In "Blowback," author Brad Thor discusses the historical impacts of pandemics on genetic evolution. Alan highlights how the smallpox pandemics of the Middle Ages have inadvertently shaped human genetics, leaving a legacy that protects certain individuals against modern diseases. Unlike the plague, smallpox led to a unique genetic adaptation among descendants of northern Europeans.

This fascinating observation indicates that about one percent of these individuals possess a rare genetic mutation that renders them nearly immune to HIV, the virus responsible for AIDS. This connection underscores the long-lasting effects of past pandemics on contemporary health and genetic resistance.