The global population continues to grow, making less land and water available per person. But the unevenness of birth rates creates different challenges in different parts of the world. Today women in industrial countries give birth to one or two children on average, while those in developing countries have more than three -- and in 15 African countries the rate is over six.
Roughly 90 percent of people native to North America died in the first 100 years after Columbus discovered the New World, notes an environmental think tank as many gear up to celebrate the holiday Columbus Day.