In opposition to the theory of McLennan various explanations of the origin of polyandry have been advanced. Spencer regards both polygyny and polyandry as mere limitations of promiscuity. "Promiscuity may be called indefinite polyandry joined with indefinite polygyny; and one mode of advance is by diminution of the indefiniteness." Polyandry, therefore, does not originate in scarcity of women; nor can it be due to poverty; "though poverty may, in some cases, be the cause of its continuance and spread." It is rather one of several independent "types of marital relations emerging from the primitive unregulated state; and one which has survived where competing forms, not favored by the conditions, have failed to extinguish it."[407] Hellwald holds a similar view.[408] Robertson Smith traces its origin to the practice of capturing or of purchasing wives in common by a group of kinsmen; and in the case of purchase, poverty or the high price of women must have exerted a favorable influence.[409] Not entirely dissimilar is the view of Wake who, rejecting the hypothesis of McLennan, believes that polyandry can be satisfactorily explained "only as being established, under the pressure of poverty, either independently or as an offshoot from the phase of punaluan group marriage in which several brothers have their wives in common."[410] Starcke in like manner finds that it "is adapted in every respect to this organization of the joint family group." In its highest forms "it is only the eldest brother who is married," and "the younger ones are not husbands, but merely specially authorized lovers. There is nothing to indicate that the band of brothers, as such, take a wife in common; that is, that the marriage is the act of the whole community." Hence "polyandry belongs to the category of facts which have to do with the ordinary family communism;" and it does not forfeit its character of a marriage in which the individual does not quite lose his personality in the group.[411] [407] SPENCER, _Principles of Sociology_, I, 673-75, 678, 679. Insufficient food-supply may cause polygynic and monogamic families to die out; and it is favorable to the survival of the polyandrous family. But the infertility of polyandrous families is unfavorable to their survival, for there are fewer members available for defense.--_Ibid._, 681.