Finches on the Galapagos Islands that inspired Charles Darwin to develop the concept of evolution are now helping confirm it — by evolving. A medium sized species of Darwin's finch has evolved a smaller beak to take advantage of different seeds just two decades after the arrival of a larger rival for its original food source. The altered beak size shows that species competing for food can undergo evolutionary change, said Peter Grant of Princeton University, lead author of the report appearing in Friday's issue of the journal Science. Grant has been studying Darwin's finches for decades and previously recorded...