Thus, for as long as humans bred, the supply was inexhaustible. Yet, this view of human resources is fast becoming extinct in the rich Western countries. Training periods have lengthened, expert knowledge has taken over, the main value added is information. Humans represent a sizeable investment in education. They are no longer an inexpensive resource .With this realization, there came about a revolution in economic relations.
All resources are scarce.
The concept of opportunity cost is the first that students of economy encounter. The classic approach included natural endowments in the group of scarce resources. The human element was barely perceived as yet another natural resource. Now it is. The size of the population, its life expectancy, its quality of life, health, education, income are all important.