Vole teeth reveal how a simple change can create complex new features over time

At a time when biodiversity is under severe pressure from human activities, understanding how evolution works is more important than ever. A new study about vole teeth, published in PNASreveals that evolution doesn’t always require complicated genetic changes to create complex new features.

“When we tried to understand the origin of the voles’ strange molars, we found that a simple change in tooth growth acting over millions of years was responsible for the success of these small rodents. Over the past six million years, their molars gained more and more cusps—the pointed tips that help grind food—eventually resembling the grinding teeth of much larger herbivores like horses or elephants,” said lead author Fabien Lafuma, a doctoral researcher at the University of Helsinki.

These adaptations made voles excellent grass-eaters, which allowed them to thrive during the ice ages. But what’s striking is that the evolution of vole teeth reflects the way they develop in the womb.

A surprisingly simple change in tooth growth gave voles a head start compared to other rodents: speeding up the formation of cusps, so more of them can develop as the tooth grows longer.

“By showing how development steers the way species adapt, studying teeth can help us understand how life responds to changing environments. Such knowledge is essential to guide conservation efforts as species today face unprecedented climate breakdown and habitat loss,” Lafuma explains.