(1) The first, the least speculative, evolutionary criterion of an animal is its degree of adaptation to its environment.
(2) Man exhibits a less degree of adaptation to environment than any other animal; principally because (a) he consists, roughly speaking, incomparably more than any other animal, of three interdependent parts—body, thinking brain, and that higher mental function that we call spirit—the development of any one of which, beyond a certain stage, is found to be detrimental to the other two; and because (b) he is able possibly to control directly his own evolution, and certainly to modify it indirectly by modifying the environment in which he evolves. He is able to make mistakes in his own evolution.
(3) The typical poor man is better adapted to his environment, such as it is, than the typical man of any other class; for he has been kept in closer contact with the primary realities—birth, death, risk, starvation;—in closer contact, that is to say, with those sections of human environment which are not of human making and which are common to all classes. He has fewer mistakes to go back upon.
It might be said, of course, that mal-adaptation at any given moment is more than counterbalanced by greater evolutional potentialities, or by greater inducement to evolve; and that the above chain of reasoning simply goes to prove that the poor man is more of an animal—less evolved. On the other hand, from an evolutionary standpoint, the animal faculties are the most basic of all. A sound stomach is more necessary than a highly developed brain, and good reproductive faculties are essential; because the first demand of evolution is plenty of material. It does not follow that our typical poor man is more of an animal, is less evolved, or has a smaller potentiality to evolve, because he has preserved better the animal faculties which lie at the basis of evolution.
Furthermore:
(4) There is a reasonable probability that an interior balance, between body, brain, and spirit, is more needful for realising the potentialities of evolution than rapidity of development in any single respect. Mens sana in corpore sano—animaque integra is an ideal as sound as it is unachieved. More haste less speed, is probably true of human evolution. A healthy baby is more hopeful than a mad adult.
(5) The typical poor man does, now, exhibit a better balance between these three components of him. Less evolved in some ways, he is on the whole, and for that reason, more forward. His evolution is proceeding with greater solidity. It is more stable, and more likely to realise its potentialities.
That is a speculation among probabilities and possibilities; an attempt to go in a bee-line across fields that are mainly hidden ditches; a first spying out of a country that wants mapping; a course over a sea that can never perhaps be buoyed, where bearings must be taken afresh from the sun for each voyage that is made. In any case, my belief grows stronger that the poor have kept essentially what a schoolboy calls the better end of the stick; not because their circumstances are better—materially their lives are often terrible enough—but because they know better how to make the most of what material circumstances they have. If they could improve their material circumstances and continue making the most of them.... That is the problem.
Good Luck to us all!