When a mysterious flesh-rotting disease broke out in Europe in 1495, two years after Christopher Columbus returned from the Americas, suspicion fell on his crew.

A new study published in the journal Nature provides compelling evidence that syphilis originated in the Americas and spread globally through European colonization.

Paleogenomics has finally solved a question that has puzzled researchers for decades: Where did syphilis come from?

The implications of this research are manifold. The study paints a grim picture of colonialism’s unintended consequences. While European explorers brought smallpox, measles, and other deadly diseases to the Americas, syphilis may have been the New World’s equally devastating gift in return.

In the spring of 1495, the Italian campaign of Charles VIII of France was interrupted by an intense outbreak of an unknown disease that caused extremely high mortality rates and quickly spread throughout Europe,