Incidental genocide

Little bugs inside our cells called mitochondria, carry genetic information all o  their own.    These mitochondria split, asexually, making kids .  So, scientists can look at changes in dead mitochondria  inside the bone cells of dead native Americans.  Thus they can track their migration paths, better, and they did this in the study below.

From the abstract: The data suggest that a small population entered the Americas via a coastal route around 16.0 ka, following previous isolation in eastern Beringia for ~2.4 to 9 thousand years after separation from eastern Siberian populations. Following a rapid movement throughout the Americas, limited gene flow in South America resulted in a marked phylogeographic structure of populations, which persisted through time. All of the ancient mitochondrial lineages detected in this study were absent from modern data sets, suggesting a high extinction rate. To investigate this further, we applied a novel principal components multiple logistic regression test to Bayesian serial coalescent simulations. The analysis supported a scenario in which European colonization caused a substantial loss of pre-Columbian lineages.

The part in bold, that is Europeans delivering virulent disease to native Americans.