The Black Death was a pandemic, caused by the bacterium Yersinia pestis, that wreaked havoc on Europe from 1347 to 1351 A.D. During this period, King Edward III of England purchased a piece of land that he decided would be a cemetery for the victims. This burial ground, now containing over 700 people, is being used to investigate the influence that the Black Death had on human genomes.
The ERAP2 Gene and the Black Death
ERAP2 is a DNA sequence that is located on chromosome five. The gene codes for an enzyme that helps process foreign substances so they can be presented to the immune system. This function gives it influence over the triggering of immune responses, meaning that mutations in this sequence could either help or hurt the body’s ability to fight against foreign invaders.
Modern-day digs at the site of Edward III’s medieval cemetery revealed that, in the years following the Black Death, the percentage of skeletons with specific mutations at the location of the ERAP2 gene had changed. This caused scientists to believe that the mutation provided significant protection against infection during the period. This protection allowed more people with the mutation to survive and to have children that also had the mutation.
The Bad News
As the number of people with this mutation has increased due to the evolutionary pressure of the Black Death, scientists have been curious about other ways that it could impact health. They have found that it increases the risks of autoimmune diseases, such as Crohn’s disease. This is because it helps to improve the ability and strength of the immune system. However, the effects of ERAP2 are simply small portions of a larger story about the impact of past pandemics on modern genomes.
