Did the high incidence of alpha 1 antitrypsin help the Vikings survive the fact that they carried a lot of parasites?
This can cause emphesema and liver disease.
Last year, Danish scientists studying the remains of a Viking privy found that the ancient Norse and their domestic animals were infested with a variety of intestinal parasites. These parasites release enzymes called proteases that cause disease. The immune system also creates proteases that can cause inflammation and damage, but the body has natural defenses against those, including a molecule called alpha-1-antitrypsin (A1AT).
Because they were more or less constantly infected, Vikings evolved to produce “deviant” forms of A1AT that were specifically useful against worm-related proteases instead of the body’s own.
In the absence of normal A1AT, the immune system’s own proteases are free to damage tissue, including in the lungs and liver. At the time, the benefits of this genetic mutation outweighed the risks. Not so today.
Science has an article about the lost Viking settlement in Greenland.
The story goes that they were farmers, but when the Little Ice Age came, they kept farming and slowly starved to death because they were just too rigid to learn to hunt seals etc from the local Inuit.
But now some question that since the prescence of seal bones in the garbage heaps suggest they did hunt a lot.
For later reading.