Socialists like to portray Malthusian thinking as being pessimistic and faulty. Yet, the rapid increase in global population after the discovery of coal and oil clearly shows that populations do increase after advances in technology and resource supply. The limitation of population growth in advanced societies is due mostly to educational aspirations of the females that attend university and have less time to reproduce then do third world country females. The acquisition of luxury consumer items may also limit and stymie the size of first world families. Thus, they spend more money and time on luxury items and less time and money on their offspring.