that some prehistoric stockbreeder, wishing to produce a natural
curiosity, selected the longest-necked animals he could find, and bred
from them until at last an animal with an abnormally long neck was
evolved by intentional selection, just as the race-horse or the fantail
pigeon has been evolved. Both these explanations, you will observe,
involve consciousness, will, design, purpose, either on the part of the
animal itself or on the part of a superior intelligence controlling its
destiny. Darwin pointed out--and this and no more was Darwin's famous
discovery--that a third explanation, involving neither will nor purpose
nor design either in the animal or anyone else, was on the cards. If
your neck is too short to reach your food, you die. That may be the
simple explanation of the fact that all the surviving animals that feed
on foliage have necks or trunks long enough to reach it. So bang goes
your belief that the necks must have been designed to reach the food.
But Lamarck did not believe that the necks were so designed in the
beginning: he believed that the long necks were evolved by wanting
and trying. Not necessarily, said Darwin. Consider the effect on the
giraffes of the natural multiplication of their numbers, as insisted on
by Malthus. Suppose the average height of the foliage-eating animals is
four feet, and that they increase in numbers until a time comes when all
the trees are eaten away to within four feet of the ground. Then the
animals who happen to be an inch or two short of the average will die
of starvation. All the animals who happen to be an inch or so above
the average will be better fed and stronger than the others. They will
secure the strongest and tallest mates; and their progeny will survive
whilst the average ones and the sub-average ones will die out. This
process, by which the species gains, say, an inch in reach, will repeat
itself until the giraffe's neck is so long that he can always find
food enough within his reach, at which point, of course, the selective
process stops and the length of the giraffe's neck stops with it.
Otherwise, he would grow until he could browse off the trees in the
moon. And this, mark you, without the intervention of any stockbreeder,
human or divine, and without will, purpose, design, or even
consciousness beyond the blind will to satisfy hunger. It is true that
this blind will, being in effect a will to live, gives away the whole
case; but still, as compared to