The article was not fully comprehensive. It may be a segway Into future research. If this line of research continues they will likely look more closely at the different colors and their response to different environmental conditions. While there are people with all different colors of eyes all over the planet and population groups with light eyes at different latitudes and vice versa their are higher numbers with specific colors in certain regions. Eye color is typically not exclusive to one area but may be more common. For example you find blue, green, honey colored....etc eyes in Africa and brown eyes in Europe.