Populations that live in more northern areas show a mutation in DNA that codes for TRPM 8, a protein that responds to cold sensations. A recent study has uncovered that people with this mutation have a notably higher risk of developing migraines. The mutation is obviously seen more in populations with colder climates, 88% of the population in Finland have it while only 5% of those from Nigeria do. Scientists still aren't quite sure how the mutation works or why it was developed but they do believe it may have conferred some sort of early benefit and the increased risk of migraines just happens to be a side effect of the mutation.
This article is interesting me because it shows that current Genetics is still guess work in some areas. Sure a mutation can be identified by sampling the population but determining exactly what it does or why it came about in the first place is like solving a puzzle if it is not blatantly obvious. Like TRPM 8 from the article, there is a clear environment where it is more prevalent in and it must have survived for centuries and have been important for some reason to be in such a large portion of the population but scientist still aren't sure exactly what that reason is.
Article - https://www.sciencenews.org/article/adapting-life-north-may-have-been-real-headache?mode=topic&context=88&tgt=nr
Journal - http://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1007298