To answer the first question we cannot do better than argue back from what is now the most salient feature about man’s biological position, namely that his survival is determined far more by his relations to the social group to which he belongs than by personal efficiency: hence he can draw on the collective resources of his tribe, and, to a growing extent, gets emancipated from the control of natural selection. Thus social selection and the survival of societies profoundly modify (and often defeat), the working of natural selection. The advantages are obvious; it is no longer essential for a member of a society that collectively controls the conditions of existence to develop any high degree of personal capacity, in order to survive. A single wise and provident minister, like Joseph, is enough to keep alive millions of Pharaoh’s subjects through the lean years of famine. But the inferior and incompetent survive with the rest. Now, if we suppose that by mid-palæolithic times man had established his ascendency over nature and perfected his social organization sufficiently to render these services to his fellows, we have suggested a possible cause of the cessation of biological progress. For social influences are as likely as not to be ‘contra-selective,’ that is, to tend to preserve by preference the stocks which are less viable from a merely biological point of view. They are markedly so at present, and it would be asking too much to expect the tribal chiefs of early men to have been wise and provident enough to see to it that their social institutions were eugenical in their effects. We cannot even now find such a pitch of wisdom and providence in the controllers of our destinies. III The answer to the second question is much easier. The human race has continued to progress in its culture, in its knowledge, in its power over nature, because it has devised institutions which have created for it a continuous social memory that defies death. Now, as ever, the wisest and the best must die, while their place is taken by babies born as ignorant and void of knowledge as in the beginning. Only there has been invented apparatus which relieves the civilized baby of his hereditary ignorance, and renders him potentially the heir to all the wisdom of the ages. In the first place, _Language_ not only extends enormously the possibilities of co-operation and common action, but also renders possible the consolidation of customs and their preservation by oral tradition. In the next place, _Writing_ enables a society to record all that it considers worth remembering. Upon these two inventions may be reared vast intricate structures, religious, political, social, and scientific, which knit together and dominate human societies from generation to generation, and create the conditions for an almost mechanical accumulation of knowledge.