Evolution Social and Organic

by Arthur M. Lewis

However that may be, it is quite clear that the germ-plasm theory completely shuts out the Lamarckian factor of evolution in all cases where propagation is sexual.

“But,” say the Neo-Lamarckians, “Darwinism in itself, merely assumes variations without attempting to explain their origin. Natural selection only explains the survival of the fittest; it tells us nothing of what Prof. Cope calls the ‘Origin of the Fittest.’ There must be variation before selection, whence then, comes this variation?” To this question Weismann has a ready reply. “Variation is due to the blending of two wholly different kinds of germ-plasm at conception, producing at birth a result that is not, and cannot be, wholly like the contributor of either.”

And now, at last, the great German is in a corner. If all variations are due to congenital characters only, and these, of course, are only possible because of the combinations secured by sexual reproduction, how do variations arise among non-sexual organisms where such combinations cannot exist?

This is indeed, a poser. But any rejoicing by Weismann’s opponents is quite premature. The sagacity which set those opponents by the ears is still available. There is no attempt to untie that knot; Weismann cuts it with a knife. He empties his antagonist’s sails by a smiling and gracious surrender. Below the sexually reproducing animals, he concedes the operation of the Lamarckian factor. In that unicellular world it is not a special cell that is passed on but the individual itself is continued, and of course any character acquired by the individual will be preserved along with the individual.

Thus then the region of controversy is limited to sexually reproducing organisms and we come to the field where the fiercest fight was made. Do these organisms transmit by heredity those characters or peculiarities acquired by the individual during its own life-time? To this question the Neo-Lamarckians gave a positive affirmative, which Weismann met with an unwavering denial.

Weismann challenged his opponents to produce a single demonstration of such a transmission. Here let us be clear as to what is meant by an acquired character. For illustration, let us suppose a father leaves his son an estate of a thousand acres. That is inheritance. If the son leaves his son the same one thousand acres, that is still inheritance. But if that son increases the estate, during his life-time to two thousand, the second thousand is an “acquired character” of a property nature. There the analogy ceases for there is no dispute as to his ability to transmit both thousands to his heirs by inheritance.

But with “acquired characters” of a biological nature, Weismann maintains this to be impossible. Many specific instances were put forward in refutation of this contention. Herbert Spencer cited the case of the supposed degeneration of the little toe in civilized man as a result of the shoe wearing habit. This it was urged could only have occurred through the transmission of acquired characters and not by natural selection as this diminished toe could not be of any value in the struggle for existence.

But it was shown by measuring the feet of savages, who do not wear shoes, and whose ancestors never wore them, that the small toes of savages had degenerated quite as much.

Then Cesare Lombroso entered the arena leading a camel. According to the Italian criminologist, the camel’s hump had been first acquired by bearing loads and then transmitted by heredity. From the fact that the camel and the llama, which is smooth backed, have something in common, he concludes that camels are really llamas that have recently acquired a hump in the performance of their labors. Lombroso also supported his hump theory by some statements about Hottentot women having developed callouses on their hips by carrying their children on their backs. Unfortunately all Lombroso’s ingenuity was wasted for we happen to possess the geological record of the camel in good condition, and from this history we know that the “ship of the desert” had his hump before the human race appeared when according to Lombroso he should have been a smooth-backed llama. Disappointed as Weismann’s critics were it was hardly feasible to argue that the camel had gotten his hump in those early times by placing loads on his own back.

It was clearly seen that if a case of the transmission of a mutilation could be established, Weismann’s theory would be thereby demolished. A remarkable attempt was made in this direction in 1887 at the meeting of the Association of the German Naturalists at Wiesbaden. To that dignified gathering came Dr. Zacharias with a number of tailless cats. It was asserted that these cats had no tails because their mother had lost her tail through having it run over by a cart wheel. The examination of these specimens proved an entertaining diversion from the regular proceedings, and Prof. Eimer took them seriously enough to refer to them in a later work as “a valuable instance of the transmission of mutilations.”