The science of skin color – Angela Koine Flynn

The science of skin color – Angela Koine Flynn


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.

100 COMMENTS

    It certaintly does reflect character just compare the culture and histories of both groups and the way they relate among themselves and with other peoples and the planet itself.

    People who support or do racism are worse than animals because even animals don't differentiate and judge each other on basis of skin or fur colour
    . I😅😁

    Very weak. You didn't talk about Neuro melanin.you didn't talk about how these white people went Savage in the caves of Europe

    Wrote was fake it was fiction so look up some of these FACTS before replying to me in your feelings!!! I have tons of REAL FACTS!!!! Bye 👋 bye!!!

    Comments about racism in 3, 2, 1…
    I’m against racism, yet, can we stop thinking about it? This encourages it

    If there are 10 skin tones, and the higher the numbers are, the darker the skin, my skin tone would probably be a two. I'm screwed if I go in the sun.

    People talk about racism towards darker skin colors/more melanin but I think sadly in our society it can go both ways.

    It is true that sadly our history is tainted with racism towards darker skin colors but recently there has been racism/discrimination towards whiter skin colors.

    When I was teenager and even today people will say rude things to me like “wow are you a ghost? You are so white. Get some sun”. When I was a baby I had these super red cheeks. Some people thought it was cute but little did they know my skin felt like it was 🔥on fire all the time. Mom never used sunscreen. Normally my face would burn but for whatever reason my hand adapted and was the only place I would tan. I only had probably a very short three year period where all the sunburns gradually darkened my skin to protect me from sunburn. But it didn’t last and I always got white again and then the cycle of sunburn repeats.

    The video mentions evolutionary adaptation to our environment. But there is always a small percentage of people inhabiting an area for generations in an environment that is not suitable for their skin type. If my parents never immigrated to a cooler environment, I think I would be burning all year round. Granted I was born with some genetic mutations so I am an anomaly.

    There are advantages and disadvantages as explained in this video for both sides of the spectrums. More or less UV protection or more or less vitamin D production. I wish people would pay less attention to skin color and just appreciate the diversity and what or skin does for us.

    so if dark-skined people live somewhere the sun isn't very bright, they need a vitamin D supplement

    That makes it quite comical: “I hate you because your exposure to a different climate has differed our skin tones”

    I just really dont get why there are 800 dislikes….. there is nothing wrong about what the lady said in the video..

    People are all the same we just evolved differently but we must remember, we’re all still human. We’re the same people

    I’m half white half Asian. My mom is Filipino, her family is very tan. My dad is white, I don’t sunburn I tan, my dads side always burns while I always tan that it’s annoying. I hate having glasses in the summer because it creates an awkward tan line. I have been burned, but it was just my nose peeling. I still put on sunscreen, just so I can be protected from the sun.

    So if you have dark skin, and live in North area where there is small amounts of sunlight, you will lack vitamin D and have weak bones?

    When I was little I had a theory that when a person lives in a different country for a very long time their appearance will slowly and subtly change, I guess it's kind of correct haha

    I’m so happy this comment section is really open to different races and talking about racism, great job!

    I was born a litteral Snow White. The parts where I’ve never tanned are comparable to milk. It takes me at least an hour to get sunburned.

    according to this Trump is right, we shall put the person were they belong by their skin color. 😂😂😂😂 irony

    I had this question my whole life "If people who was rich in melanin was 1st before people who had less melanin then why, how did racism started cause people rich in melanin was 1st so how did they take over us like that?

    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.

    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.

    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 🙁

    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?

    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

    How deep and beautiful is that:

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

    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

    2016: no mot even gonna be in her reccomedations.

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

    2018?: NnNoOO!!!

    2019: SuRe

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

    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?

    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!…

    “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).

    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.

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

    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.

    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.

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

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