364 Life and Letters of Francis Galton
The whole work is prefaced with an account by Galton of how the Record should be filled in. It contains many characteristic statements. A few of these may be cited here, as the book is very scarce.
"This book is designed for those who care to forecast the mental and bodily faculties of their children, and to further the science of heredity. The natural gifts of each individual being inherited from his ancestry, it is possible to foresee much of the latent capacities of a child in mind and body, of the probabilities of his future health and longevity, and of his tendencies to special forms of disease, by a knowledge of his ancestral precedents. When the science of heredity shall have become more advanced, the accuracy of such forecasts will doubtless improve; in the meantime we may rest assured that fewer blunders will be made in rearing and educating children, under the guidance of a knowledge of their family antecedents,
than without it."
In the third paragraph Galton rightly points out that it is needful to study as many ancestral lines as possible, and that the book gives no countenance to the vanity that prompts most family historians to trace their pedigree to some notable ancestor and to pass over the rest in silence. Galton remarks that
" one ancestor who lived at the time of the Norman Conquest, twenty-four generations back, contributes (on the supposition of no intermarriage of kinsfolk) less than one part in 16,000,000 to the constitution of a man of the present day." (p. 1.)
This is rather a theoretical than an observational result. It is true a man may have 20 to 30 generations back 16,000,000 direct line ancestors if so many were available, but it is equally true that a distinguished man of that day might have several million descendants, and, if any system of alternative or factorial inheritance be true, the distinguished individuals among those descendants may owe their nature to that distinguished ancestor. It does mean something to trace even in one line-and there are four or five-a link between Darwin or Galton and Alfred the Great. It signifies nothing to trace the same link between a mediocrity and Alfred the Great'. Galton suggests that we need not go back beyond our great-grandparents, and this is absolutely true of characters which blend. But when he tells us that if an alien element of race or disease has been introduced into a family-a touch of Hebrew, of Huguenot (or even negroid) blood-it may be traced far further, he seems to me to be contradicting his previous statement. Albinism for example may remain latent through far more than three generations. But Galton recognises fully this latency at other points.
"Brothers and sisters are alike in blood, but it commonly happens that one of them exhibits some faculty in a conspicuous degree, which exists only in a latent form in another, and which the latter is, perhaps, equally capable of transmitting to his children. Therefore records of the faculties of the brothers and sisters of direct ancestors are of great value in
disclosing hidden characteristics." (p. 2.)
I think it would be more just to say that the limitation to great-grandparents is only a question of the limitation of knowledge in the case of most families ; and without being conclusive a great deal may still be learnt, if we
' The illustration can be given in another form: Some 15 years ago piebaldism appeared in my stirp of dogs and soon disappeared. After 7 or 8 generations it has reappeared. The piebald ancestor means little to the average dog of my stock ; he means everything to the
isolated piebald puppies of to-day.