Why blue eyes

He says blue eyes have been linked to people coping better with seasonal affective disorder, a major depressive illness that occurs when there are long periods of low light. Notably, he says, the eye has special neurones in the retina that can detect blue light and use this to help regulate circadian rhythms. Contrary to what we might have once learned in school, it is possible for two blue-eyed parents to have a brown-eyed child, says Sturm.

First there are genes that control the amount of melanin pigment in our irises — that's the part of our anatomy that acts like an aperture on a camera to control the amount of light that gets into the eye. Around 74 per cent of our eye colour can be put down to a gene called OCA2 on chromosome This gene also contributes to hair and skin colour, but to a much lesser extent. A variation in the HERC2 gene, which sits right next to the OCA2 gene controls whether melanin is produced in the outer layer of the iris.

If you turn the switch on the eyes will be brown. If you turn it off they become blue," he says. Then there are genes that control the structure of the iris, such as it thickness and how much collagen it contains.

Tags: eyes , evolution , anatomy. Email ABC Science. Use this form to email 'Why did humans evolve blue eyes? By clicking 'Send to a friend' you agree ABC Online is not responsible for the content contained in your email message. Skip to navigation Skip to content. UV light can pass through clouds and reflect off surfaces like car windows and pavement. The most protective sunglasses are wraparound sunglasses that protect the eyes from every angle.

You can also opt for photochromic lenses, which offer total UV protection but only become tinted when exposed to outdoor sunlight, and turn clear when you come indoors again. Your optometrist can help you choose the best lens and frame options for your needs and lifestyle. How We Can Help Whether you have blue eyes or not, sunglasses are an important part of keeping your eyes healthy for a lifetime.

Search: Search. Schedule An Appointment. Submit Your Resume. The color of our eyes depends on how much melanin is present in the iris. Brown eyes have the highest amount of melanin in the iris, and blue eyes have the least.

Brown melanin is the only pigment that exists in the eye; there is no pigment for hazel or green — or blue. Eyes only appear to be these colors because of the way light strikes the layers of the iris and reflects back toward the viewer.

At one time, it was believed that eye color, blue eyes included, was a simple genetic trait. Common knowledge said that you could predict a child's eye color if you knew the color of their parents' eyes, and possibly the color of their grandparents' eyes.

Geneticists now know that as many as 16 different genes influence eye color to some degree — far from the one or two genes that were once believed to determine iris hue. In addition to genetics, the anatomic structure of the iris can also affect eye color to some degree. In other words, it's impossible to know for sure if your children will have blue eyes — or any other color. Both parents may have icy blue eyes, but that's no guarantee their child's eyes will even be blue at all.

Human eyes don't have their full amount of melanin pigment at birth. This is why many babies are born with blue eyes, only to have their eye color change as their irises develop more melanin throughout early childhood. So don't be concerned if your child begins to lose their baby-blue eye color.