Although bubonic plague and a variety of other infectious diseases continue to afflict humans, modern medicine and public health practices have done much to lessen mortality. Those practices, combined with changes in food production, have lead to a Malthusian explosion of the human population, which now exceeds six billion. Arguably, most people in the world would not be alive today without the benefit of these modern advances. They or their recent ancestors (parents, grandparents, etc.) would have died in their pre-reproductive years. That doesn’t mean humans should be extinct. Rather, it means that a different set and a much smaller number of individuals would be alive today. It is estimated that today's United States population would be 37 to 50 percent smaller, if the mortality rates of 1900 continued through the twentieth century.

For group discussion:

• Provide examples of your family’s encounters with infectious diseases such as polio, tuberculosis, measles, scarlet fever, influenza, etc.
• Does the fact that most diseases are controlled mean that human evolution has stopped? Does it mean that the human gene pool is being degraded? Is modern medicine with its miracle drugs subverting the survival of the fittest?