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FIGURE 1.1 Steps in the evolution of eye complexity in living mollusks. The simplest eye is found in limpets, consisting of only a few pigmented cells, slightly modified from typical epithelial (skin) cells. Slit-shell molluskshave a slightly more advanced organ, consisting of some pigmented cells shaped as a cup. The octopus eye is quite complex, with components similar to those of the human eye such as cornea, iris, refractive lens, and retina. (Adapted from “Evolution, The Theory of.” By courtesy of Encyclopaedia Britannica, Inc.)


Natural selection sorting out spontaneously arising mutations is a creative process because it causes favorable mutations to combine and accumulate, yielding a great diversity of organisms over eons of time. But there are important features that distinguish the kind of “design” achieved by natural selection, namely the adaptations of organisms, from the kind of design produced by an intelligent designer, an engineer.

An engineer has a preconception of what the design is supposed to achieve and will select suitable materials and arrange them in a preconceived manner so that it fulfills the intended function. On the contrary, natural selection does not operate according to some preordained plan. It is a purely natural process resulting from the interacting properties of physicochemical and biological entities. Natural selection is simply a consequence of the differential survival and reproduction of living beings. It has some appearance of purposefulness because it is conditioned by the environment: which organisms survive and reproduce more effectively depends on which variations they happen to possess that are useful or beneficial to them in the place and at the time where they live.

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