Message #128504

[Bullseye]

 * For instance, M. Richard (Annales des Sciences Nat., 3d series,
Zoolog., 1852, tom. xviii., p. 13) describes and figures rudiments
of what he calls the "muscle pedieux de la main," which he says is
sometimes "infiniment petit." Another muscle, called "le tibial
posterieur," is generally quite absent in the hand, but appears from
time to time in a more or less rudimentary condition.
  *(2) Prof. W. Turner, Proceedings of the Royal Society of Edinburgh,
1866-67, p. 65.

  Some few persons have the power of contracting the superficial
muscles on their scalps; and these muscles are in a variable and
partially rudimentary condition. M.A. de Candolle has communicated
to me a curious instance of the long-continued persistence or
inheritance of this power, as well as of its unusual development. He
knows a family, in which one member, the present head of the family,
could, when a youth, pitch several heavy books from his head by the
movement of the scalp alone; and he won wagers by performing this
feat. His father, uncle, grandfather, and his three children possess
the same power to the same unusual degree. This family became
divided eight generations ago into two branches; so that the head of
the above-mentioned branch is cousin in the seventh degree to the head
of the other branch. This distant cousin resides in another part of
France; and on being asked whether he possessed the same faculty,
immediately exhibited his power. This case offers a good
illustration how persistent may be the transmission of an absolutely
useless faculty, probably derived from our remote semi-human
progenitors; since many monkeys have, and frequently use the power, of
largely moving their scalps up and down.*

  * See my Expression of the Emotions in Man and Animals, 1872, p.
144.

  The extrinsic muscles which serve to move the external ear, and
the intrinsic muscles which move the different parts, are in a
rudimentary condition in man, and they all belong to the system of the
panniculus; they are also variable in development, or at least in
function. I have seen one man who could draw the whole ear forwards;
other men can draw it upwards; another who could draw it backwards;*
and from what one of these persons told me, it is probable that most
of us, by often touching our ears, and thus directing our attention
towards them, could recover some power of movement by repeated trials.
The power of erecting and directing the shell of the ears to the
various points of the compass, is no doubt of the highest service to
many animals, as they thus perceive the direction of danger; but I
have never heard, on sufficient evidence, of a man who possessed
this power, the one which might be of use to him. The whole external
shell may be considered a rudiment, together with the various folds
and prominences (helix and anti-helix, tragus and anti-tragus, &c.)
which in the lower animals strengthen and support the ear when
erect, without adding much to its weight. Some authors, however,
suppose that the cartilage of the shell serves to transmit
vibrations to the acoustic nerve; but Mr. Toynbee,*(2) after
collecting all the known evidence on this head, concludes that the
external shell is of no distinct use. The ears of the chimpanzee and
orang are curiously like those of man, and the proper muscles are
likewise but very slightly developed.*(3) I am also assured by the
keepers in the Zoological Gardens that these animals never move or
erect their ears; so that they are in an equally rudimentary condition
with those of man, as far as function is concerned. Why these animals,
as well as the progenitors of man, should have lost the power of
erecting their ears, we can not say. It may be, though I am not
satified with this view, that owing to their arboreal habits and great
strength they were but little exposed to danger, and so during a
lengthened period moved their ears but little, and thus gradually lost
the power of moving them. This would be a parallel case with that of
those large and heavy birds, which, from inhabiting oceanic islands,
have not been exposed to the attacks of beasts of prey, and have
consequently lost the power of using their wings for flight. The
inability to move the ears in man and several apes is, however, partly
compensated by the freedom with which they can move the head in a
horizontal plane, so as to catch sounds from all directions. It has
been asserted that the ear of man alone possesses a lobule; but "a
rudiment of it is found in the gorilla";*(4) and, as I hear from Prof.
Preyer, it is not rarely absent in the negro.

  * Canestrini quotes Hyrtl. (Annuario della Soc. dei Naturalisti,
Modena, 1897, p. 97) to the same effect.
  *(2) The Diseases of the Ear, by J. Toynbee, F. R. S., 1860, p.
12. A distinguished physiologist, Prof. Preyer, informs me that he had
lately been experimenting on the function of the shell of the ear, and
has come to nearly the same conclusion as that given here.
  *(3) Prof. A. Macalister, Annals and Magazine of Natural History,
vol. vii., 1871, p. 342.
  *(4) Mr. St. George Mivart, Elementary Anatomy, 1873, p. 396.