the tooth more complex, which helps to grind tough foods—particularly the grasses that voles feed on—more effectively. We found that faster tooth growth in voles compared to mice leads to longer and narrower molars with more cusps. The same pattern appeared in fossil voles and lemmings, which repeatedly evolved more complex molars as they became more elongated and narrower. Therefore, changes in the way molars develop shaped the evolution of vole molar morphology.
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Why is it important?
Our study confirms that tooth development played a key role in the evolution of mammalian teeth and shows that large-scale evolutionary changes can be explained by small changes in the way organs grow. This means that large evolutionary changes in morphology may not require equally large genetic changes. Instead, minor tweaks in the existing mechanisms that control an organ’s development can create new pathways for the evolution of more complex forms. However, we also found that the most complex tooth shapes evolve and develop more slowly, suggesting that the same developmental mechanisms that enable new evolutionary paths may also limit potential changes.
Perspectives
What makes this study so exciting to me is how we got to integrate different fields of biology to answer our research question. There is something fascinating in finding out that a few days of lab observations can help explain millions of years of evolution. Results like these showcase the potential of combining data from fossils and living animals to connect different scales at which evolution occurs. These kinds of integrative approaches are essential if we want to truly understand how evolution works, because they can reveal that findings from various branches of evolutionary theory may be more closely connected than we thought. I hope this inspires more researchers to seek out these connections and engage with scientists outside their own field to answer questions together.
Fabien Lafuma
Helsingin Yliopisto
Read the Original
This page is a summary of: Six million years of vole dental evolution shaped by tooth development, Proceedings of the National Academy of Sciences, July 2025, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2505624122.
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