EARTH IS NOW HOME to nearly 6 billion people, and the population is still growing rapidly.Since roughly 1 billion of those people are girls under the age of fifteen, most of whom will want children, it is inevitable that the human family will continue to expand for some decades, reaching 7 billion soon after the year 2010, 8 billion by 2025, and perhaps 9.5 billion by 2050.This is certainly a critical trend, one that will shape a more crowded future.