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My Ancestors Survived the Bubonic Plague, And All I Got Was This Lousy Autoimmune Disease
How natural selection left so many of us with incurable diseases
In 1347, Pope Clement VI sat on his throne in the great halls of his palace, encircled by the crackle and hiss of two towering bonfires. As the heat warmed his sleepless face, Clement prayed the fire would protect him from the plague ravaging Avignon.
Outside Clement’s fiery sanctuary, the once-thriving streets lay deserted, their bustling energy swallowed by an eerie stillness broken only by distant mournful moans. Inside homes, plague victims succumbed to slow and exquisite torture—fever, chills, fatigue, delirium, and the telltale buboes—painful, black, swollen lymph nodes that signaled the body’s defeat against the unseen foe. It was called the bubonic plague, and it got that name from the buboes that swelled lymph nodes on armpits and groins.
As the plague swept across Europe, in Avignon, bodies piled up like cordwood into freshly dug pits. The death toll mounted so quickly that gravediggers could not dig graves fast enough. According to one chronicler, “The stench from the mass graves was so appalling that people could hardly bear to go past a churchyard.” Eventually, Clement consecrated the entire Rhône River so that bodies could be thrown into it and given a proper Christian burial.
Doctors attended the sick in long robes and beaked masks stuffed with flowers, believing their potpourri of floral scents would protect them from the “miasma” — the foul smells that spread the plague.
Many believed the plague was God’s wrath, while others blamed foreigners (mostly Jews) or anyone with the wrong religion. But while people fretted and pointed fingers at illogical scapegoats, the real culprit was a microscopic tormentor, Yersinia pestis (Y. pestis) — the plague bacterium that lived inside the gut of fleas.
Fleas were perfect disease vectors. They stealthily traveled on rodents, cats, dogs, and humans, eventually biting their hosts and infecting them. Between 1347 and 1351, as much as 30–60% of the population died from the bubonic plague.
However, a victor stood tall in this grotesque tableau. The other half of the…
