Science

selection, in which mutations give rise to adaptations that are passed on to offspring and alter their chances of survival. Scientists have assumed that these mutations were random and that the first step in evolution by natural selection was, therefore, also random. But this may not be entirely true, the new study suggests.

"The idea of random mutation has been around for over a hundred years in biology and is something you hear so often as a student that it is easy to take it for granted," Monroe said. "Even as a practicing geneticist and evolutionary biologist, I had never seriously questioned the idea."

The new finding does not disprove or discredit the theory of evolution, and the researchers said randomness still plays a big role in mutations. But the study does show that these genetic alterations are more complex than scientists previously believed.