The Descent of Man and Selection in Relation to Sex, Vol. IDarwin, Charles
Science
The Descent of Man and Selection in Relation to Sex, Vol. I
Darwin, Charles
Evolution (Biology); Human beings -- Origin; Sex differences; Sexual dimorphism (Animals); Sexual selection in animals
The celebrated sculptor, Mr. Woolner, informs me of one little
peculiarity in the external ear, which he has often observed both in men
and women, and of which he perceived the full signification. His
attention was first called to the subject whilst at work on his figure
of Puck, to which he had given pointed ears. He was thus led to examine
the ears of various monkeys, and subsequently more carefully those of
man. The peculiarity consists in a little blunt point, projecting from
the inwardly folded margin, or helix. Mr. Woolner made an exact model of
one such case, and has sent me the accompanying drawing. (Fig. 2.) These
points not only project inwards, but often a little outwards, so that
they are visible when the head is viewed from directly in front or
behind. They are variable in size and somewhat in position, standing
either a little higher or lower; and they sometimes occur on one ear and
not on the other. Now the meaning of these projections is not, I think,
doubtful; but it may be thought that they offer too trifling a character
to be worth notice. This thought, however, is as false as it is natural.
Every character, however slight, must be the result of some definite
cause; and if it occurs in many individuals deserves consideration. The
helix obviously consists of the extreme margin of the ear folded
inwards; and this folding appears to be in some manner connected with
the whole external ear being permanently pressed backwards. In many
monkeys, which do not stand high in the order, as baboons and some
species of macacus,[27] the upper portion of the ear is slightly
pointed, and the margin is not at all folded inwards; but if the margin
were to be thus folded, a slight point would necessarily project inwards
and probably a little outwards. This could actually be observed in a
specimen of the _Ateles beelzebuth_ in the Zoological Gardens; and we
may safely conclude that it is a similar structure—a vestige of
formerly pointed ears—which occasionally reappears in man.
The nictitating membrane, or third eyelid, with its accessory muscles
and other structures, is especially well developed in birds, and is of
much functional importance to them, as it can be rapidly drawn across
the whole eye-ball. It is found in some reptiles and amphibians, and in
certain fishes, as in sharks. It is fairly well developed in the two
lower divisions of the mammalian series, namely, in the monotremata and
marsupials, and in some few of the higher mammals, as in the walrus. But
in man, the quadrumana, and most other mammals, it exists, as is
admitted by all anatomists, as a mere rudiment, called the semilunar
fold.[28]
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