I propose to make first a very brief critical survey of some of the most notable attempts that have been made to account for racial qualities, and I shall try to supplement and harmonise these as far as possible. We may with advantage consider at the outset the race-making period, and afterwards go on to consider changes of racial qualities in the historic period. This Part of the book is necessarily somewhat speculative, but its interest and importance for our main topic may justify its inclusion. CHAPTER XV THE RACE-MAKING PERIOD Let us now see what can be said about the process of racial differentiation which, as we saw in the foregoing chapter, was in its main features accomplished in the prehistoric or race-making period. We cannot hope to reach many positive conclusions, but rather merely to discuss certain possibilities and probabilities in regard to the main factors of the differentiation of racial mental types. I would point out at once that the answer to be given to the question—Are acquired qualities transmitted? Are the effects of use inherited? is all important for our topic. I do not propose to discuss that difficult question now. I will merely say that the present state of biological science makes it seem doubtful whether such inheritance takes place, and that, although the question remains open, we are not justified in assuming an affirmative answer; that, therefore, we must not be satisfied with any explanation of racial and national characteristics based upon this assumption; and in the following discussion I shall provisionally assume the truth of the Neo-Darwinian principle that acquired modifications are not transmitted. Assuming, as we must, that all peoples are descended from some one original stock, the problem is—Can anything be said of the conditions which have determined the differentiation of races of different mental constitutions, of the development of racial qualities which, having become relatively fixed, have led to the evolution of different types of national organisation and culture? And especially we have to consider the conditions which have produced, and may still produce in the future, the qualities that make for the progress of nations. We must suppose a certain social organisation to have obtained among that primitive human stock from which all races have been evolved, probably an organisation in small groups based on the family under the rule and leadership of a patriarch. It is possible that considerable divergences of social organisation may have taken place, without any advance towards civilisation; such divergences of social organisation must have tended to divert the course of mental evolution along various lines; but they must themselves have had their causes; they cannot in themselves be the ultimate causes of divergence of racial mental types.