They made a blunder similar to that of those critics of Utopian Socialism who labor under the pleasing delusion that they are riddling the theories of Marx. Professor Ritchie has preserved a couple of stanzas by a witty Scotch judge who aimed his poem at Darwin, but hit Lamarck.
“A deer with a neck that was longer by half Than the rest of his family, try not to laugh, By stretching and stretching became a giraffe Which nobody can deny.
That four-footed beast which we now call a whale, Held his hind-legs so close that they grew to a tail, Which he uses for threshing the sea, like a flail, Which nobody can deny.”
But Darwin’s theory is altogether independent of the “stretching” idea. The causes and origin of heredity and variation are up to this moment, alike wrapped in mystery. But when science succeeds in penetrating those secrets, it is extremely unlikely that Darwin’s theory will be seriously weakened, no matter what the causes may prove to be.
Now about the giraffe. We will suppose, for the sake of illustration, two giraffes, a male and a female, whose necks are precisely five feet long. We will confine our illustration to the question of the neck alone. We will suppose this particular pair to give birth to a family of three. First comes heredity. All we ask of heredity is that the young shall be giraffes, not camels or any other species; and this heredity guarantees. Now comes variation. As this is an ideal case for the purpose of illustrating the theory, we will have one of the three shorter-necked than the parents, another the same length, while the third has a longer neck--over five feet.
Now comes the struggle for existence. When this family of giraffes is fairly grown and the new-comers are approaching breeding age--mark the importance of this matter of “breeding age,” for the problem is to find out how nature determines which shall be bred from--they are obliged to forage for themselves. There is no pasture to graze; they live in what is almost a desert. There are few shrubs; scarcely anything but fairly high trees--from ten to twenty feet. If a giraffe breeder had this matter in hand and he wished to increase the length of the giraffe’s neck, the problem would be simple. He would select number three with the longest neck, pair it with the longest necked member of the opposite sex in some other family and the trick would be done. But this is in Central Africa, where there is no breeder to interfere, and the question is: can nature accomplish the same result without his help?