equently
occur, the most useful of their animals would be preserved: the value
set upon animals by savages is shown by the inhabitants of Tierra del
Fuego devouring their old women before their dogs, which as they
asserted are useful in otter-hunting{201}: who can doubt but that in
every case of famine and war, the best otter-hunters would be preserved,
and therefore in fact selected for breeding. As the offspring so
obviously take after their parents, and as we have seen that savages
take pains in crossing their dogs and horses with wild stocks, we may
even conclude as probable that they would sometimes pair the most useful
of their animals and keep their offspring separate. As different races
of men require and admire different qualities in their domesticated
animals, each would thus slowly, though unconsciously, be selecting a
different breed. As Pallas has remarked, who can doubt but that the
ancient Russian would esteem and endeavour to preserve those sheep in
his flocks which had the thickest coats. This kind of insensible
selection by which new breeds are not selected and kept separate, but a
peculiar character is slowly given to the whole mass of the breed, by
often saving the life of animals with certain characteristics, we may
feel nearly sure, from what we see has been done by the more direct
method of separate selection within the last 50 years in England, would
in the course of some thousand years produce a marked effect.

{200} See _Origin_, Ed. i. p. 33, vi. p. 38. The evidence is given
in the present Essay rather more fully than in the _Origin_.

{201} _Journal of Researches_, Ed. 1860, p. 214. "Doggies catch
otters, old women no."

_Crossing Breeds._

When once two or more races are formed, or if more than one race, or
species fertile _inter se_, originally existed in a wild state, their
crossing becomes a most copious source of new races{202}. When two
well-marked races are crossed the offspring in the first generation take
more or less after either parent or are quite intermediate between them,
or rarely assume characters in some degree new. In the second and
several succeeding generations, the offspring are generally found to
vary exceedingly, one compared with another, and many revert nearly to
their ancestral forms. This greater variability in succeeding
generations seems analogous to the breaking or variability of organic
beings after having been bred for some generations