Free Shadows of Forgotten Ancestors by Carl Sagan, Ann Druyan Page B

up in certain directions useful to him. In this sense he may be said to have made for himself useful breeds.
    … [H]ardly any one is so careless as to breed from his worst animals …
    If there exist savages so barbarous as never to think of the inherited character of the offspring of their domestic animals, yet any one animal particularly useful to them, for any special purpose, would be carefully preserved during famines and other accidents, to which savages are so liable, and such choice animals would thus generally leave more offspring than the inferior ones; so that in this case there would be a kind of unconscious selection going on …
    Man … can never act by selection, excepting on variations which are first given to him in some slight degree by nature …
    This preservation [in Nature] of favourable individual differences and variations, and the destruction of those which are injurious, I have called Natural Selection, or the Survival of the Fittest Variations neither useful nor injurious would not be affected by natural selection …
    When we see leaf-eating insects green, and bark-feeders mottled-grey; the alpine ptarmigan white in winter, the red-grouse the colour of heather, we must believe that these tints are of service to these birds and insects in preserving them from danger …
    If it profit a plant to have its seeds more and more widely disseminated by the wind, I can see no greater difficulty in this being effected through natural selection, than in the cotton-planter increasing and improving by selection the down in the pods on his cotton-trees …
    There is no reason why the principles which have acted so efficiently under domestication should not have acted under nature. In the survival of favoured individuals and races, during the constantly-recurrent Struggle for Existence, we see a powerful and ever-acting form of Selection. The struggle for existence inevitably follows fromthe high geometrical ratio of increase which is common to all organic beings. This high rate of increase is proved by calculation,—by the rapid increase of many animals and plants during a succession of peculiar seasons, and when naturalised in new countries. More individuals are born than can possibly survive. A grain in the balance may determine which individuals shall live and which shall die,—which variety or species shall increase in number, and which shall decrease, or finally become extinct … The slightest advantage in certain individuals, at any age or during any season, over those with which they come into competition, or better adaptation in however slight a degree to the surrounding physical conditions, will, in the long run, turn the balance. 4
     
    In his 1858 paper in the Linnaean Society
Proceedings
, he asks us to imagine a being who could continue selecting, with unfailing attention, for a single desired characteristic over “millions of generations.” Natural selection implies—in effect, although not literally—that such a being exists. “We have almost unlimited time” for evolution, he wrote.
    Darwin then went on to propose that, over such immense periods of time, continuing natural selection may generate such a divergence of an organism from its parental stock as to constitute a new species. Giraffes develop long necks because those whose necks are—by some spontaneous genetic variation—a little longer are able to browse on the topmost foliage, flourish when others are ill-fed, and leave more offspring than their shorter-necked fellows. He pictured a vast family tree, symbolic of the varied forms of life, slowly growing, branching, and anastomosing, organisms evolving to produce all the “exquisite adaptations” of the natural world.
    There is “grandeur,” he thought, in the fact that “from so simple a beginning, endless forms most beautiful and most wonderful have been, and are being evolved.”
    Analogy would lead me one step farther, namely, to the belief that all animals