Page - 507 - in The Origin of Species
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Text of the Page - 507 -
RECAPITULATION AND CONCLUSION 507
Variability is not actually caused by man ; he only uninten-
tionally exposes organic beings to new conditions of life, and
then nature acts on the organisation and causes it to vary.
But man can and does select the variations given to him by
nature, and thus accumulates them in any desired manner.
He thus adapts animals and plants for his own benefit or
pleasure. He may do this methodically, or he may do it
unconsciously by preserving the individuals most useful or
pleasing to him without any intention of altering the breed.
It is certain that he can largely influence the character of a
breed by selecting, in each successive generation, individual
differences so slight as to be inappreciable except by an edu-
cated eye. This unconscious process of selection has been
the great agency in the formation of the most distinct and
useful domestic breeds. That many breeds produced by man
have to a large extent the character of natural species, is
shown by the inextricable doubts whether many of them are
varieties or aboriginally distinct species.
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 from the high geo-
metrical 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 sur-
vive. A grain in the balance may determine which indi-
viduals shall live and which shall die,—which variety or
species shall increase in number, and which shall decrease,
or finally become extinct. As the individuals of the same
species come in all respects into the closest competition with
each other, the struggle will generally be most severe between
them; it will be almost equally severe between the varieties
of the same species, and next in severity between the species
of the same genus. On the other hand the struggle will often
be severe between beings remote in the scale of nature. The
slightest advantage in certain individuals, at any age or dur-
back to the
book The Origin of Species"
The Origin of Species
- Title
- The Origin of Species
- Author
- Charles Darwin
- Publisher
- P. F. Collier & Son
- Location
- New York
- Date
- 1909
- Language
- English
- License
- PD
- Size
- 10.5 x 16.4 cm
- Pages
- 568
- Keywords
- Evolutionstheorie, Evolution, Theory of Evolution, Naturwissenschaft, Natural Sciences
- Categories
- International
- Naturwissenschaften Biologie
Table of contents
- EDITOR'S INTRODUCTION 5
- AN HISTORICAL SKETCH of the Progress of Opinion on the Origin of Species 9
- INTRODUCTION 21
- Variation under Domestication 25
- Variation under Nature 58
- Struggle for Existence 76
- Natural Selection; or the Survival of the Fittest 93
- Laws of Variation 145
- Difficulties of the Theory 178
- Miscellaneous Objections to the Theory of Natural Selection 219
- Instinct 262
- Hybridism 298
- On the Imperfection of the Geological Record 333
- On the Geological Succession of Organic Beinss 364
- Geographical Distribution 395
- Geographical Distribution - continued 427
- Mutual Affinities of Organic Beings: Morphology: Embryology: Rudimentary Organs 450
- Recapitulation and Conclusion 499
- GLOSSARY 531
- INDEX 541