Viking ----> Cod ----> Existence
Poles are very hostile to human life especially in older times when there were no comforts. Winters are longer and colder but also they are dark at poles.
As humans migrated across Europe, a strange illness emerged especially affected the children. They were born with soft and deformed bones. Some died, but those who survived had to live with the deformed bones. This condition become known as RICKETS in children and OSIEOMALACIA in adults. Doctors were powerless to cure the disease as no one knew what was the cause behind it.
Scientific evidence came into light only in 1320 during an experiment in Vienna. It was discovered that children with rickets recovered miraculously after they were regularly allowed to play outside. Scientists realized without fully understanding that the sunlight is behind the cure.
7-Dehyrocholestrol in Sunlight(UV) -------> Pre-Vitamin D3 --------> Vitamin D#
This vitamin D3 is essential for absorbing calcium ions in your kidney and calcium is important for good bones.
Above 42 degrees latitude, there isn't enough sun in winters to form this vitamin D3, hence the epidemic rickets.
The only exception to these effects were the Vikings that occupied Norway, Denmark, and Sweden, where the sunlight is scarce (UV index is very low). Yet they were the fighting force, hence no chances of rickets in them. Vikings reached Iceland, Greenland, and even North America.
Scandinavia Cursed by low Sunlight but the cure to rickets was swimming offshores -----> COD.
Cod is a great source of vitamin D. their oily flesh and particularly in their liver. 1 meal of cod with its liver can give you enough Vit.D that can last you a month. One practice that has been passed down from generation to generation is extracting oil from the cod liver was a boom for the Viking civilization. Some People noticed that Cod liver oil drinkers are healthier or their children taller and sturdier than those people who lived inland. So the cultural practice of drinking cod liver oil spread. Humans living together observing one another and emulating works is the Proto Science.
Vikings understood that cod oil is beneficial but not exactly how beneficial or why? That's why Greenland Vikings died as they didn't continue the cod liver oil drinking practices.
The knowledge of the British That citrus fruits cure survey was one of the important factors why their fleet could withstand long voyages and hence occupied 32% of total land while Vikings failed.
Thanks, Full of good feeling...