This question has long puzzled thinkers like legendary evolutionary scientist Stephen Jay Gould, who proposed that evolution was "utterly unpredictable and quite unrepeatable." But a new study of Caribbean lizards published today (July 18) in the journal Science suggests that, at least in some circumstances, evolution may be more predictable than previously thought.
It is, as you might imagine, difficult to test what would happen if you could rewind and replay the "tape of life," said Luke Mahler, a study author and researcher at the University of California, Davis. In lieu of time travel, Mahler and his co-authors turned to the Caribbean islands. All of the lizard diversity on four major islands — Cuba, Jamaica, Hispaniola (home to Haiti and the Dominican Republic) and Puerto Rico — arose from a single species as individuals rafted to these spots on logs and other debris over the course of millions of years, Mahler told LiveScience. In other words, it's the perfect natural laboratory to see what might have happened if evolution repeated itself four separate times.