The theory of evolution has long been an interesting subject for scientists around the world, ever since Darwin’s proposal. Many new findings have shaped our understanding of evolution and some have changed what we knew thus far. Now a new study by scientists on fruitflies might further change how we have understood the importance of ‘trade-offs’ in evolution. The study has discovered that fruitflies develop immunity to a type of bacteria over a few generations without losing any other desirable trait, prompting scientists to believe that they have obtained immunity for free, a concept that was always associated with trade-offs.