Here, again, the fallacy of capture as primal cause of Avoidance is clearly evident. If this was the case, we might expect it to be almost universal, whereas in reality, instead of the 18 cases which the average should give us, we find only 9. It really had its origin in the reason we have already given, of sexual jealousy as a primary cause, and was later augmented as serving to impress on many the classificatory distinction between M and D, who otherwise, as far as totems went, were eligible to the same person. Where both father-in-law and mother-in-law are in avoidance, we may surmise a change in descent from the F to the M in the tribe, the converse change of M to F of course never occurring. The question of change of descent will explain problems in the nomenclature of Morgan’s tables as regards nephews and sons, which have been overlooked.[17] NOTE TO CHAPTER VII Mr. Crawley reckons three interpretations of the origin of the avoidance of mother-in-law and son-in-law. 1. Fison (_Kamilaroi and Kurnai_, p. 103), ‘It is that the rule is due to a fear of intercourse which is unlawful, though theoretically allowed on some classificatory systems.’ Mr. Crawley remarks, ‘this explanation is the one most likely to occur to explorers who have personal knowledge of savages,’ which was Mr. Atkinson’s case. Mr. Crawley objects the antecedent improbability of any man, ‘not to mention a savage, ever falling in love with a woman old enough to be his mother or mother-in-law, and the improbability of so many peoples being afraid of this.’ Now ‘in love’ is one thing, and an access of lust is another. Moreover, the mother-in-law, in prospective, not infrequently is her daughter’s rival, even in modern life. She has to be guarded against, even if the son-in-law is less dangerous. And he is very apt to be ‘a general lover.’ ‘Theoretically the mother-in-law is marriageable in many systems,’ says Mr. Crawley, ‘and so there would be no incest ...’ But Mr. Atkinson is not contemplating the danger of incest as the cause of mother-in-law avoidance; his theory postulates jealousy--that of the mother-in-law’s husband, and, for what it is worth, that of the mother-in-law’s daughter. Mr. Crawley’s objection, I think, does not invalidate Mr. Atkinson’s theory; especially as he does not reflect that the possible mother-in-law may have a caprice for her son-in-law, while the would-be son-in-law, less frequently, may follow the course of Colonel Henry Esmond. 2. Sir John Lubbock’s (Lord Avebury’s) theory, of enmity caused by capture, Mr. Atkinson has dealt with; it is rejected by Mr. Crawley.