I thought my students might be interested in this quotation from Charles Darwin's
The Descent of Man, chapter 4:
Nevertheless
the difference in mind between man and the higher animals, great as it is,
certainly is one of degree and not of kind.
We have seen that the senses and intuitions, the various emotions and
faculties, such as love, memory, attention, curiosity, imitation, reason,
&c., of which man boasts, may be found in an incipient, or even sometimes
in a well-developed condition, in the lower animals. They are also capable of
some inherited improvement, as we see in the domestic dog compared with the wolf
or jackal. If it could be proved that certain high mental powers, such as the
formation of general concepts, self-consciousness, &c., were absolutely
peculiar to man, which seems extremely doubtful, it is not improbable that these
qualities are merely the incidental results of other highly-advanced
intellectual faculties; and these again mainly the result of the continued use
of a perfect language.
At
what age does the new-born infant possess the power of abstraction, or become self-conscious,
and reflect on its own existence? We cannot answer; nor can we answer in regard
to the ascending organic scale. The half-art, half-instinct of language still
bears the stamp of its gradual evolution. The ennobling belief in God is not
universal with man; and the belief in spiritual agencies naturally follows from
other mental powers. The moral sense perhaps affords the best and highest distinction
between man and the lower animals; but I need say nothing on this head, as I
have so lately endeavoured to shew that the social instincts,- the prime
principle of man's moral constitution* - with the aid of active intellectual
powers and the effects of habit, naturally
lead to the golden rule, "As ye would that men should do to you, do ye to
them likewise"; and this lies at the foundation of morality.
* Marcus Aurelius, Meditations, Bk. V, sect.
55.