science photo

10

Stunning portraits show not all redheads are white 

There’s a lot of mythology surrounding redheaded people, but one ignorant assumption trumps them all: Redheads are white. The reality? They’re not. Photographer Michelle Marshall is raising awareness of this fact through her photo series “MC1R.” Even someone with two black parents can have red hair.

That’s an Eye of a Different Color

Originally posted by sofothings

Originally, everyone had brown eyes, but Danish researchers say that somewhere between 6 and 10,000 years ago, a random genetic mutation tweaked a key molecular switch and the ability to produce brown eyes in some people.

Eye color is dictated, at least in part, by the OCA2 gene, which codes for the P protein involved in the production of melanin, the pigment that gives color to hair, eyes and skin. The actual mutation occurred in a gene next OCA2, which didn’t fully turn off OCA2, but did reduce its ability to promote melanin production.

Eye color — at least for the three most common colors: green, brown and blue — is governed by eight genes. The origins of other colors like gray and hazel are less well understood. Color variation is due to the amount of melanin in the stroma of the iris. Blue eyes have less.

Most babies are born with blue eyes that darken in the first three years as melanin, which isn’t usually present at birth, develops with age.

Heritability of eye color isn’t as simple as you might think. The color of your eyes is not a blend of your parents’ colors, but rather the plucking of chromosomal combinations. Parents with brown eyes are likely to have brown-eyed children, but not always. Darker colors dominate: Brown over green, green over blue.