In Lewis Carroll's "Through the Looking-Glass," the Red Queen explains to Alice how a race works in Wonderland, stating, "Now, here, you see, it takes all the running you can do, to keep in the same place." So, too, does this statement hold true in nature. Competitive species are under constant pressure to evolve as rapidly as possible so as to outgun their competition, and this is often referred to as the Red Queen Theory. The rabbit needs to outrun the fox to avoid being killed, whereas the fox needs to catch the rabbit in order to avoid starvation.