Contributions to the theory of natural selection. A series of essays ... By Alfred Russel Wallace ...

206 ON INSTINCT IN MAN AND ANLIMALS.
Does Al]an possess Jlzstincts.
Many of the upholders of the instinctive theory
maintain, that man has instincts exactly of the same
nature as those of animals, but more or less liable to
be obscured by his reasoning powers; and as this is
a case more open to our observation than any other,
I will devote a few pages to its consideration. Infants
are said to suck by instinct, and afterwards to walk
by the same power, while in adult man the most prominent case of instinct is supposed to be, the powers
possessed by savage races to find their way across a
trackless and previously unknown wilderness. Let
us take first the case of the infant's sucking. It is
sometimes absurdly stated that the new-born infant'~ seeks the breast," and this is held to be a wonderful
proof of instinct. No doubt it would be if true, but
unfortunately for the theory it is totally false, as
every nurse and medical man can testify. Still, the
child undoubtedly sucks without teaching, but this is
one of those simple acts dependent upon organization,
which cannot properly be termed instinct, any more
than breathing or muscular motion. Any object of
suitable size in the mouth of an infant excites the
nerves and muscles so as to produce the act of suction,
and when at a little later period, the will comes into
play, the pleasurable sensations consequent on the act
lead to its continuance. So, walking is evidently dependent on the arrangement of the bones and joints,
and the pleasurable exertion of the muscles, which