Chromosome 15 – Eye colour

[MUSIC PLAYING] I’m in London to talk about the eye. It’s one of the most impressive feats of engineering that.

[MUSIC PLAYING] I’m in London to talk
about the eye. It’s one of the most
impressive feats of engineering that you’re
likely to see. But I’m not talking about
the London Eye. I’m talking about
the human eye. [MUSIC PLAYING] Now we know that the eye is an
incredible mechanical marvel. But when you stare into
someone’s eyes, you’re not thinking about engineering. The first thing that you usually
notice is the colour, and the colour of the eyes is
down in part to a gene on Chromosome 15. Now that gene is known as
OCA2 or, to you or me, oculocutaneous albinism II. Now in order to work out how the
colour in the eye works, let’s have a closer look. [MUSIC PLAYING] The coloured part of the
eye is the iris. And in the iris, the OCA2 gene
gives instructions for the production of a pigment
called melanin. Now when lots of melanin is
produced, the result is dark brown eyes. [MUSIC PLAYING] When little or no melanin is
produced, we get blue eyes. [MUSIC PLAYING] Now the blue doesn’t come from a
coloured structure or a blue pigment, but arises from light
being scattered through the iris in a similar way to how
light scatters through the earth’s atmosphere and
gives us a blue sky. [MUSIC PLAYING] Although we don’t yet fully
understand the genetics of it, it’s the same kind of cells
and the same production of melanin that causes our skin
to darken a few days after we’ve been in the sun. Although in the middle of winter
in England, I think that’s unlikely to happen
anytime soon. [MUSIC PLAYING]

50 thoughts on “Chromosome 15 – Eye colour”

  1. There was no engineering that went into the human eye.  And if you want to say it was engineered, then given the universe of possible eyes, the human eye is a huge failure considering the capabilities of its engineer.

  2. Much better than the last one, but still it could go a little deeper, I would like to see these at around 5 minutes long and like the comment I saw from the last video, I would also like to eventually see much more in depth versions.

  3. So, what causes green eyes? I'm not talking about hazel, or a mix of brown and blue like the last eye shown in the video, but dark, pure green eyes. Just curious.

  4. i think green eyes are a result of less melanin in the iris. not like blue which have almost no melanin….i have green eyes so i did some research on it. thanks for the video though. its great!

  5. 2:04 is my fiance's eye color.  My eyes are dark brown.  I wonder what the chances are of our children getting his beautiful grayish green eyes.

  6. Sonya Anew Don't listen to what people say they will never understand why God did what he did you can study all you want blah blah I have almost black eyes I am medium skin well olive skin tone my husband is pale white Green eyes but mixed with yellow and other colors just beautiful again my eyes are almost black crazy how dark they are my hair is black and thick as well .. My mother is my skin tone my father is light skinned tone all my siblings are light I'm the dark child. My husband's Parents are both dark as well mother not so much lighter than I am father way darker we are all Mexicans family is from Jalisco Mexico. . My Great grandfather was Italian blue eyes His wife my Great Grandmother was straight up dark dark Indian .. So long story short both sides of our families have green blue hazel light brown eyes .. Dark skin and pale skin .. Dark black hair and redish blonde well everyone thought Our son would come out dark light brown like me and have thick black hair well when he was born viola Along came this beautiful pale pale white baby with gray eyes bald as can be and he is now 16 months most beautiful Blue Eyes I've ever seen with a hint of green and yellow .. Pale skin rosy cheeks and still not a lot of hair but it's blonde and redish looks nothing like me he only got the nose and my Dimples… ♡ Anything is possible. ….

  7. My eyes change color not every year or so no. every 5 minutes there like a glass ball full of color and i often have 3 or 2 different colors in ONE eye at a time and its been like this for my whole life and people go crazy over them like some times the colors are split right down the middle its hard to explain. think of a glass ball like i said earlier and fill it with like 2 or 3 colors now shake it up and watch the colors move around but dont mix with each other. thats my eyes. I can't find a single person who has the same as mine most are just 2 separate colors or you get people who are saying there eyes change every so often each year but i never notice can someone like… idk tell me wtf is up with my eyes

  8. You have green eyes when you have to little melanin to have brown eyes but too much melanin to have pure blue eyes, so green is appears in between brown and blue.

  9. My eye color is grey blue, yet no matter how much I search, I have yet to find any data that covers that exact combination.

  10. My eye color is grey blue, yet no matter how much I search, I have yet to find any data that covers that exact combination.

  11. American here, I get as white as this guy in the video in winter too lol. Hairy is dirty blonde, hazel eyes. 6'3 190 pounds. But now I'm 33 and my hair has some gray in it thanks to my ex wife

  12. My eye colour is like blue and than towards the middle there's light brown, I'm not sure if there is a specific name for this colour, could someone help me?

  13. If it's due to light, wouldn't the color disappear in the dark where there is not light available to scatter through the eye? Or when you eyes are closed?

  14. I actually have central Heterochromia. I’d love to know how it happens to people. I have both recessive eye color and hair color from my family. I don’t look much like my family.. but I realized that I should be greatful for that. I am beautiful either way.

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