Fortunately, the pedigree was fairly full and several lines of it could be carried through the sixth generation. There was, indeed, a considerable amount of consanguineous marriage involved. When the amount of inbreeding represented by these blind boys was measured, it proved to be almost identical with the amount represented by the present Kaiser of Germany.[93]
We are unable to see in such a history as that of Hopetown, Bahama Islands, any evidence that consanguineous marriage necessarily results in degeneracy. Dr. Penrose himself points to a potent factor when he says of his chart in another connection: "It will be noticed that only a few of the descendants of Widow Malone [the first settler at Hopetown] are indicated as having married. By this it is not meant that the others did not marry; many of them did, but they moved away and settled elsewhere, and in no way affected the future history of the settlement of Hopetown."
By moving away, it appears to us, they did very decidedly affect the future history of Hopetown. Who are the emigrants? Might they not have been the more enterprising and intelligent, the physically and mentally superior of the population, who rebelled at the limited opportunities of their little village, and went to seek a fortune in some broader field? Did not the best go in general; the misfits, the defectives, stay behind to propagate? Emigration in such a case would have the same effect as war; it would drain off the best stock and leave the weaklings to stay home and propagate their kind. Under such conditions, defectives would be bound to multiply, regardless of whether or not the marriages are consanguineous.
"It will be seen at a glance," Dr. Penrose writes, "that early in the history of the Malone family these indications of degeneracy were absent; but they began in the fourth generation and rapidly increased afterward until they culminated by the presence of five idiots in one family. The original stock was apparently excellent, but the present state of the descendants is deplorable."
Now three generations of emigration from a little community, which even to-day has only 1,000 inhabitants, would naturally make quite a difference in the average eugenic quality of the population. In almost any population, a few defectives are constantly being produced. Take out the better individuals, and leave these defectives to multiply, and the amount of degeneracy in the population will increase, regardless of whether the defectives are marrying their cousins, or unrelated persons. The family of five idiots, cited by Dr. Penrose, is an excellent illustration, for it is not the result of consanguineous marriage—at least, not in a close enough degree to have appeared on the chart. It is doubtless a mating of like with like; and biologically, consanguineous marriage is nothing more.
Honesty demands, therefore, that consanguineous marriage be not credited with results for which the consanguineous element is in no wise responsible. The prevailing habit of picking out a community or a strain where consanguineous marriage and defects are associated and loudly declaring the one to be the cause of the other, is evidence of the lack of scientific thought that is all too common.
Most of the studies of these isolated communities where intermarriage has taken place, illustrate the same point. C. B. Davenport, for example, quotes[94] an anonymous correspondent from the island of Bermuda, which "shows the usual consequence of island life." He writes: "In some of the parishes (Somerset and Paget chiefly) there has been much intermarriage, not only with cousins but with double first cousins in several cases. Intermarriage has chiefly caused weakness of character leading to drink, not lack of brains or a certain amount of physical strength, but a very inert and lazy disposition."
It is difficult to believe that anyone who has lived in the tropics could have written this except as a practical joke. Those who have resided in the warmer parts of the world know, by observation if not by experience, that a "weakness of character leading to drink" and "an inert and lazy disposition" are by no means the prerogatives of the inbred.
If one is going to credit consanguineous marriage with these evil results, what can one say when evil results fail to follow?
What about Smith's Island, off the coast of Maryland, where all the inhabitants are said to be interrelated, and where a physician who lived in the community for three years failed to find among the 700 persons a single case of idiocy, insanity, epilepsy or congenital deafness?