I live in Poland and I spent my young years on a farm. In the winter you barely see any sunlight. There is nothing to do outside but plenty to do inside as you take care for the animals and do other stuff that you don't have time for in the summer.
I assume this has been the same for pretty much everybody in Europe for thousands of years except for the last couple of decades.
The link I posted is the data you are looking for. In particular it days that the DPSD mutation is more common in Africans than in Finnish people, and more common in South Asians than Europeans. The lengths of days and nights seems to have nothing to do with the prevalence of the mutation.
So these “evolutionary adaptation” explanations are a) not supported by the data and b) unnecessary to begin with!
I live in Poland and I spent my young years on a farm. In the winter you barely see any sunlight. There is nothing to do outside but plenty to do inside as you take care for the animals and do other stuff that you don't have time for in the summer.
I assume this has been the same for pretty much everybody in Europe for thousands of years except for the last couple of decades.