The latter half of the twentieth century saw two really weird and counterintuitive trend lines in developed countries. While dangerous infectious diseases like smallpox, mumps, measles, and tuberculosis were successfully pushed back and in some cases got to the verge of elimination, other diseases and disorders began to grow or even skyrocketed. The rates of diseases like multiple sclerosis, hay fever, Crohn’s disease, type 1 diabetes, and asthma have increased by as much as 300% in the last century.
