Darwin’s Greatest Discovery: Design without Designer. Francisco J. Ayala University of California, Irvine. William Paley Natural Theology , 1802.
Darwin’s Greatest Discovery:Design without Designer Francisco J. Ayala University of California, Irvine
Alfred Russel Wallace, “On the Tendency of Varieties to Depart Indefinitely from the Original Type; Instability of Varieties Supposed to Prove the Permanent Distinctness of Species” Journal of the Proceedings of the Linnaean Society of London (Zoology) 3 (1858): 53-62.
We believe that there is a tendency in nature to the continued progression of certain classes of varieties further and further from the original type—a progression to which there appears no reason to assign any definite limits. This progression, by minute steps, in various directions, but always checked and balanced by the necessary conditions, subject to which alone existence can be preserved, may be followed out so as to agree with all the phenomena presented by organized beings, their extinction and succession in past ages, and all the extraordinary modifications of form, instinct and habits which they exhibit.
Charles DarwinThe Origin of Species As more individuals are produced than can possibly survive … Can it be thought improbable, seeing that variations useful to man have undoubtedly occurred, that other variations useful in some way to each being in the great and complex battle of life, should sometimes occur in the course of thousands of generations? If such do occur, can we doubt that individuals having any advantage, however slight, over others, would have the best chance of surviving and of procreating their kind? On the other hand, we may feel sure that any variation in the least degree injurious would be rigidly destroyed. This preservation of favorable variations and the rejection of injurious variations, I call Natural Selection.
Stages of eye complexity in mollusks (limpet Patella)