Selection and Race 199
The causes that check the unlimited improvement of highly-bred animals, so long as the race remains unchanged, are many and absolute.
In the first place there is an increasing delicacy of constitution; the growing fineness of limb and structure end, after a few generations, in fragility. Overbred animals have little stamina; they resemble in this respect the “weedy” colts so often reared from first-class racers. One can perhaps see in a general way why this should be so. Each individual is the outcome of a vast number of organic elements of the most various species, just as some nation-might be the outcome of a vast number of castes of individuals, each caste monopolising a special pursuit. Banish a number of the humbler castes—the bakers, the bricklayers,. and the smiths, and the nation would soon come to grief. This is what is done in high breeding; certain qualities are bred for, and the rest are diminished as far as possible, but they cannot be dispensed with entirely.
The next difficulty lies in the diminished fertility of highly-bred animals. It is not improbable that its cause is of the same character as that of the delicacy of their constitution. Together with infertility is combined some degree of sexual indifference, or when passion is shown, it is not unfrequently for some specimen of a coarser type. This is certainly the case with horses and with dogs.
It will be easily understood that these difficulties, which are so formidable in the case of plants and animals, which we can mate as we please and destroy when we please, would make the maintenance of a highly-selected breed of men an impossibility.
Whenever a low race is preserved under conditions of life that exact a high level of efficiency, it must be subjected to rigorous selection. The few best specimens of that race can alone be allowed to become parents, and not many of their descendants can be allowed to live. On the other hand; if a higher race be substituted for the low one, all this terrible misery disappears. The most merciful form of what I ventured to call “eugenics” would consist in watching for the indications of superior strains or races, and in so favoring them that their progeny shall outnumber and gradually’
