Darwin noticed differences in the beak shapes of finches on the various islands of the Galapagos and surmised that they all might have evolved from a common ancestor on the mainland. If Darwin had known about molecular biology, a field of study that did not exist at the time he lived, how might he have used it to test his hypothesis? He could have done DNA tests on the birds to see how closely they were related. He could have checked to see if they shared similar cellular structures indicating their common ancestry. He could have used modern tools to make more accurate measurements of beak shape and size. He could have genetically engineered finches with extreme beak shapes to see how they survived.