When ultraviolet sunlight hits our skin, it affects each of us
a little differently. Depending on skin color, it will take
only minutes of exposure to turn one person beetroot-pink, while another requires hours to experience
the slightest change. So what’s to account for that difference and how did our skin come to take on
so many different hues to begin with? Whatever the color, our skin tells an epic tale
of human intrepidness and adaptability, revealing its variance to be
a function of biology. It all centers around melanin, the pigment that gives
skin and hair its color. This ingredient comes from skin cells
called melanocytes and takes two basic forms. There’s eumelanin, which gives rise
to a range of brown skin tones, as well as black, brown, and blond hair, and pheomelanin, which causes the
reddish browns of freckles and red hair. But humans weren’t always like this. Our varying skin tones were formed
by an evolutionary process driven by the Sun. In began some 50,000 years ago when our
ancestors migrated north from Africa and into Europe and Asia. These ancient humans lived between
the Equator and the Tropic of Capricorn, a region saturated
by the Sun’s UV-carrying rays. When skin is exposed to UV for long
periods of time, the UV light damages
the DNA within our cells, and skin starts to burn. If that damage is severe enough, the cells mutations can lead to melanoma, a deadly cancer that forms
in the skin’s melanocytes. Sunscreen as we know it today
didn’t exist 50,000 years ago. So how did our ancestors cope
with this onslaught of UV? The key to survival lay
in their own personal sunscreen manufactured beneath the skin: melanin. The type and amount
of melanin in your skin determines whether you’ll be more or less
protected from the sun. This comes down to the skin’s response
as sunlight strikes it. When it’s exposed to UV light, that triggers special light-sensitive
receptors called rhodopsin, which stimulate the production of melanin
to shield cells from damage. For light-skin people, that extra melanin
darkens their skin and produces a tan. Over the course of generations, humans living at
the Sun-saturated latitudes in Africa adapted to have a higher
melanin production threshold and more eumelanin, giving skin a darker tone. This built-in sun shield helped protect
them from melanoma, likely making them evolutionarily fitter and capable of passing this useful trait
on to new generations. But soon, some of our Sun-adapted
ancestors migrated northward out of the tropical zone, spreading far and wide across the Earth. The further north they traveled,
the less direct sunshine they saw. This was a problem because
although UV light can damage skin, it also has an important parallel benefit. UV helps our bodies produce vitamin D, an ingredient that strengthens bones
and lets us absorb vital minerals, like calcium, iron, magnesium,
phosphate, and zinc. Without it, humans experience serious
fatigue and weakened bones that can cause a condition
known as rickets. For humans whose dark skin effectively
blocked whatever sunlight there was, vitamin D deficiency would have posed
a serious threat in the north. But some of them happened to produce
less melanin. They were exposed to small enough amounts
of light that melanoma was less likely, and their lighter skin
better absorbed the UV light. So they benefited from vitamin D, developed strong bones, and survived well enough to produce
healthy offspring. Over many generations of selection, skin color in those regions
gradually lightened. As a result of
our ancestor’s adaptability, today the planet is full of people
with a vast palette of skin colors, typically, darker eumelanin-rich skin
in the hot, sunny band around the Equator, and increasingly lighter pheomelanin-rich
skin shades fanning outwards as the sunshine dwindles. Therefore, skin color is little more than
an adaptive trait for living on a rock that orbits the Sun. It may absorb light, but it certainly does not
reflect character.

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100 thoughts on “The science of skin color – Angela Koine Flynn

  1. The agricultural revolution is what actually whitened Europe and Asia. You can get vitamin D from meat. That’s why eskimos still have dark skin.

  2. Why are the Simpsons yellow? They're not Asians. And yes there are Asians in Springfield. They made Apu dark skinned to show he's Indian.

  3. Haha, my sister always wanted to get a tan but somehow never got one even after trying so much, then there’s me goes out one day (maybe 7 hours) outside and gets an immediate tan… haha I… never wanted a tan 🙁

  4. Does that mean that our body develops on its own over the years to adapt to what is best for the nature we live in, did I get this right? And if yes then the form that we are on today might change in few thousands years to adapt also?

  5. Come on people. You all have to start using your minds a bit more. Stop being influenced by anything you hear from someone using a couple of big words to get your attention. Educate your selves. This is not how skin colours came about. Even how clever it may sound, but try using just 1% more of your mind and you'll hear the stupidity in this video. I encourage you to watch it over again, listening carefully at every statement made, before you take this information and apply it to your lives. Time is precious

  6. How deep and beautiful is that:

    "It may absorb light, but it certainly does not reflect character."

  7. Nice seeing a lot of people appreciate their dark skin, but I’d also like to tell the people with really fair skin to also learn to love it. Fair skin is beautiful too and there’s no need to fake tan it

  8. 2016: no mot even gonna be in her reccomedations.

    2017: no YouTube doesn't even want me to see it

    2018?: NnNoOO!!!

    2019: SuRe

  9. "They traveled to countries away from the equator."
    Yay! Diversity!
    "Their dark skin contributed to Vitamin D deficiency."

  10. so Caucasians have the least amount of melanin and Africans have the most. I'm Asian, so I have more melanin than Caucasians but less than Africans, amirite?

  11. This Scientific FACT, needs to be taught in the classrooms starting with Kindergarten & Preschool and then re-emphasized more throughout the curriculum until high school graduation!…

  12. “O mankind, verily We have created you from a single (Pair) of a male and a female, and have made you into nations and tribes, that you may know each other. Verily the most honored of you in the sight of Almighty Allah is the most righteous” (Quran, 49:13).

  13. People dont judge people by their color anymore they judge them by their culture, which is normally followed by which type of person is associated with that culture.

  14. Melanin is an living organ and is apart of everything natural. Every entity natural to earth has melanin, non-melanin things are man made.

  15. I also learned from ancestry dna that with african Americans it doesn't matter what skin tone you have .to tell your full ethnicity. it is your face features.

  16. Light and all the vitamins that we get from the sun is not the only thing that determines some of our pigmentation… So can our diet; people that eat more animal protein will have a little darker skin tone than those that have a primary vegetable diet.
    I have seen a person’s skin color change right before my eyes… they had been eating primarily vegetables and chicken for several months then one day I decided to have a much richer meat meal and their skin color got a little darker immediately. And I have also seen a persons skin color do the opposite when they went from a primary beef diet to a chicken and veggie diet and their skin color got lighter.

  17. Blacks and whites are totally different "they have different DNA whites are omosapions "and blacks are omoerectus totally different species

  18. This doesn't explain where white people comes from, it only explains why some people of melanin have various skin types, completely excluding the Neanderthals inter-species mating. If the Eskimoes stayed the exact same dark pigment for thousands of years, why haven't they changed.

  19. Everyone needs to see this, every person is the same underneath the skin, it's literally just our protective layer. The science of the human body, it's actually amazing. Most people of color can trace their origins to the equator band, which is more exposed to the sun's rays. Racism is a social construct.

  20. Am north indian.

    My colour varies from time to time

    Am a chameleon changing from little whitish to darkish
    And I never wonder why

  21. I’ve realised that skin colour can make a drastic difference in someone’s appearance. Woooooh dark tan skin I find attractive 😍😍😍

  22. So is that why my mum is the only one in my family that gets sunburnt? (My brother, dad, sister and I have darker toned skin)

  23. Wait so if a person with darker skin lives in a place with less sunshine like in the north they will slowly become lighter over generations.

  24. Just because my African ancestors 50,000 years ago moved north now I can’t go outside for more than 30 minutes without being burned

  25. I’ll begin by saying any form of racism against anyone is horrible. It should never happen. But I’m not convinced that this explanation is completely accurate. Part of it make sense and parts of it doesn’t.. there are other factors to include other then just skin color. Such as bone structure for one. Things that sunlight should not have an effect on facial features which sunlight should not have an effect on.. I concede that I may be mistaken but I believe there is more to this other then the amount of sunlight.. nor do we know the amount of sun light or the climate of the African continent so many years ago. It could very well be that the African continent was lush and green at the beginning of the human race which if so would mean that there was no reason for people to evolve with dark skin.. we really just guess what happened and conclude that the most simple reason is the correct answer. But it may not be.. I don’t know what changes happened none of us really do.

  26. Can anyone please tell me how to remove phototherapy tan as my baby boy was very fair for 5days after born after phototherapy he is dark with uneven skin tone diaper area toes hands one side is fair remaing body dark plz tell how many months to get his original skin tone plz rply anyone with same problem and cured

  27. My friend gets sunburnt she is very white her eyes are hazel and her hair blonde . I get tanned my hair is long wavy brown ( a little bit dark ) amd my eyes are brown.

  28. What if my moms from northern China and my dads from southern China? My mom is a lot paler than my dad, so should I be in between?

  29. Am i the only one who is obsessed with my beautiful, white skin?✊ Thanks for the information, it's nice to know the history of skin

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