Infectious disease has shaped human evolution for millennia. During epidemics/pandemics, susceptible individuals with unfavorable genetics succumb to disease prior to reproducing while individuals with genetics that favor survival pass on their genes to subsequent generations. The current Covid-19 pandemic is the most recent of these events. Pre-vaccine, Covid-19 had a death rate of 1-2% for younger people of child-bearing age, and a death rate of up to 20% for older individuals and people with comorbidities. But previous pandemics – such as the infamous Black Death in the 1300s – were much more lethal and therefore these earlier pandemics shaped human evolution to a greater degree.
These researchers from U. Chicago compared DNA samples from people alive before and after the Black Death, and discovered genetic elements that contributed to surviving this plague. Descendants of these survivors have more potent immune systems, but they also suffer from an increased incidence of autoimmune diseases – a broad class of diseases that is caused by an overactive immune system. How will the Covid-19 pandemic shape human evolution in the coming generations?