First and foremost, it will give genetics a chance to advance with more rapidity, in its study of man. Genetics, the study of heredity, can not successfully proceed by direct observation in the human species as it does with plants and rapidly-breeding animals, because the generations are too long. Less than three generations are of little value for genetic researches, and even three can rarely be observed to advantage by any one person. Therefore, second-hand information must be used. So far, most of this has been gained by sending field-workers—a new kind of genealogist—out among the members of a family, and having them collect the desired information, either by study of extant records, or by word of mouth. But the written records of value have been usually negligible in quantity, and oral communication has therefore been the mainstay. It has not been wholly satisfactory. Few people—aside from genealogists—can give even the names of all their great-grandparents, far less can they tell anything of importance about them.
It is thus to genealogy that genetics is driven. Unless family records are available, it can accomplish little. And it can not get these family records unless genealogists realize the importance of furnishing them; for as has already been pointed out, most genealogies at present available are of little value to genetics, because of the inadequacy of the data they furnish. It is only in the case of exceptional families, such as the royal houses of Europe, that enough information is given about each individual to furnish an opportunity for analysis. What could be done if there were more such data available is brilliantly illustrated in the investigation by Frederick Adams Woods of Boston of the reigning houses of Europe. His writings should be read by every genealogist, as a source of inspiration as well as information.
More such data must be obtained in the future. Genealogists must begin at once to keep family records in such a way that they will be of the greatest value possible—that they will serve not only family pride, but bigger purposes. It will not take long to get together a large number of family histories, in which the idea will be to tell as much as possible, instead of as little as possible, about every individual mentioned.
The value of pedigrees of this kind is greater than most people realize.
In the first place, it must be remembered that these traits, on whose importance in the pedigree we have been insisting, are responsible not only for whatever the individual is, but for whatever society is,—whatever the race is. They are not personal matters, as C. B. Davenport and H. H. Laughlin well point out; "they come to us from out of the population of the past, and, in so far as we have children, they become disseminated throughout the population of the future. Upon such traits society is built; good or bad they determine the fate of our society. Apart from migration, there is only one way to get socially desirable traits into our social life, and that is reproduction; there is only one way to get them out, by preventing the reproduction. All social welfare work is merely education of the germs of traits; it does not provide such germs. In the absence of the germs the traits can not develop. On the other hand, it is possible with difficulty, if possible at all, by means of the strongest repressive measures merely, to prevent the development of undesirable hereditary traits. Society can treat the delinquent individual more reasonably, more effectively, and more humanely, if it knows the 'past performance' of his germ-plasm."
In addition to their importance to society, a knowledge of the traits of a pedigree has a great direct importance to the individual; one of the most valuable things to be learned from that knowledge is the answer to the question, "What shall a boy or girl do? What career shall one lay out for one's children?" A knowledge of the child's inborn nature, such as can be had only through study of his ancestry, will guide those who have his education in hand, and will further guide those who decide, or help the child decide, what work to take up in life. This helps to put the problem of vocational guidance on a sound basis,—the basis of the individual's inherent aptitudes.
Not too much must be expected from vocational guidance at the present time, but in the case of traits that are inherited, it is a fair inference that a child is more likely to be highly endowed with a trait which both parents possess, than with one that only one parent possesses. "Among the traits which have been said to occur in some such direct hereditary way," H. L. Hollingworth[164] observes, "or as the result of unexplained mutation or deviation from type, are: mathematical aptitude, ability in drawing,[165] musical composition,[166] singing, poetic reaction, military strategy, chess playing. Pitch discrimination seems to depend on structural factors which are not susceptible of improvement by practice.[167] The same may be said of various forms of professional athletic achievement. Color blindness seems to be an instance of the conspicuous absence of such a unit characteristic."
Again, the knowledge of ancestry is an essential factor in the wise selection of a husband or wife. Insistence has been laid on this point in an earlier chapter of this book, and it is not necessary here to repeat what was there said. But it seems certain that ancestry will steadily play a larger part in marriage selection in the future; it is at least necessary to know that one is not marrying into a family that carries the taint of serious hereditary defect, even if one knows nothing more. An intelligent study of genealogy will do much, we believe, to bring about the intelligent selection of the man or woman with whom one is to fall in love.
In addition to these general considerations, it is evident that genealogy, properly carried out, would throw light on most of the specific problems with which eugenics is concerned, or which fall in the field of genetics. A few examples of these problems may be mentioned, in addition to those which are discussed in various other chapters of this book.