More and more, scientists are figuring out the molecular changes that have taken place over the course of our evolution. It’s one thing, however, to have a good idea of the ways in which our DNA was altered, but it’s quite another to figure out how those changes affected our ancestors, and how those changes may have spread from an individual to the entire species through a process such as natural selection.

Knowing how genes work makes it possible to come up with hypotheses about how changes to those genes evolved. And today scientists can engineer animals to see if those hypotheses hold up. A couple years ago I blogged about a study on the evolution of our color vision,