Dunn writes that many human ills and behaviors reflect the evolutionary past where we put ourselves above nature and all other species. Our super sterile environment is hurting us all by unbalancing our immune systems, leading to attacks on our own tissues rather than invading organisms. His solution is to repopulate the gut with worms that the immune system tolerates or that may suppress the system’s hyperactivity. Dunn writes that Crohn’s and other such disorders are rare wherever gut parasites are common. There is actually a cottage industry selling worm eggs. Some people have even travelled to go barefoot in a primitive latrine in hopes that worms will infect them to cure their autoimmune disorders. Other subjects he tackles is why some peoples can digest milk but the majority of the world cannot. What the appendix does and why is appendicitis rare in third world countries. How bugs lefts us hairless. Many interesting ideas are raised and discussed. Some parts of the book needs skimming but it’s still worth the read.