The Relations of Moral Philosophy to Speculation Concerning the Origin of Man [pp. 288-302]

MORAL PHILOSOPHY AND THE ORIGIN OF MAN. 291
hereafter will show how far we are from being in possession of
rational warrant for such expectation.
Equally insufficient for the contemplated purpose are discussions concerning the relative intelligence of the higher animals.
This is a region of inquiry which cannot be overlooked, yet cannot be conclusive. That some classes of animals show great intelligence, and that some tribes of men are low in the scale of
intelligence, are undoubted facts, and facts of real consequence
in the discussion; but they have much less bearing on the question as to the origin of man than seems commonly supposed.
In order to show this, it is not needful to insist on the vast
chasm between the least intelligent tribes of men and the most
intelligent races of animals. It is even more important to observe that we are without any theory of animal intelligence, notwithstanding the wonderful advances of physiological science.
Within the area of Physiology we are still wandering deviously
in a most perplexing thicket. We find high intelligence in
some animals which do not stand high in the scale of organic
being; on the other hand, we find the largest and most important nerve-cells in the brain of animals which do not show much
intelligence; and, as a natural consequence, science has no
theory to offer of the facts of intelligence included within the
sphere of comparative physiology.
This being the position of matters for the present, even when
we place ourselves implicitly under the guidance of Physiology,
it is only what should be expected, if we find in society a strong
antipathy to the speculation which asks us to accept the hypothesis that the human race has risen to its present exalted position by a series of slow advances from the low levels of the
water-lily or the shell-fish. There is not in the public mind obstinate reluctance to surrender opinions long cherished. There
is even a singular willingness to forsake long-accepted theories
for the purpose of adopting new, tho unverified suggestions.
But there are intellectual conditions which must be in some
measure satisfied before a general assent can be obtained for
novel theories; and the recognized conditions of belief are
peculiarly strained by a theory which suggests that the natural
history of human life is to be found by tracing its origin from
lower levels in the scale of animate existence.