But increase in size and activity, and the expense of producing each new individual, led to the adoption of placental development.  And the mammal is so complex, the road from the egg to the fully developed young is so long, that a long period of gestation is necessary.  And even at birth the brain, especially of man, is anything but complete.  Hence the necessity of the mammalian habit of suckling and caring for the young.  And this feebleness and dependence of the young had begun far below man to draw out maternal tenderness and affection.  And the mammalian mode of reproduction and care of young led to a more marked difference and interdependence between the sexes.

The result of this is man’s family life, as Mr. John Fiske has shown so beautifully in that fascinating monograph, “The Destiny of Man.”  And family life once introduced becomes the foundation and bulwark of all civilization, morality, and religion.  Far down in the mammalian series, before the development of the family, maternal education has become prominent, and the young begins life, benefited by the experiences of the parent.  How much more efficient is this in family life.  But, furthermore, the family is perhaps the first, certainly the most important, of those higher unities in which men are bound together.  Social life of a sort undoubtedly existed, before man, among birds, insects, and lower mammals.  The community was often defective or incomplete in unity, or existed under such limitations that it could not show its best results, but that it was of vast benefit from an even higher than mere physical standpoint, no one will, I think, deny.  But with the family a new era of education and social life began.

First of all, the struggle for existence is thereby greatly modified and mitigated.  This crowding out and trampling down of the weaker by the stronger is transferred, to a certain extent, from the individual to the family and, in great degree, from the family to larger and larger social units.  For within the limits of the family competition tends to be replaced by mutual helpfulness, and not only are the loneliness and horror of the struggle between isolated individuals banished, but, what is vastly more, the family becomes the school of unselfishness and love.  And what has thus become true of the single family, and groups of nearly related families, is slowly being realized in the larger units of communities and states.  For, as families and communities are just as really organisms as are the individual men and women, whose soundness depends upon the healthy activity of every organ, so there is a survival, first of families, then of communities and rival civilizations, in proportion to their unity and soundness in every part.  For on account of the close bonds of family and social life, and in connection with the development of articulate speech, a new kind of heredity, so to speak, arises, of vast importance for both good and evil.  This mental and moral heredity, over-leaping all boundaries