Growing up, children have been taught that the Black Death, which spread throughout London in the mid-1300s and killed roughly 60 percent of the population, was caused by fleas off the backs of rats traveling on boats from Asia.

However, researchers believe the disease, previously thought to be bubonic and spread through fleabites from human to human, was actually an airborne virus given its fast-spreading nature, according to the Washington Post. Such a pattern of transmission would make the black death a pneumonic plague, not a bubonic one.

The team of London scientists developed the new theory after examining the teeth of the 25 skeletal remains that had been infected with the disease. The researchers found traces of the Black Death bacterium, Yersinia pestis, in the remaining DNA.

Researchers found that the strain of virus in the skeleton's teeth was the exact match of the disease that killed 60 people in Madagascar last year.

London Crossrail unearthed the skeletons at Charterhouse Square in March 2013 during excavations for a new rail line, International Business Times reported. Charterhouse Square is believed to have been the emergency burial site for tens of thousands of Black Death victims.

Crossrail Lead Archaeologist Jay Carver told  the discovery of the skeletons would be able to shed light on the more than 600-year-old mystery.

"This discovery is a hugely important step forward in documenting and understanding Europe's most devastating pandemic," Carver said. "What's really exciting is the brining together many different lines of evidence to create a picture of such a devastating world event as the Black Death."

The Guardian reported that the Public Health England's Dr. Tim Brooks said that for a virus to have spread that quickly like the Black Death did, it had to have been airborne and caught from other humans coughing and sneezing.

"As an explanation [rat fleas] for the Black Death in its own right, it simply isn't good enough," Brooks said. "It cannot spread fast enough from one household to the next to cause the huge number of cases that we saw during the Black Death epidemics."

Through the skeletal remains, researchers additionally found that many Londoners and Europeans living during the 14th and 15th centuries were often times malnourished or overworked. The poor health conditions of Europeans living in that time could explain how they were infected so easily.