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Descent of Man [ 1871]

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Author Topic: Descent of Man [ 1871]  (Read 2932 times)
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« Reply #180 on: February 10, 2009, 01:22:20 pm »

Male quadrupeds, which are furnished with tusks, use them in various
ways, as in the case of horns. The boar strikes laterally and upwards;
the musk-deer downwards with serious effect.* The walrus, though
having so short a neck and so unwieldy a body, "can strike either
upwards, or downwards, or sideways, with equal dexterity."*(2) I was
informed by the late Dr. Falconer, that the Indian elephant fights
in a different manner according to the position and curvature of his
tusks. When they are directed forwards and upwards he is able to fling
a tiger to a great distance- it is said to even thirty feet; when they
are short and turned downwards he endeavours suddenly to pin the tiger
to the ground and, in consequence, is dangerous to the rider, who is
liable to be jerked off the howdah.*(3)

  * Pallas Spicilegia Zoologica, fasc. xiii., 1779, p. 18.
  *(2) Lamont, Seasons with the Sea-Horses, 1861, p. 141.
  *(3) See also Corse (Philosophical Transactions, 1799, p. 212) on
the manner in which the short-tusked Mooknah variety attacks other

  Very few male quadrupeds possess weapons of two distinct kinds
specially adapted for fighting with rival males. The male muntjac-deer
(Cervulus), however, offers an exception, as he is provided with horns
and exserted canine teeth. But we may infer from what follows that one
form of weapon has often been replaced in the course of ages by
another. With ruminants the development of horns generally stands in
an inverse relation with that of even moderately developed canine
teeth. Thus camels, guanacoes, chevrotains, and musk-deer, are
hornless, and they have efficient canines; these teeth being "always
of smaller size in the females than in the males." The Camelidae have,
in addition to their true canines, a pair of canine-shaped incisors in
their upper jaws.* Male deer and antelopes, on the other hand, possess
horns, and they rarely have canine teeth; and these, when present, are
always of small size, so that it is doubtful whether they are of any
service in their battles. In Antilope montana they exist only as
rudiments in the young male, disappearing as he grows old; and they
are absent in the female at all ages; but the females of certain other
antelopes and of certain deer have been known occasionally to
exhibit rudiments of these teeth.*(2) Stallions have small canine
teeth, which are either quite absent or rudimentary in the mare; but
they do not appear to be used in fighting, for stallions bite with
their incisors, and do not open their mouths wide like camels and
guanacoes. Whenever the adult male possesses canines, now inefficient,
whilst the female has either none or mere rudiments, we may conclude
that the early male progenitor of the species was provided with
efficient canines, which have been partially transferred to the
females. The reduction of these teeth in the males seems to have
followed from some change in their manner of fighting, often (but
not in the horse) caused by the development of new weapons.

  * Owen, Anatomy of Vertebrates, vol. iii., p. 349.
  *(2) See Ruppell (in Proc. Zoolog. Soc., Jan. 12, 1836, p. 3) on the
canines in deer and antelopes, with a note, by Mr. Martin on a
female American deer. See also Falconer (Palaeont. Memoirs and
Notes, vol. i., 1868, p. 576) on canines in an adult female deer. In
old males of the musk-deer the canines (Pallas, Spic. Zoolog., fasc.
xiii., 1779, p. 18) sometimes grow to the length of three inches,
whilst in old females a rudiment projects scarcely half an inch
above the gums.

  Tusks and horns are manifestly of high importance to their
possessors, for their development consumes much organised matter. A
single tusk of the Asiatic elephant- one of the extinct woolly
species- and of the African elephant, have been known to weigh
respectively 150, 160, and 180 pounds; and even greater weights have
been given by some authors.* With deer, in which the horns are
periodically renewed, the drain on the constitution must be greater;
the horns, for instance, of the moose weigh from fifty to sixty
pounds, and those of the extinct Irish elk from sixty to seventy
pounds- the skull of the latter weighing on an average only five
pounds and a quarter. Although the horns are not periodically
renewed in sheep, yet their development, in the opinion of many
agriculturists, entails a sensible loss to the breeder. Stags,
moreover, in escaping from beasts of prey are loaded with an
additional weight for the race, and are greatly retarded in passing
through a woody country. The moose, for instance, with horns extending
five and a half feet from tip to tip, although so skilful in their use
that he will not touch or break a twig when walking quietly, cannot
act so dexterously whilst rushing away from a pack of wolves.
"During his progress he holds his nose up, so as to lay the horns
horizontally back; and in this attitude cannot see the ground
distinctly."*(2) The tips of the horns of the great Irish elk were
actually eight feet apart! Whilst the horns are covered with velvet,
which lasts with red-deer for about twelve weeks, they are extremely
sensitive to a blow; so that in Germany the stags at this time
somewhat change their habits, and avoiding dense forests, frequent
young woods and low thickets.*(3) These facts remind us that male
birds have acquired ornamental plumes at the cost of retarded
flight, and other ornaments at the cost of some loss of power in their
battles with rival males.

  * Emerson Tennent, Ceylon, 1859, vol. ii., p. 275; Owen, British
Fossil Mammals, 1846, p. 245.
  *(2) Richardson, Fauna Bor. Americana, on the moose, Alces
palmata, pp. 236, 237; on the expanse of the horns, Land and Water,
1869, p. 143. See also Owen, British Fossil Mammals, on the Irish elk,
pp. 447, 455.
  *(3) Forest Creatures, by C. Boner, 1861, p. 60.

  With mammals, when, as is often the case, the sexes differ in
size, the males are almost always larger and stronger. I am informed
by Mr. Gould that this holds good in a marked manner with the
marsupials of Australia, the males of which appear to continue growing
until an unusually late age. But the most extraordinary case is that
of one of the seals (Callorhinus ursinus), a full-grown female
weighing less than one-sixth of a full-grown male.* Dr. Gill remarks
that it is with the polygamous seals, the males of which are well
known to fight savagely together, that the sexes differ much in
size; the monogamous species differing but little. Whales also
afford evidence of the relation existing between the pugnacity of
the males and their large size compared with that of the female; the
males of the right-whales do not fight together, and they are not
larger, but rather smaller, than their females; on the other hand,
male sperm-whales fight much together, and their bodies are "often
found scarred with the imprint of their rival's teeth," and they are
double the size of the females. The greater strength of the male, as
Hunter long ago remarked,*(2) is invariably displayed in those parts
of the body which are brought into action in fighting with rival
males- for instance, in the massive neck of the bull. Male
quadrupeds are also more courageous and pugnacious than the females.
There can be little doubt that these characters have been gained,
partly through sexual selection, owing to a long series of
victories, by the stronger and more courageous males over the
weaker, and partly through the inherited effects of use. It is
probable that the successive variations in strength, size, and
courage, whether due to mere variability or to the effects of use,
by the accumulation of which male quadrupeds have acquired these
characteristic qualities, occurred rather late in life, and were
consequently to a large extent limited in their transmission to the
same sex.
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