The Physical Basis of Society

acres Africa America appears areas Asia atoms average bacteria believe birds body carbon carbon dioxide cause cent century cephalic index changes characters chromosomes civilization climate color common copper crops cultivated culture danger Darwin death rate destroy disease domestic early earth eggs environment Europe European evidence fact feeble-minded females fish forms germ cells given heredity human Ibid important increase Indians individual inheritance insane insects iron killed known land later light living male man's marriage metals miles natural selection nature Negro neolithic organisms ovum oxygen Pará rubber tree parasites physical population possible pounds present problems produced R. S. LULL race seeds seems social South South America species square mile supply T. H. MORGAN temperature things thousand tion to-day trees tropics types United wild woman women