For each keyword, write 1-2 sentences indicating how the keyword relates to the chapter story. In other words, tell me how the keyword is connected to the chapter story (or the relevance of the keyword to the chapter story). Do not provide a definition of the keyword.

  
 

Human populations grew slowly at first and then at a much faster rate in recent years. At least twice in the course of human history, global human population has hit a dramatic growth spurt. The first came around 10 000 years ago, when the Agricultural Revolution dramatically increased the amount of food we could grow, and thus the number of mouths we could feed. As more food translated into healthier people, lower death rates, and longer life spans, the growth rate increased and global population raced toward the 100 million mark. The next growth spurt came in the 1700s, when the Industrial Revolution ushered in a rapid succession of advances in both sanitation and health care-including vaccines, cleaner water, and better nutrition. Once again, death rates fell, life expectancy rose, and the population swelled. [infographic 4.1]