The recent contentions of Westermarck in regard to monogamy among anthropoid apes are far from proving anything.
Prof. Westermarck traces it to a horror of blood; very probably; but other things may co-operate towards it.
Westermarck regards this as one of the fundamental elements in the beginnings of morality.
For in that case they could have had (we are to fancy) no erotic desires towards each other; that is Dr. Westermarck's idea.
Westermarck derived most of his materials for the study of marriage from ethnological materials.
Even at Dr. Westermarck's stage of the dawn of barter, 'marriage by capture must have been very common.'
As to exogamy, Dr. Westermarck explains it by 'an instinct' against marriage of near kin.
Our study of psychoneurotic disturbances points to a more comprehensive explanation, which includes that of Westermarck.
For some of the main historic facts on intellectual disability, see Westermarck, pp. 264-277.
In this connection we may note an observation of Westermarck's during his residence among the country people of Morocco.