Prior to the Demographic Transition, fertility in northwestern Europe was controlled by limiting marriage. Marriage was regulated by landowners and the churches, and was not allowed unless a man had accumulated the resources necessary to support a family. Long periods of being landless, a servant, or an apprentice, precluded marriage. Once married, there was no control of fertility. But, only about half of adults were married at any given time, so fertility was about half of what it might have been. Eventually, contraception was accepted and fertility within marriage fell. Society no longer needed to control marriage so tightly and marriage rates rose dramatically. The options of marriage, sex and childbearing passed from community control to individual control. The fertility decline occurred very rapidly in Europe, mostly between 1870 and 1930. It has been difficult to prove a socioeconomic basis for the decline. The largest study, The Princeton European Fertility Project, argued that cultural transmission of new social norms was crucial. The Demographic Transition encompassed a ten-fold increase in population, a three-fold increase in life expectancy. It drastically changed the human experience of life.