Global society has long held fears about overpopulation, the central topic of Chapter 2. Jahren provides a parade of past societies that feared they were getting too big. In Mesopotamia, a society that thrived around 1800 BCE, they feared there would not be enough resources to feed their communities. In Ancient Greece, Aristotle expressed the same anxiety. In 1798, Thomas Robert Malthus published An Essay on the Principle of Population, which “really took overpopulation neuroses to the next level” (11). In the mid-19th century, John Stuart Mill also feared a lack of food for a growing population.

Historically, these concerns have often been unfounded. In the 21st century, however, what was once a fear is now more of a reality. There are currently seven billion people living on Earth. The women who are most likely to have a large number of babies are those living in countries or societies with extreme gender inequality, including low female wages and limited access to healthcare and other opportunities—these are what Jahren calls “high gap” countries (12). Jahren supports efforts to curb global population growth through the education of women: “It makes sense that the most effective and long-lasting mechanism for curbing global population growth revolves around an elimination of gender inequality” (13).