The difference between changes in germ and body The folly of attempting to compare two essentials. The real question is to determine what we get via the road of heredity, what from the environment. The inheritance of physical traits such as dwarfism, deaf- mutism, hemophilia, classification of human beings on basis of mental powers. Feeble-minded, normal, genius. Evidence as to share played by heredity and environment in reproducing these types. The relation of genius and insanity. The frequency of genius. Evidence that desirable traits are inherited. Illustra- tions from royal families of Europe. The rôle of cus- tom and law in controlling marriage. Negative eugenics- the attempt to stop the reproduction of the unfit. Positive eugenics — the attempt to improve the The physical differences between groups of men. Comparison of color of hair, eyes and skin. Stature, fusion of physical and social questions. Various suggested classifications of the human race, from Linnæus to Giddings. Appearance of sex in the organic world. Its ap- parent value. Observed differences between the human mary. IX. THE INFLUENCES OF SOCIETY UPON POPULATION The fertility of different stocks. The falling birth- rate. Influence of medical skill, changed industrial life, immigration, celibacy, disease, contraceptive measures in restricting reproduction. Effect on human physical evolution of inventions, surgical skill, war, religion, charity, social castes, industry, etc. Is inven- tion checking favorable variation and creating an artificial rather than a natural condition? Is science and philanthropy preserving unfavorable types which tend to reproduce faster than the superior and will in time, therefore, drive out the better? Have social ar- rangements destroyed the struggle for existence on which progress depends? Is civilization destroying Belief and knowledge. The rise of customs. Con- flicting moralities. Origin of social institutions Human nature the same in all ages. Progress de- PAGE 311 taining high intellectual standards. The conception of social evolution. The organic theory of society. Spencer. The newer attitude of Sumner and Keller. Theories to account for the rise and downfall of great civilizations. Exact answers cannot be given. Older Comparison of weather conditions Distribution of human energy on the basis of climate Food relations of aquatic animals. Mortality yellow fever - Havana Deaths from tuberculosis and cancer PAGE 16 37 41 Suggested explanation of color inheritance in guinea pigs. 204 Diagram of sex-limited inheritance The relations between successive generations. The inheritance of brachydactylism 210 220 235 |