Nor must we overlook the fact, that increased bulk
would act as a protection against almost all beasts of prey excepting the
lion; and against this animal, its tall neck--and the taller the better--
would, as Mr. Chauncey Wright has remarked, serve as a watch-tower. It is
from this cause, as Sir S. Baker remarks, that no animal is more difficult
to stalk than the giraffe. This animal also uses its long neck as a means
of offence or defence, by violently swinging its head armed with stump-like
horns. The preservation of each species can rarely be determined by any
one advantage, but by the union of all, great and small.
Mr. Mivart then asks (and this is his second objection), if natural
selection be so potent, and if high browsing be so great an advantage, why
has not any other hoofed quadruped acquired a long neck and lofty stature,
besides the giraffe, and, in a lesser degree, the camel, guanaco and
macrauchenia? Or, again, why has not any member of the group acquired a
long proboscis? With respect to South Africa, which was formerly inhabited
by numerous herds of the giraffe, the answer is not difficult, and can best
be given by an illustration. In every meadow in England, in which trees
grow, we see the lower branches trimmed or planed to an exact level by the
browsing of the horses or cattle; and what advantage would it be, for
instance, to sheep, if kept there, to acquire slightly longer necks? In
every district some one kind of animal will almost certainly be able to
browse higher than the others; and it is almost equally certain that this
one kind alone could have its neck elongated for this purpose, through
natural selection and the effects of increased use.
Pages:
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349