Like most human traits, blue eyes are determined by genes, and no two people have exactly the same hue. It works a lot like ...

Then you have something in common with most people around ... near-black—but scientists believe that they’re all slightly different manifestations of blue eyes or brown eyes.

Researchers pin this genetic mutation to the area around the northwest of the Black Sea ... from fair Scandinavians to dark-skinned, blue-eyed people in countries like Turkey and Jordan.

Thus, it's possible that blue-eyed people ended up having more of a competitive edge in this geographical area as blue eyes were rarer. As they explain in the paper, “The rare-colour advantage ...