Dragon fly & its wings

As early as the 1920s, scientists began to realize that mutations had huge ramification for evolution. These researchers -- foremost among them the British mathematician Ronal Fisher en.wikipedia.org/wiki/Ronald_Fisher and the American biologist Sewall Wright -- synthesized natural selection and genetics, putting Darwin’s theory on a far more solid foundation ` Page 78

Fisher en.wikipedia.org/wiki/Ronald_Fisher made a particularly important breakthrough which he demonstrated that natural selection progresses by the accumulation of many small mutations rather than by a few giant ones. Fisher used some esoteric math to prove this point, but a simple hypothetical example can made it clear. Consider a dragonfly’s wings. If a dragonfly has particular short wings, it may not be able to generate enough lift to stay off the ground but if it has wings that are too long, they may be too heavy to flap. Somewhere between short wings and long ones is the length that brings the greatest fitness. If you chart out his relationship between length and fitness on a graph, you draw a hill, with its peak at the optimal length of the wings. If you were actually measure the wings of dragonflies and plot them on this graph, they might cluster as points near the hills peak.

Now imagine that a mutation cropped up that changed the length of the dragonfly’s wings. If the insect fitness gets lowered as a result, insects with a better wing design may outcompete its offspring. But if the mutation pushes the dragonfly closer to the peak of fitness, natural selection will favor it. In other words, natural selection tends to push life up th hillside of fitness. ~ Page 79