During the 15th century when the Americas became inhabited by European settlers, indigenous peoples were exposed to diseases new to their body systems, leading to death in masses of native Americans whose bodies could not defend themselves. Recent findings have informed us that those infectious diseases that once threatened their entire population have since “molded the immunes systems of today’s indigenous Americans, down to a genetic level” (Genetic Mark 1). Using whole exome sequencing, researchers were able to compare immune-related genes from skeletal remains of indigenous people living between 500 and 6000 years ago to DNA samples from indigenous people living today, both samples deriving from the Tsimshian group. The estimated genetic shift took place around 175 years ago, when variants less likely to fight off illnesses such as smallpox became less apparent in DNA samples. As the disease landscape became altered by the presence of more aggressive diseases, the genetic variants in indigenous people became adapted and more capable of defending against illnesses.