Here, it may be remarked in passing, we seem to see the first faint expression of the father’s interest in the family, which, if I may hazard a guess, may have started in this way as a means of gaining his desire with the female. The correctness of this surmise will receive considerable confirmation as we proceed with our inquiry. And if analogies with animal conduct were not so apt to be misleading, I would venture to suggest the persistence of the same egoistic factor among many human fathers. But for the present I must leave this question. From the very beginning of life parental sacrifice is more common in the mother; it is in exceptional cases that her devotion is shared by the father. But such good fathers are of special importance to our inquiry. Even more interesting are those species among which the father takes all charge of the young, while the mother spends her time away from the family. Nor is this departure from what we may call the normal order of the family so surprising as at first sight it may seem, if we can account for the necessity under which probably it arose and seek to explain it. The welfare of the young is a matter of vital urgency; instinct dictates to the animals what reason dictates to us. Nature, as if to show her resourcefulness, her love of successful experiments, is always discovering contrary ways of attaining the same end. And what I wish to make clear is this: when, for some reason that we do not know, the family cares are neglected by the mothers, the work of tending and feeding the young is undertaken by the fathers. I shall have much more to say on this question at a later stage, and I ask you to keep it persistently in the focus of your attention. I desire to emphasise it at once. Whatever groups of animals we survey, we shall find examples of this replacement of the mother by the father, new aspects of the family, which may afford us a better grip of some problems that at present elude us.