10 CONTENTS 



CHAPTEE IX 



PAGE 



THE REGULATION OF NTOIBERS AMONG PRIMITIVE RACES 197 



(1) The theory of Malthus has long been disproved, and (2) has 

 been replaced by the modern theory of an optimum density of popula- 

 tion. (3) Territories are strictly defined among hunting and fishing 

 races, and (4) among primitive agricultural races. (5) Among all 

 these races there is co-operation in the search for food. (6) The 

 principle of the optimum number holds good for all of them, and by 

 the natural selection of customs, practices restrictive of increase 

 come everywhere into use in the shape of abstention from inter- 

 course, abortion, and infanticide. (7) Evidence of these practices is 

 incomplete, (8) but shows that they are so practised as to keep 

 numbers down to a certain level, (9) and, though they may be adjusted 

 solely by natural selection, yet some semi-conscious adjustment may 

 take place. (10) That adjustment should take place, a certain standard 

 of skill is necessary on the part of those who set up new families and 

 is ensured by marriage customs. (11) General conditions of savage 

 life afford evidence that customs are effective. (12) There is no 

 correlation between these practices and economic stages ; though 

 evidence is lacking, the presumption is that some such practices 

 were everywhere in use (13) not only among primitive but also 

 among prehistoric races, (14) who have moved slowly away from 

 the conditions prevalent in the intermediate stage. 



CHAPTEE X 



HISTORICAL RACES 243 



(1) These races fall under four sub-headings. For all of them the 

 evidence is discussed concerning (2) disease, (3) warfare, (4) and 

 child mortality. (5) In sub-groups 1 and 2 celibacy and postpone- 

 ment of marriage, (6) pre-puberty marriage, (7) lactation, (8) restraint 

 from intercourse, (9) contraceptive practices, (10) size of family, 

 (11) abortion, (12) and infanticide. (13) In sub-groups 3 and 4 pre- 

 puberty intercourse and lactation, (14) celibacy and marriage, 

 (15) contraceptive practices, (16) abortion and infanticide, (17) and 

 venereal disease. 



CHAPTEE XI 

 THE REGULATION OF NUMBERS AMONG HISTORICAL RACES 270 



(1) Among these races, in spite of certain complications, the 

 principle of the optimum number holds good. (2) The evidence for 

 the first sub-group is too scanty to base conclusions upon. (3) 

 Among the races of the second sub-group we see how the pressure 

 is felt, and (4) we have knowledge of the factors at work, but (5) in 



