CHAPTER IX

THE REGULATION OF NUMBERS 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(1) The theory of Malthus has long been disproved, and (2) has been replaced by the modern theory of an optimum density of population. (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 intercourse, 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.