Evolution Within Limits: Nature Study Identifies Genetic Basis for Galápagos Finch Beak Variation

Decades ago researchers Peter and Rosemarie Grant conducted painstaking research on finches in the Galápagos Islands. They found that during a drought period the seeds eaten by the finches became tougher, and those birds with bigger beaks were better able to survive and reproduce. After the drought ended, however, the seeds returned to their normal state and beaks also returned to their pre-drought sizes. As the Grants explained:

Effects of the droughts of 1977 and 1982 were approximately off...