But in that case, if struggle for extermination of rivals between men is the law of life, mankind is setting at naught the natural law, and must be on the way to extinction. Happily the natural law in this matter has been misread. The individual in his sociological aspect is not the complete organism. He who attempts to live without association with his fellows dies. Nor is the nation the complete organism. If Britain attempted to live without co-operation with other nations, half the population would starve. The completer the co-operation the greater the vitality; the more imperfect the co-operation the less the vitality. Now, a body, the various parts of which are so interdependent that without co-ordination vitality is reduced or death ensures, must be regarded, in so far as the functions in question are concerned, not as a collection of rival organisms, but as one. This is in accord with what we know of the character of living organisms in their conflict with environment. The higher the organism, the greater the elaboration and interdependence of its part, the greater the need for co-ordination.[53] If we take this as the reading of the biological law, the whole thing becomes plain; man's irresistible drift away from conflict and towards co-operation is but the completer adaptation of the organism (man) to its environment (the planet, wild nature), resulting in a more intense vitality. The psychological development involved in man's struggle along these lines may best be stated by an outline sketch of the character of his advance. When I kill my prisoner (cannibalism was a very common characteristic of early man), it is in "human nature" to keep him for my own larder without sharing him. It is the extreme form of the use of force, the extreme form of human individualism. But putrefaction sets in before I can consume him (it is as well to recall these real difficulties of the early man, because, of course, "human nature does not change"), and I am left without food.