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  • You might think your hair and eye color are permanent, but in reality, they could change

  • at ANY TIME. And it definitely already changed once.

  • Greetings programs, Trace here for DNews. Many babies are born with blue eyes, and then

  • their eyes change color as their genes continue to develop. Hair color is the same way, sometimes,

  • babies are born with very light colored hair which gradually darkens. We got a few questions

  • on this, so we did the digging!

  • The colored part of the eye is the iris, it controls how much light is let into the eyeball

  • and it's color is determined by melanin, just like skin and hair. Darker colors absorb more

  • light, and lighter colors reflect more.

  • Eye color is determined by a few different genetic factors, the most important being

  • OCA2. OCA2 produced melanocytes, or melanin producing cells. Melanin is the protein that

  • creates skin, eye, and hair color. More melanin means darker eyes, hair, or skin. The COLOR

  • of the melanin in the eyes is determined by three OTHER[a] genes, EYCL1, 2 and 3. Together,

  • they account for brown/green/blue but not hazel or grey eyes, science is still working

  • on how we get those. All blue-eyed people can trace their ancestry back to a single

  • human born between 6 and 10,000 years ago. Due to a genetic mutation, a human was born

  • with a tiny switch right before the OCA2 gene, that limits the expression of the melanin,

  • kind of like diluting the stream of the protein. Individuals with albinism or Albinos have

  • the OCA2 gene completely shut off -- so their skin, eyes, and hair have no melanin at all!

  • With this in mind, let's apply it to babies. When we're born, our genetics are decided,

  • but the body hasn't necessarily acted on all the genes in your DNA. When it comes to eye

  • color, the melanin controlled by the OCA2 gene is diluted and thus we all have blue

  • eyes. For those with that blue-eye gene mutation they eyes stay blue. But for the vast majority

  • of us, once we're born the OCA2 gene kicks into gear, creating melanocytes to make proteins

  • and the eyes turn a different color, somewhere between 9 months and two years after birth.

  • A medium amount of the melanin makes eyes green or hazel, a large amount makes them

  • brown.

  • With regard to hair, the melanin builds up the same as in eyes, creating a dark color.

  • As babies age, their melanin levels increase and their hair will darken. Hair colors can

  • change well into puberty, as some genes aren't "switched on" until the hormones flood the

  • body in adolescence. Eventually, usually in the 30s, human hair stops producing melanin

  • and begins to turn grey. Basically, it stops adding color to the hair. Gray hair tends

  • to occur earlier in Caucasians and later in Asians.

  • It's important to point out, that not ALL babies are born with blue eyes. This mainly

  • occurs with Caucasian babies, maybe because of the lower levels of overall melanin due

  • to the lighter skin tone. Babies of Asian, African and Hispanic genetic heritages will

  • likely be born with dark eyes that stay dark.

  • Funnily enough, 10-15 percent of Caucasians report their eye color continued to change

  • into adulthood, so it's possible your peepers are still not settled!

  • What's your favorite eye color? What do you wish you had?

  • Tell us in the comments and make sure you subscribe to DNews for more science! We're

  • here twice a day, every day of the year. Do you have questions? Let us know on Twitter

  • @DNews or me @TraceDominguez. Thanks so much for watching!

You might think your hair and eye color are permanent, but in reality, they could change


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B2 中高級 美國腔

為什麼我們的頭髮和眼睛的顏色會改變? (Why Do Our Hair And Eye Color Change?)

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    Ashley Chen 發佈於 2021 年 01 月 14 日