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|OriginOfSpecies - 475 Rows|
|06 - Difficutiles in Theory||06-12 - Organs not in all Cases Absolutely Perfect||120||
Natural selection tends only to make each organic being as perfect as, or slightly more perfect than, the other inhabitants of the same country with which it comes into competition.
And we see that this is the standard of perfection attained under nature.
The endemic productions of New Zealand, for instance, are perfect one compared with another; but they are now rapidly yielding before the advancing legions of plants and animals introduced from Europe.
Natural selection will not produce absolute perfection, nor do we always meet, as far as we can judge, with this high standard under nature.
The correction for the aberration of light is said by Muller not to be perfect even in that most perfect organ, the human eye.
Helmholtz, whose judgment no one will dispute, after describing in the strongest terms the wonderful powers of the human eye, adds these remarkable words: "That which we have discovered in the way of inexactness and imperfection in the optical machine and in the image on the retina, is as nothing in comparison with the incongruities which we have just come across in the domain of the sensations.
One might say that nature has taken delight in accumulating contradictions in order to remove all foundation from the theory of a pre-existing harmony between the external and internal worlds."
If our reason leads us to admire with enthusiasm a multitude of inimitable contrivances in nature, this same reason tells us, though we may easily err on both sides, that some other contrivances are less perfect.
Can we consider the sting of the bee as perfect, which, when used against many kinds of enemies, cannot be withdrawn, owing to the backward serratures, and thus inevitably causes the death of the insect by tearing out its viscera?
|06 - Difficutiles in Theory||06-12 - Organs not in all Cases Absolutely Perfect||100||
Natural selection cannot possibly produce any modification in a species exclusively for the good of another species; though throughout nature one species incessantly takes advantage of, and profits by, the structures of others.
But natural selection can and does often produce structures for the direct injury of other animals, as we see in the fang of the adder, and in the ovipositor of the ichneumon, by which its eggs are deposited in the living bodies of other insects.
If it could be proved that any part of the structure of any one species had been formed for the exclusive good of another species, it would annihilate my theory, for such could not have been produced through natural selection.
Although many statements may be found in works on natural history to this effect, I cannot find even one which seems to me of any weight.
It is admitted that the rattlesnake has a poison-fang for its own defence, and for the destruction of its prey; but some authors suppose that at the same time it is furnished with a rattle for its own injury, namely, to warn its prey.
I would almost as soon believe that the cat curls the end of its tail when preparing to spring, in order to warn the doomed mouse.
|06 - Difficutiles in Theory||06-13 - Summary: The Law of Unity of Type and of the Conditions of Existence Embraced by the Theory of Natural Selection||60||
Natural selection can produce nothing in one species for the exclusive good or injury of another; though it may well produce parts, organs, and excretions highly useful or even indispensable, or again highly injurious to another species, but in all cases at the same time useful to the possessor.
In each well-stocked country natural selection acts through the competition of the inhabitants, and consequently leads to success in the battle for life, only in accordance with the standard of that particular country.
Hence the inhabitants of one country, generally the smaller one, often yield to the inhabitants of another and generally the larger country.
For in the larger country there will have existed more individuals and more diversified forms, and the competition will have been severer, and thus the standard of perfection will have been rendered higher.
Natural selection will not necessarily lead to absolute perfection; nor, as far as we can judge by our limited faculties, can absolute perfection be everywhere predicated.
|04 - Natural Selection||04-12 - On the Degree to which Organisation tends to advance||10||
Natural Selection acts exclusively by the preservation and accumulation of variations, which are beneficial under the organic and inorganic conditions to which each creature is exposed at all periods of life.
The ultimate result is that each creature tends to become more and more improved in relation to its conditions.
This improvement inevitable leads to the gradual advancement of the organisation of the greater number of living beings throughout the world.
But here we enter on a very intricate subject, for naturalists have not defined to each other's satisfaction what is meant by an advance in organisation.