Soon after Charles Darwin published his theory of Natural Selection, he was faced with a puzzle. If natural selection suggests "survival of the fittest," then why do some males have traits that detract from their survival? For instance, the peacock grows a colorful, cumbersome tail that not only attracts predators, but makes it difficult for him to escape those predators. Similarly, the buck grows enormous antlers which are heavy to carry and can easily become tangled in branches, interfering with effective escape from pursuing hunters.