As a consequence of continued variability, and more especially of reversion,
all highly improved races, if neglected or not subjected to incessant
selection, soon degenerate. Youatt gives a curious instance of this in some
cattle formerly kept in Glamorganshire; but in this case the cattle were not
fed with sufficient care. Mr. Baker, in his memoir on the Horse, sums up: "It
must have been observed in the preceding pages that, whenever there has been
neglect, the breed has proportionally deteriorated." (21/57. 'The Veterinary'
volume 13 page 720. For the Glamorganshire cattle see Youatt on 'Cattle' page
51.) If a considerable number of improved cattle, sheep, or other animals of
the same race, were allowed to breed freely together, with no selection, but
with no change in their condition of life, there can be no doubt that after a
score or hundred generations they would be very far from excellent of their
kind; but, from what we see of the many common races of dogs, cattle, fowls,
pigeons, etc., which without any particular care have long retained nearly the
same character, we have no grounds for believing that they would altogether
depart from their type.
It is a general belief amongst breeders that characters of all kinds become
fixed by long-continued inheritance. But I have attempted to show in the
fourteenth chapter that this belief apparently resolves itself into the
following proposition, namely, that all characters whatever, whether recently
acquired or ancient, tend to be transmitted, but that those which have already
long withstood all counteracting influences, will, as a general rule, continue
to withstand them, and consequently be faithfully transmitted.
TENDENCY IN MAN TO CARRY THE PRACTICE OF SELECTION TO AN EXTREME POINT.
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