In 1788 Thomas Malthus published the "Malthusian Theory," which says that human population will increase up to the limit of the food supply, with wars, disease and starvation being the main factors of control. Increased agricultural production tends to postpone the time at which population catches up to food supply while modern medicine tends to hasten the process. Some religious groups and social movements also influence population to some extent.
Since human population doubles every 40 years, we are in need of a solution to overpopulation. California might again demonstrate leadership by enforcing two progressive policies: Same-sex marriages only and, for out-of-wedlock parents, the rule, "If you can't feed 'em, don't breed 'em."