Human Eye Color
Eyes are sense organs that react to pressure and light to create vision. They attain their color from melanin variations that occur in the iris. Common human eye color includes blue, hazel, brown, gray and green. The human eye color is determined by the blending of white collagen fibers with the melanin present in the eye’s iris. Low melanin results in blue eyes while adequate melanin results in brown eyes.
The Eye’s Iris Pattern
Iris is the circular part of the eye that controls the pupil’s size and diameter. The iris’s color is referred to as the eye’s color. Its color exists in different shades and patterns that range from light blue to dark brown. Green and gray are the least common eye colors. Apart from different colors the iris’s fibrous tissue forms unique patterns per individual that are used for biometric identification just like finger prints.
Genes That Determine Eye Color
The human eye color is determined by a number of genes like HERC2 and OCA2. Human chromosome 15 contains these two genes that are responsible for melanin production. OCA2 produces P-protein used in melanin synthesis. HERC2 is responsible for regulating OCA2’s action by making it active or inactive as the body requires. A single nucleotide polymorphism present in HERC2 determines the human eye color that ranges from blue to brown.
Inheritance Of Human Eye Color
According to scientists, two genes; EYCL1 and EYCL3 are responsible for eye color inheritance. EYCL1 is also called gey gene and contains blue and green alleles while EYCL3 is called bey2 gene and contains blue and brown alleles. Brown is dominant over blue and green alleles. Therefore, if a person has one blue allele or one green allele and a brown allele, they have brown eyes. Green is dominant over blue and a person gets blue eyes when all alleles.