Evolution is actually a Sadie Hawkins dance, as new research shows females not only determine whether male animals develop bright colors, but also how fast new species develop. 

Research led by David Reznick, a UC Riverside biology professor, used fish often seen in pet stores, like guppies and swordtails, to test a hypothesis proposed by David and Jean Zeh at the University of Nevada, Reno. They predicted that the way mothers nurture their young influences the evolution of male traits, and Reznick’s team is the first to find that the prediction was correct. 

A paper describing the research was published online today in Nature Communications.