eyes colour

" skin colour
"Yellow eyes

What does eye color depend on?

The base color of the eyes should be blue because the light rays, when they hit the eye, are diffused in an inversely proportional way to their wavelength. "wave, have a" high diffusibility, the eye has all the shades of blue as its base color.

Variable quantities of melanin, the same pigment responsible for the color of the skin, may be present at the level of the iris. Depending on the quantity of melanin produced, the eye takes on a rather broad spectrum of shades, ranging from blue to black. the quantity of melanin is scarce or nil the eyes are blue, while in the opposite case the iris assumes a brown color. When there is a different quantity of melanin inside the iris of the two eyes, the case of heterochromia can occur.

Why do all babies have blue eyes?

In the first months of life at the level of the iris the production of melanin is inhibited. The pigmentation process in fact takes a few months to fully activate (it becomes appreciable around the sixth-seventh month of life). The extent to which the ocular melanocytes will begin to producing melanin is dependent on the genetic heritage of the child and determines the color of the eyes. In dark-skinned children (black and Latin populations), for example, this phenomenon does not exist and the color of the eyes, already dark at the time of birth, does not varies with growth.

The blue color of the eyes is a recessive trait, while the brown is dominant. This means that the baby will have blue eyes as an adult only when the gene for this feature is present on both homologous chromosomes. In other words, two brown-eyed parents have very little chance of giving birth to a child with blue eyes (see figure), despite the fact that in the first months of life this is quite common.

In the figure, the concept is simplified for educational purposes, in reality the color of the eyes is determined by different genes, which account for the different shades present in nature (blue, gray-green, green, light brown, black etc.).

CONTINUE: Skin discolouration "