For three glorious days, major media outlets lost their collective minds while drenching every corner of the planet with the word "shithole" — a term the U.S. president may or may not have thrown out in the confines of a closed-door meeting. It was in reference to certain countries and whether or not the people living there are worthy of traveling outside country borders. 

But as experts have finally confirmed, some of the biggest shithole moments in history have come from Europeans — the most recent of which relates to the Black Death. For years, it's been understood that one of the worst pandemics in human history (accounting for an estimated 25 million deaths between 1347 and 1351) was spread by rats. Scientists from the University of Oslo and the University of Ferrara now disagree, however, and think human "ectoparasites" — such as body lice and human fleas — might be the more appropriate culprits to blame.

In the report published in the "Proceedings of the National Academy of Sciences," researchers modeled different outbreak scenarios to understand the patterns of how it was spread. They found that the fleas or ticks found on human clothes were the more believable culprit, as the plague spread too fast for rats to have anything to do with it. 

“It would be unlikely to spread as fast as it did if it was transmitted by rats,” says Nils Stenseth, professor at the University of Oslo and co-author of the study, to BBC News. “It would have to go through this extra loop of the rats, rather than being spread from person to person.”

As Newsweek reports:

"Researchers at the University of Oslo ran computerized mathematical simulations of disease spread by human-to-human fleas and lice, by human-to-rat-to-human fleas, and by airborne pathogens.

The researchers compared those computerized simulations to nine examples of the actual spread of the Black Death. They found that the simulations of human-to-human models most closely resembled the actual spread patterns in the nine real studies that they investigated, indicating that rats might not have been involved at all."

Surprisingly, it isn't such a new theory. Past studies have also suggested this scenario to be true and target the possibility of the spread being almost entirely humans' fault.

History confirms, shitholes unite.