DNA what did scientist learn about Black Death

Yersinia pestis.

Explanation:

The scientist learn from the Black Death that the death occur in black death is due to the bacterium named Yersinia pestis who is responsible for the outbreak of epidemics. By identifying the cause of black death, the scientists are able to produce antibiotics against this disease. The scientist takes the teeth of a dead person who died from Black death, test their DNA and find out that Yersinia pestis is responsible for this plague.