With much fanfare, estimates of the earth’s population recently surpassed 7 billion people. Population growth rates have been staggering for decades, for a number of reasons. The straightforward explanation is that global birth rates have remained high while there has been tremendous improvement in child mortality rates and life expectancy. Sewer system implementation in the 1800s helped separate waste from drinking water and cut down on the spread of cholera and typhus. Later medical advances in the form of a smallpox vaccine and Penicillin, coupled with DDT control for Malaria, helped more people live longer. As people lived longer, more reached childbearing age and had children themselves. Back in the 18th century, replacement fertility was up to six children. In order to keep population stable, women needed to have...
