Man does Man does 1859 1860 1861 1866 1869 | Variability is 1872 |
not actually
produce variability; produce variability; 1859 1860 1861 1866 1869 |
caused by man; 1872 |
he only unintentionally exposes organic beings to new conditions of life, and then nature acts on the
organisation, organisation, 1859 1860 1861 1866 1869 | organisation 1872 |
and causes
variability. variability. 1859 1860 1861 1866 1869 |
it to vary. 1872 |
But man can and does select the variations given to him by nature, and thus
accumulate accumulate 1859 1860 1861 1866 1869 | accumulates 1872 |
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
to him at the time, to him at the time, 1859 1860 |
to him at the time 1861 |
to him 1866 |
or pleasing to him 1869 1872 |
without any
thought thought 1859 1860 1861 1866 | intention 1869 1872 |
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
quite quite 1859 1860 | quite 1861 1866 1869 1872 |
inappreciable
by an by an 1859 1860 1861 1866 | except 1869 1872 |
uneducated uneducated 1859 1860 1861 1866 |
by an educated 1869 1872 |
eye. This
process process 1859 1860 1861 1866 1869 | unconscious process 1872 |
of selection has been the great agency in the
production production 1859 1860 1861 1866 | formation 1869 1872 |
of the most distinct and useful domestic breeds. That many
of the of the 1859 1860 1861 1866 | of the 1869 1872 |
breeds produced by man have to a large extent the character of natural species, is shown by the inextricable doubts whether
very very 1859 1860 1861 1866 | very 1869 1872 |
many of them are varieties or
aboriginal aboriginal 1859 1860 | aboriginally 1861 1866 1869 1872 |
species. species. 1859 1860 | distinct species. 1861 1866 1869 1872 |
|
|
There is no
obvious obvious 1859 1860 1861 1866 1869 | obvious 1872 |
reason why the principles which have acted so efficiently under domestication should not
have acted have acted 1859 1860 1861 1866 1872 | act 1869 |
under nature. In the
preservation preservation 1859 1860 1861 1866 | survival 1869 1872 |
of favoured individuals and races, during the constantly-recurrent Struggle for Existence, we see
the most the most 1859 1860 1861 1866 | a 1869 1872 |
powerful and ever-acting
means means 1859 1860 1861 1866 | form 1869 1872 |
of
selection. selection. 1859 1860 1861 1866 | Selection. 1869 1872 |
The struggle for existence inevitably follows from the high geometrical ratio of increase which is common to all organic beings. This high rate of increase is proved by
calculation,— calculation,— 1860 1861 1866 1869 1872 | calculation, 1859 |
by the
rapid increase of many animals and plants during rapid increase of many animals and plants during 1860 1861 1866 1869 1872 |
effects of 1859 |
a succession of peculiar seasons,
or when naturalised in a new country. or when naturalised in a new country. 1860 1861 1866 |
and by the results of naturalisation, as explained in the third chapter. 1859 |
and when naturalised in a new country. 1869 |
and when naturalised in new countries. 1872 |
More individuals are born than can possibly survive. A grain in the balance
will will 1859 1860 1861 1866 | may 1869 1872 |
determine which
individual individual 1859 1860 1861 1866 | individuals 1869 1872 |
shall live and which shall die,— which variety or species shall increase in number, and which
|