Before the beginnings of agriculture and industrialism, human population remained relatively stable or grew slowly and steadily. From 0 A.D. to 1000 A.D., population remained essentially unchanged, at around 300 million. Yet after certain technological advances that have allowed humans to more readily exploit natural resources, the population has undergone explosive growth. The world population doubled from 1800-1930 (from 1 billion to 2) and then again by 1975. Today, total population is about 6.6 billion and the UN predicts it to grow to over 9 billion by 2050.