Completely uneducated guess: Dark skin is an adjustment for areas that take on more sunlight, and even migrating a little north can mean that you are not gettin

Completely uneducated guess: Dark skin is an adjustment for areas that take on more sunlight, and even migrating a little north can mean that you are not getting enough sunlight (oh you already mentioned this but I missed it or was added later, anyway...) For people who have light skin and still have deficiency: Office life probably means you must be proactively chasing sun in your free time, or get the damn supplements and be done with it :)