It is believed that the earliest human ancestors came from the African continent. When primates adapt and branch into many different species on the tree of life, they eventually become the lineage of our modern humans. As the equator passes directly through the African continent, the country there receives almost direct sunlight throughout the year. This direct sunlight, ultraviolet light and warm temperatures put pressure on the natural selection of dark skin. Pigments, such as melanin in the skin, protect against these harmful sun rays. This allows individuals with darker skin to live longer, and they will multiply and pass on the genes of dark skin to their offspring. The major genes that control eye color are closely related to genes that cause skin color. It is believed that ancient human ancestors had dark brown or near-black eyes and very dark hair (this is also controlled by genes related to eye color and skin color). Although brown eyes are still considered to be the main overall eye color, it is now easy to see several different eye colors in the global population. Where are the colors of all these eyes coming from? Although evidence is still being collected, most scientists believe that the natural choice of lighter eye color is associated with a looser choice of darker skin tone. As human ancestors begin to migrate around the world, the pressure to choose darker skin is not as strong. Especially for the human ancestors who are now Western European countries, choosing black skin and dark circles is no longer necessary for survival. These high latitudes offer different seasons, with no direct sunlight near the equator of the African continent. Because the selection pressure is no longer so strong, the genes are more susceptible to mutation. When talking about genetics, the color of the eyes is a bit complicated. The color of the human eye is not determined by a single gene like many other features. Instead, it is considered a polygenic trait, which means that there are several different genes on various chromosomes that carry information about the color of the eye that the individual should have. These genes, when expressed, are then mixed together to form various shades of different colors. Easy selection of dark eye colors also allows for more mutations. This creates more alleles that can be combined in a gene pool to create different eye colors.