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Archaeologists excavating Viking latrines have found that genes adapted to fight internal parasites could be harmful for their modern day descendants.

Vikings have always had a pretty notorious reputation, but new research suggests that they may have left behind another troubling legacy.

Being a Viking wasn’t ALL fun and games

Recent excavations at Viking latrine pits in Denmark have found that despite being strong and fearsome warriors, the Vikings suffered terribly from internal worm infestations.

In order to combat this, studies into the Vikings’ DNA have found that their genes actually adapted to become better at protecting their bodies from these parasites, and it’s a trait that can still be found in their descendants today.

New research led by the Liverpool School of Tropical Medicine has concluded that this same gene could now be causing some serious problems for those who inherited it, particularly emphysema.

The science

Our bodies naturally produce enzymes which are capable of breaking down our own organ tissues. To prevent this, our bodies also produce inhibitors, which protect the organs from damage by these enzymes.

Medical research into why some people have a more natural risk of developing lung disease has discovered that the only inherited risk factor appears to be a deviant form of one of these inhibitors – alpha-1-antitrypsin (A1AT).

As it turns out, this mutation is really effective at inhibiting the type of protein-digesting enzymes produced by parasites, but is consequently much less able to deal with the body’s own naturally occurring ones. The gene variant is particularly common in Scandinavia, and can be traced back to Viking DNA, when it appears to have initially evolved to protect the Vikings from their high exposure to parasitic diseases.

Fast forward to today…

Our modern medicine now allows us to effectively tackle internal worms, meaning the deviant gene is now more or less obsolete. For people who still carry it, however, the mutant form of A1AT is instead potentially increasing their risk of lung disease.

Since life expectancy was nowhere near as long for the Vikings as it is for us today, the Vikings didn’t live long enough for the deviant gene to cause a problem. But with our ever increasing life span, the body’s decreased ability to manage its own enzymes is having a serious impact on the respiratory health for carriers of this gene variant.

This lasting legacy from the Vikings shows us not only how much our bodies can be shaped by our environment, but also gives an insight into the living conditions in Viking settlements. The levels of exposure to parasitic disease, and the types of parasites present, can tell us about what diseases people suffered from, which domestic animals they kept, and how close to each other they lived.