The Strange Case of the Missing Sunscreen Gene

The Strange Case of the Missing Sunscreen Gene


Thanks to Skillshare for supporting this episode
of SciShow. There’s nothing more annoying than coming
back after a day at the beach or a sunny vacation and noticing that there’s a perfect outline
of your sunglasses on your face. You’ve got yourself a nice tomato-red sunburn,
which is never pleasant. Not to mention the whole skin cancer thing. But some organisms don’t need to worry about
sunscreen at all, because they just make their own. And a few years ago, scientists discovered
that almost all fish, birds, amphibians, and reptiles at least have the genes for it. For those of you keeping track at home, that’s
every major group of vertebrates besides us mammals. And how we lost those genes is almost as strange
to think about as the way we acquired them in the first place. In the 1960s, biologists discovered that some
marine algae, bacteria, and corals could protect themselves from the ultraviolet rays in sunlight
by making compounds called mycosporine-like amino acids, or MAAs. Unlike many of the compounds in the sunscreen
we use, which work by scattering or reflecting UV light away, these MAAs absorb UV light. Two decades later biologists found a similar
compound, called gadusol, in fish and their eggs. Now, up until that point, scientists thought
only microbes could make their own sunscreens and that fish got theirs by eating those microbes. But then, in 2015, researchers found that
zebrafish could make gadusol and figured out which genes were responsible for making it. Once they’d identified those genes, they
searched for them in the genomes of other animals. That’s when they discovered that almost
all birds, reptiles, amphibians, and other fish have them, too although it’s still
unclear whether these animals actually express the genes and make their own UV-blocking compounds. Since so many groups of vertebrates have these
genes in common, they were probably passed down from some of the earliest back-boned
creatures. And researchers think those animals got the
ability to make gadusol around 500 million years ago, from algae. Instead of the genes being passed from parent
to offspring, the algae would have passed their genes to animals through a process called
horizontal gene transfer, which can happen between totally separate types of living things. We don’t know exactly how it happened in
this case, but the basic idea is that at some point, algae got into the cells of an animal,
which then incorporated some of the algae’s DNA into its own genome. That DNA included the genes for making gadusol,
which were then passed down to the animal’s offspring, and continued to be passed down
for another few hundred million years in almost every vertebrate except us mammals. Over the course of our evolutionary history,
we seem to have lost the genes. And that’s probably because we weren’t
always sun-loving creatures. We’re used to mammals dominating the earth,
and it’s been that way since not long after the extinction that wiped out the non-avian dinosaurs 65 million years ago. There’s a reason paleontologists call this
era “the Age of Mammals.” But around 250 million years ago, mammals
actually spent most of their time in the dark, which helped them avoid the massive dinosaurs
roaming around during the day. Spending so much time in the dark is how mammals
gained many of their distinctive features, like fur and a heightened sense of touch. These kept them warm and allowed them to hunt
for food without too much light. But the darkness also meant mammals lost some
features that weren’t so necessary for survival like being able to make gadusol. A random mutation probably sprung up in the
DNA of a few of these very early mammals, changing their genome so it no longer coded
for making gadusol. If that had been a big deal for their survival, most individuals with that mutation wouldn’t breed and pass the mutation on. But since you don’t need to make sunscreen
if there’s not much sun to shield yourself from, the mutation hung around. Over time, more mutations built up, and eventually
the gene cluster was lost. It’s the same deal with the West African
coelacanth, one of the few non-mammalian vertebrates that doesn’t have the gadusol gene. It’s a fish that lives in a dark cave and
feeds at night. Of course, these days plenty of mammals have
evolved their own ways to protect themselves from the sun. Elephants roll around in the mud. Hippos secrete their famous blood-colored
sweat. And most humans have at least some of the
pigment melanin, which, like gadusol, absorbs UV light. Our ancestors evolved the ability to make
melanin when they lost their dark fur, around 2.8 million years ago. It only absorbs about 3/4 of UV light at most,
though, and people with lighter skin don’t have very much of it in the first place. So it’s still important to slather on sunscreen
if you’ll be spending time in harsh sunlight, at least for now. Researchers are looking at ways to make gadusol
in the lab, and they’ve already had some success with genetically engineering yeast
to produce it. The advantage is that unlike the compounds
usually found in sunscreens, which can wash off our bodies and harm corals, gadusol is environmentally friendly because it’s already in the marine environment It could even come in pill form someday, which
means your days of dealing with sticky lotion or accidentally spraying yourself in the eyes
could be numbered. We may not be able to get these fish-sunscreen
genes back, but we can at least find ways to use them to our advantage. Has all this talk of sunlight made you realize
it’s been way too long since you had time to relax? If you want to get all your tasks done faster
so you can go play out in the sun, you might be interested in this Skillshare class on
How to Skyrocket Your Productivity in 10 Steps, taught by corporate psychologist and management
consultant Dr. Patricia Thompson. The strategies are all scientifically based,
and since Dr. Thompson goes through some of the studies behind them, you’ll learn some
psychology along the way. Of course, she also gives you plenty of practical
tips to help you go from “yeah, I know I need to focus” to actually getting things
done. And right now, Skillshare is offering SciShow
viewers 2 months of unlimited access to this class, as well as over 20,000 others for free! There are classes on everything from baking
to programming, so whatever you’re interested in, there’s something for you. Just follow the link in the description to
check it out!

100 thoughts on “The Strange Case of the Missing Sunscreen Gene”

  1. 1:50 "Horizontal Gene Transfer"
    MORE ON THIS, PLEASE!
    Like, how does it happen from eating? What about kissing? Does it only happen via bacteria, or what about viruses, which rewrite DNA???

  2. I don't understand people who insist on going to the beach and NOT putting sunscreen, just because they want to get a tan. Then, they complain about getting sunburned. Just like people who complain about being hangover every weekend but they won't stop drinking.. ugh, so annoying.

  3. I am an organism that doesn't have to worry about sunscreen. I can spend almost all day outside and I'm fine.
    Yes I'm 100% white not dark,and I spend my day working outside here in Arizona and I don't get a sunburn.
    If you get sunburns it probably means you need to spend more time outside I the sun. I'm sure after a while you'll stop getting burned. Atterall white people spent literally thousands of years outside in the sun most of the day every single day. And historically they practically didn't even know what a sunburn even was.
    Stop using sunscreen just spend time outside. This isnt rocket science it's uncommon sense. Get it…. because sense isn't common anymore? Because your great grandparents didn't even have sunscreen and they were all fine busy never getting sunburns. Use your brains think actual thoughts instead of repetitive memetic data

  4. I'll throw you some interesting topics for episodes:
    Could we theoretically fix our vitamin C generating gene and no longer worry about scurvy?
    Could we ingest some enzymes and get nutrition from wood pulp, also known as dietary fiber?

  5. so gadusol is like…"chemical" sunscreens? stuff like abovenzone, methoxinamate etc? if the human gene was gmo-ed, how would people who can't use chemical sunscreens (hence can only use "physical" sunscreen like zinc oxide and titanium dioxide that reflect instead of absorb sunlight) react? would it even work on such folks? or would gadusol only be implemented into genes of people who are able to apply "chemical" sunscreens without side effects?

  6. There must be another mechanism to not burning from the sun. I was doing a therapy where I drank 12 glasses of fresh cold pressed vegetable juice daily (I pressed it myself) for three years. During that time, I could go out in the sun all day and not burn. I am fair skinned with blonde hair. I used to burn. During this time, I also took fewer soap baths and showers to avoid chlorine and fluorine. I bathed once a week with soap, but the rest of the week I just did spot cleanups.
    Go out in the sun, it's free vitamin D. But don't wash your skin with soap for 12 hours to let the D formed on your skin to soak into your body.
    I was also doing daily coffee enemas, which stimulate your liver to produce glutathione, which causes your skin to lighten, and feel very soft.
    I wonder if taking vitamin D, glutathione, carotene, and chlorophyll would do the same thing.

  7. The Curse of Cain is the reason we can't protect ourselves naturally from the sun.
    The sun shall burn us like fire, and the mark shall be visible on our skin.
    .
    .
    Fanatics thought black skin was the mark, but it's actually white skin.
    It's very easy to figure out.
    A black man and a white man go to the beach,
    neither have sunscreen.
    Which one get's sun-burnt first?

  8. Pill form?! That's super unnatural, how is it even supposed to work, we need to do some horizontal gene transfer ourselves…

  9. 03:50: "…and people with lighter skin👦 don't get much of it anyway."

    This reminds of that science article from a few years back that said Superman – who gets his powers from ☀️ – should be Black.🏋🏿‍♂️

  10. If feel like we are due for a new intro song. That way we could all hate the new song and bond together over that shared hate. Then one day you'll release a third song and we'll all say we prefered the previous one, keeping the community bonding cycle alive.

  11. There is a blotch on the left E on your EngineeringExplained shirt! REEEEEEEE
    Hmm? OH! Yeah, very nice video about the sunscreen gene too btw 🙂

  12. I wear my hair down over my face some times… I went to a music show in Texas several years back, and I got a sun burn on just one side of my face… but not the other. it was so weird and unpleasant.

  13. …are you saying that the gene for Gadusol is absolutely,-nonextant in humans, or just that Gadusol is not produced in human skin cells—in other words, is there no junk-gene that would produce Gadusol if it were 'complete, correct, unbroken, not defeated, not recessive…

  14. The part of having a full, Protective fur coat protecting mammal ancestors would seem to have more of a driver to losing the gene than being nocturnal or burrowing animals.

  15. Well there are viruses that can manipulate our genes so isn’t it possible that algae could’ve done the same thing?

  16. I think I must have devolved then. I have pasty white skin, practically blinding white, but I neither tan nor burn. When I was younger, I would go out to the pool in my apartment complex daily, lay there for hours with no sun block trying to get a tan, but to no avail. When I die I'm going to donate my skin to NASA so they can make better space suits that will allow astronauts to space walk right up to the sun.

  17. HOLDUP! "Gadusol is enviromentally friendly, because it's already in the marine enviroment". That it is in somewhere doesn't mean it's good for the place where it is in. Plastics are there too and oil.

  18. We also lost the ability to make our own vitamin C way back when and that isn't cool when you consider a goat can make 100 grams a day when sick and that ain't for nothing.
    CBD or cannabidiol helps melanocytes produce melanin. Yes, I said that right.
    Chem Biol Interact. 2017 Aug 1;273:107-114. doi: 10.1016/j.cbi.2017.06.005. Epub 2017 Jun 7.
    Cannabidiol upregulates melanogenesis through CB1 dependent pathway by activating p38 MAPK and p42/44 MAPK.
    Hwang YS1, Kim YJ2, Kim MO3, Kang M3, Oh SW3, Nho YH4, Park SH5, Lee J6.
    Author information
    Abstract

    Melanogenesis plays a critical role in the protection of skin against external stresses such as ultraviolet irradiation and oxidative stressors. This study was aimed to investigate the effects of cannabidiol on melanogenesis and its mechanisms of action in human epidermal melanocytes. We found that cannabidiol increased both melanin content and tyrosinase activity. The mRNA levels of microphthalmia-associated transcription factor (MITF), tyrosinase, tyrosinase-related protein (TRP) 1, and TRP2 were increased following cannabidiol treatment. Likewise, cannabidiol increased the protein levels of MITF, TRP 1, TRP 2, and tyrosinase. Mechanistically, we found that cannabidiol regulated melanogenesis by upregulating MITF through phosphorylation of p38 mitogen-activated protein kinase (MAPK) and p42/44 MAPK, independent of cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) signaling. In addition, the melanogenic effect of cannabidiol was found to be mediated by cannabinoid CB1 receptor, not by CB2 receptor. Taken together, these findings indicate that cannabidiol-induced melanogenesis is cannabinoid CB1 receptor-dependent, and cannabidiol induces melanogenesis through increasing MITF gene expression which is mediated by activation of p38 MAPK and p42/44 MAPK. Our results suggest that cannabidiol might be useful as a protective agent against external stresses.

  19. Australia: sunscreen year around, lead-lined head to toe, blue man group style suit during summer! Lol, or at least what it may become in future years?!

  20. So recalling your 4th Nov episode (https://youtu.be/4pU9O_LFxmk?t=411), the mammals that spent their days hiding to avoid dinos, would then need to contend with Velociraptors lurking around at night?

  21. Wow, Stefan Chin is getting pretty buff. Nice.
    I could certainly use a gadusol pill — I’m losing what little melanin I had.

  22. Or… you know… just build up a tan.

    When I was working a job at a garden center, within a week of working there I was able to build up a tan dark enough to allow me to work a full 8 hour shift in the sun without any sunscreen.

    Edit: Although I suppose it depends what your ethnic background is. I'm 3 quarters European so I look white, but I am also 1 quarter Chinese so I guess that lets me build up a tan when I need it.

  23. And acute hearing! Let's not forget one of the most important mammal evolutions is the "migration" of rear-jaw bones to the ear where, adequately reduced in size, they make for excellent amplifiers.

  24. I'm so fair that I don't burn, I burst into flames! And I think I've tried every single kind of sunscreen and sunblock, but I still end up burning.. the sun hates me 😕

  25. I like how science is always telling you stuff they can't possibly know like that human beings had fur and stayed inside to avoid dinosaurs- those are theories or hypotheses not facts

  26. I spend all day outside in Colorado and California throughout my life and I’ve never gotten a sunburn. However I have gotten tans before which is kinda sad due to the fact that you’re cells kill themselves for you to counter mutations from the sun rays and their deaths is what causes the extra pigment in a tan

  27. I wont burn without suncreen i just get faily tan but if i put any suncreen on at all i get severly burnt in the sun idk why

  28. I'd give anything for a sunscreen gene. Even people with type 3+ skin have no idea of the pain of 1st degree sunburns 😭

  29. Have they done studies comparing different ethnic backgrounds of people like those that eat more fish in a diet to see if some people have acquired the gene and what about GMOs that's in direct but it's still an issue. What exactly makes that safe again what was that argument. You are or can be part of what you eat proven.

  30. I wonder if horizontal gene transfer happens due to the "accidental" creation of virus-like offshoots, which then infect cells of different species. Anyway, it sounds like we could put the gene back into our DNA if we wanted. Let's get started on that.

  31. Now ponder on what that means if we temporarily lose Earth's magnetic field… As has happened multiple times in Earth's History.

  32. The idea of being able to take a pill in the morning instead of slathering on sunscreen is VERY attractive to me. I can't imagine it would be good for vitamin D levels though.

  33. It's probably also not a concern since most mammals are covered with fur. They don't need sunscreen like we bald mammals do.

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