nd becoming thus
instinctive, or habitual, in remote descendants.

But on Mr. Darwin's own ground, it maybe objected that this notion fails to
account for "abhorrence," and "moral reprobation;" for, as no stream can
rise higher than its source, the original "slight feeling" which was
_useful_ would have been perpetuated, but would never have been augmented
beyond the degree requisite to ensure this beneficial preference, and
therefore would not certainly have become magnified into "abhorrence." It
will not do to assume that the union of males and females, each possessing
the required "slight feeling," must give rise to offspring with an
intensified feeling of the same kind; for, apart from reversion, Mr. Darwin
has called attention to the unexpected modifications which sometimes result
from the union of _similarly_ constituted parents. Thus, for example, he
tells us:[204] "If two top-knotted canaries are matched, the young, instead
of having very fine top-knots, are generally bald." From examples of this
kind, it is fair, on Darwinian principles, to infer that the union of {191}
parents who possessed a similar inherited aversion might result in
phenomena quite other than the augmentation of such aversion, even if the
two aversions should be altogether similar; while, very probably, they
might be so different in their nature as to tend to neutralize each other.
Besides, the union of parents so similarly emotional would be rare indeed
amongst savages, where marriages would be owing to almost anything rather
than to congeniality of mind between the spouses. Mr. Wallace tells
us,[205] that they choose their wives for "rude health and physical
beauty," and this is just what might be naturally supposed. Again, we must
bear in mind the necessity there is that _many individuals_ should be
similarly and simultaneously affected with this aversion from
consanguineous unions; as we have seen in the second chapter, how
infallibly variations presented by only a few individuals, tend to be
eliminated by mere force of numbers. Mr. Darwin indeed would throw back
this aversion, if possible, to a pre-human period; since he speculates as
to whether the gorillas or orang-utans, in effecting their matrimonial
relations, show any tendency to respect the prohibited degrees of
affinity.[206] No tittle of evidence, however, has yet been adduced
pointing in any such direction, though surely if it were of such importance
and efficiency as to result