Chapter 7: Objections to Natural Selection

In this comprehensive examination of evolutionary theory, the focus is on addressing diverse scientific criticisms regarding the mechanism of natural selection. A central theme is the rebuttal of the argument that natural selection is incompetent to explain the early, incipient stages of complex and useful structures. Through a series of detailed biological case studies, it is argued that highly specialized organs—such as the giraffe's elongated neck for high-altitude browsing, the intricate baleen plates of whales used for sifting water, and the asymmetrical eyes of flat-fish—did not appear through sudden, massive modifications but rather through a sequence of finely graduated, beneficial steps. The text illustrates how these transitions occur by looking at intermediate forms, such as the varying beak structures in the duck family or the protective mimicry of insects that begins with a rude, accidental resemblance to their environment. Furthermore, the discussion introduces the "laws of growth" and "correlated variation" to explain why certain morphological traits might appear useless; these features often change as a secondary result of modifications in other vital parts or possess functions, like the tactile nerves in a mouse’s ear, that are not immediately obvious. The development of mammary glands is hypothesized to have started as simple cutaneous secretions within a marsupial-like pouch, gradually perfected through selection for more nutritious fluids. By challenging the necessity of an "internal force" for progressive development, the chapter emphasizes that evolution is a slow, cumulative process. This gradualist view is further supported by embryology, which reveals that even the most specialized limbs and wings begin as indistinguishable structures in the embryo, suggesting that significant changes are the result of small, inherited variations occurring after early youth rather than miraculous, abrupt transformations.