Man's bad habits have kept pace with his progress
This spreading of habits or customs took place very rapidly among men and was the source of the various changes which distinguished civilized life from savage life. But we must here point out that not only good habits were so spread, but bad ones as well. The origin and the use of opium and of alcohol, the injuries of fashionable dress and the economic wrongs of tyrannical government originated along with the birth of language, art, science, and all that uplifts and benefits mankind.
Clearly, then, that man is misinformed who defends a wrong by referring to its age and reasons that, if certain things were harmful, they would not have survived. To the young thinker the existence of harmful ideas and habits among mankind may at first seem inconsistent with the principles of the survival of the fittest, but this difficulty will disappear upon further investigation.
Factors that determine the survival of races
Since the beginning of recorded history many factors have helped to determine what kind of individuals and races should survive. War, economic wealth and poverty, intellectual beliefs, religions, and social institutions have all been potent factors in determining who should survive. With wealth and conquest came the opportunity to gratify tastes and passions of which the poor individuals of weaker races could not avail themselves.
Many habits and customs detrimental to life and health
Many of the habits and customs which man has developed are not necessary to life, and may be positively detrimental to health and longevity. They have been handed down from generation to generation, not because of their benefit to man, but in spite of their detriment.
Such condition of affairs would not be possible if man were not the dominant animal. Man's intellectual supremacy has given him power over the rest of nature, which has resulted in making his struggle for existence much less severe. His use of weapons and of artificial protection from natural destructive forces, as severe heat or cold, has made it possible for him to live and to produce offspring in spite of wrong habits and wrong methods of living, and the natural resistance of life.
Man's organs have a limited power of adaptation