How & Why Earth Went From Purple to Green (Twice!)

How & Why Earth Went From Purple to Green (Twice!) | GEO GIRL

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Күн бұрын

Did you know that Earth used to be purple?! Actually, there were TWO periods in Earth's history during which it likely looked more purple than green like it is today. The reason land on Earth looks green from space today is plants, but on early Earth, before about ~500-400 million years ago, plants hadn't evolved yet! So what color was early Earth?
To answer this, we first need to understand what makes plants green. It is the pigment plants use for photosynthesis that makes them green. These pigments actually evolved before plants in microbes like cyanobacteria and later in algae. Therefore, cyanobacteria and algae may have made early Earth look green even before plants. But what about before cyanobacteria? It has been hypothesized that purple pigment-using phototophs, like haloarchaea today, may have evolved before green pigment-using photosynthesizers. This means that before cyanobacteria came along, Earth may have looked purple! Now, we even think there may have been a second "Purple Earth Event" after the evolution of green cyanobacteria due to 'purple anoxygenic photosynthesizers' throughout the boring billion! In this video, I go over both of these hypotheses, the evidence behind them, and the intriguing implications of these Purple Earth Events! ;D
GEO GIRL Website: www.geogirlscience.com/ (visit my website to see all my courses, shop merch, learn more about me, & donate to support the channel if you'd like!)
0:00 Life on Early Earth
1:15 Photosynthesis on Early Earth
2:56 Contrasting Colors of Photopigments
4:49 Purple Earth Hypothesis
5:25 Phototrophy vs Photosynthesis
6:22 Purple vs Green Phototrophs
9:43 From Purple To Green Earth
11:24 Evidence for Purple Earth
14:29 Rise of Photosynthesis
14:57 Second Purple Earth?
19:01 Transition to Green Earth
19:41 Using Pigments to Find Aliens?
References:
DasSarma & Schwieterman, 2018: api.semanticscholar.org/Corpu...
Zhao et al., 2023: doi.org/10.3389/fmicb.2022.10...
Philippi et al., 2021: doi.org/10.1038/s41467-021-25...
Sparks et al., 2006: www.researchgate.net/publicat...
Johnston et al., 2009: doi.org/10.1073/pnas.0909248106
Lyons et al., 2021: doi.org/10.1089%2Fast.2020.2418
Earth System History: amzn.to/3v1Iy0G
Hey there, Earth enthusiast! Check my favorite Earth-friendly products:
Bamboo toilet paper: shrsl.com/3cvku
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Compostable tableware: shrsl.com/3cvkz
Compostable trash bags: shrsl.com/3cvl0
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(Just click link, press get started, take the free C footprint quiz, then choose how much you want to reduce your footprint by donating to the C sequestration projects they're funding!)
Non-textbook books I recommend:
Oxygen by D. Canfield: amzn.to/3gffbCL
Brief history of Earth by A. Knoll: amzn.to/3w3hC1I
Life on young planet by A. Knoll: amzn.to/2RBMpny
Some assembly required by N. Shubin: amzn.to/3w1Ezm2
Your inner fish by N. Shubin: amzn.to/3cpw3Wb
Oxygen by N. Lane: amzn.to/3z4FgwZ
Alien Oceans by K. Hand: amzn.to/3clMx1l
Life's Engines: amzn.to/3w1Nhke
Tools I use as a geologist/teacher/student:
Geology field notebook: amzn.to/3lb6dJf
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Disclaimer: Links included in this description might be affiliate links. If you purchase a product or service with the links that I provide I may receive a small commission, but there is no additional charge to you! Thank you for supporting my channel so I can continue to provide you with free content each week! And as always, let me know your topic suggestions in the comments down below!

Пікірлер: 468

@GEOGIRL 11 ай бұрын

Hey guys! I thought I should mention that yes, I kinda sorta stole this video idea from pbs eons haha, but this video is not meant to repeat what they've said or discredit their video in any way. I actually made this video because I felt like there was more to discuss on this topic and I hope that my video complements their video by providing additional background and information about the potential second purple earth event! So I hope you enjoy, and if you are interested in checking our pbs eons' video on purple earth I highly recommend it! -> kzfaq.info/get/bejne/f69xYM6Qx6jHfGQ.html

@rursus8354 11 ай бұрын

I don't watch PBS eons because of their overproduced videos that I find insufferable, so go on with pilfering ideas! You on the other hand, sound exactly like a university professor doing his/her slideshow. That's my way.

@davidniemi6553 11 ай бұрын

While PBS Eons covers a really broad range of material, for areas in your expertise (which happen to coincide with many of my interests) you add a lot more information and really thorough and clear explanations I do not see anywhere else. Thank you!

@BillySugger1965 11 ай бұрын

Hey Rachel, have there been any developments in research into abiogenesis in the last few years? Are we any closer to fleshing out a plausible mechanism? Would you give us a video on this if there is anything new to reveal please? 😊

@kiedranFan2035 11 ай бұрын

So if I'm not mistaken then plants could be engineered to carry the bacteria rhodopsin too and made to look blackish instead to shades of other colours depending on the concentrations of these two light pigments in this dual system. If so then interesting.

@ReggieArford 11 ай бұрын

Beg pardon, but humans DO photosynthesize! (~6:00) We make Vitamin D using sunlight.

@summerlovinxx 10 ай бұрын

born too early to live on a purple planet, too late to live on a purple planet, but just in time to be given a very informative video on when it was around. very cool of you, thank you!

@robinleow185 11 ай бұрын

It is good you end up with astrobiology application. Reminding people geoscience goes beyond Earth and it is not a bad thing (geoscience) as many people thought.

@Bostonceltics1369 11 ай бұрын

Earth 🌍 is not in a vacuum. . . Oh wait 😅

@VeganSemihCyprus33 11 ай бұрын

Dominion (2018)

@JariDawnchild 10 ай бұрын

@@Bostonceltics1369 My brain won't shut up lol.

@jeremyinthewild 11 ай бұрын

Our body uses energy from the sun in the process of creating Vitamin D, I guess that would be phototrophy as well! Actually the history of the production of Vitamin D goes all the way back to early photosynthesizers, with the possibility that they made it as a sort of natural sunscreen to protect sensitive molecules inside. It's a bit of a rabbit hole itself haha

@bramvanduijn8086 10 ай бұрын

I don't know if it is phototrophic, since it doesn't give us a net increase in energy, but it is photosynthetic since it gives us vitamin D.

@JariDawnchild 10 ай бұрын

@@bramvanduijn8086 I was going to argue that it is, since we're diurnal, but I'm not sure if it would count lol. Or does it? Vitamin D is also essential for our immune systems, bone health, mental health, our intestines, etc. It still might not count, but my brain went there lol.

@lolaby2 10 ай бұрын

Apparently we used to make more than vitamin D too. When we started having a fruit based diet we were poisoning ourselves with too much vitamin B. So we lost the ability to make our own!

@AuroraCalifornica 3 ай бұрын

Also our retina converts light into chemical energy and then into action potentials, which is also phototrophic!

@goyoelburro 11 ай бұрын

This stuff blows my mind. I wish more people knew about the early Earth. They didn't teach my kid this in school at all. I try to teach her this myself...

@GEOGIRL 11 ай бұрын

That is so amazing that you teach your daughter this stuff! I wish I was taught more of this stuff growing up. I myself am not an expert in teaching audiences younger than college age but I do think we should make an effort to provide at least some of this information in classes before college! Hopefully that will be the case in the future :)

@josepablolunasanchez1283 11 ай бұрын

"Where Did The Moon Come From? - Do We Really Need the Moon? - Preview - BBC Two" is a great video for students too. Theia was a planet of the size of Mars that was trapped in the same orbit of Earth. Gravity anomalies ended up making them to get close and collide. The early moon was way closer and looked, tides must have been tall, and Earth days lasted only 5 hours. Imagine the early Earth, a surface of molten radioactive lava, with a huge moon in a short day.

@thechosenone5644 10 ай бұрын

Same experience. Some of the information on hydrogen sulfide bacteria was in a bio textbook we used but we barely mentioned it in class.

@caiociardelli 9 ай бұрын

Rachel, I'm a postdoc in geosciences (more specifically, in seismology) at Northwestern University, and found your channel less than a week ago. I'm absolutely amazed by the extremely high-quality content you have. I'll probably watch all of your videos! 😁 Your channel is, by far, the best I've ever seen on geosciences! Congratulations on the amazing work you have been doing by teaching so well! If you intend to become a professor (well, actually, you already are 😊), you will be an amazing one! Fortunately, now we have KZfaq to spread the kind of high-quality content such as yours to the four corners of the world! 😃

@GEOGIRL 9 ай бұрын

Wow this comment truely made my day! I do in fact plan on becoming a professor (for in person students haha). I actually have a postdoc position lined up at university of south carolina starting in the spring, and they are going to let me teach a course during my postdoc! :D Anyway, thank you so much for the kind words and encouragement! It means so much coming from a seismology doctor! ;) Best of luck with your postdoc and future endeavors!

@caiociardelli 9 ай бұрын

Thanks! That's awesome! I'm sure you'll do great in your future postdoc 😄 Whenever my advisor is traveling, she asks me to teach in her place for a few days, which I always love :) But I didn't get the chance of teaching a whole course yet (although I may, early next year). Right now, I'm focusing on applying for a faculty position in geodynamics in Brazil (my home country). I found your channel precisely because I'm studying a lot. You explain really, really well 🙂 I wish you can keep the amazing job you're doing 😄 Good luck too!

@tedetienne7639 11 ай бұрын

Thank you for mentioning that we have retinal pigments in our eyeballs at around 11:48. I was getting confused why this purple pigment was called “retinal” until then. I had to look that up: It’s the light-sensitive compound that detect light in our eyes - hence “retina” - and our body produces it by breaking down Vitamin A. I was wondering what the connection to microbes was! I learned some biology today!

@thekaxmax 11 ай бұрын

'Retinol' is the molecule

@VeganSemihCyprus33 11 ай бұрын

Dominion (2018)

@rosepetals8181 10 ай бұрын

Bilberry,puts the purple back in your eyes,OHH THE COLORS💜🤗💜😘👍

@tigertiger1699 11 ай бұрын

🙏🙏🙏🙏 incredibly interested in early life… and the immense volume of earth time…. Blows my tiny mind…🙏

@tigertiger1699 11 ай бұрын

🙏

@shovelspade480 11 ай бұрын

I feel like a teenager again, with a crush on Geo Girl. 🤣🤦‍♂😂💚🌍 Keep up the amazing work. Your quality shines through in the quality of these presentations. It's very inspiring.

@GEOGIRL 11 ай бұрын

Thank you so much! So glad you enjoy the videos :)

@danielszkup0403 11 ай бұрын

Gold Star Geo Girl ; you've obviously been studying the ruminations of English philosopher and physicist John Locke. Well done on another great presentation Geo Girl !❤🎉

@andrewsarchus4238 11 ай бұрын

Very interesting about the reciprocity of absorption between the purple and green photosynthesises. Another insight into why photosynthetic pigment is green is in the paper “quieting a noisy antenna” by Trevor ARP, SCIENCE 26 Jun 2020 Vol 368, Issue 6498 pp. 1490-1495

@mickwilson99 11 ай бұрын

Point to note from a once-upon-a-time biophysics student: thermodynamics dictate that energy absorption by phototrophic organisms must ultimately be balanced by ability to radiate heat i.e. it has to run hotter to colder else there's no work to be done. Chlorophyllic life, by absorbing photon at the red and blue end of the spectrum, are optimally emitting waste heat using wavelengths at which our (oxygen enhanced) atmosphere is very transparent. The rhototans, in absorbing the mid-enrgy but most prevalent photons could only dump heat as reddish or blueish photons, neither of which traverse our (oxygen-enriched) atmosphere.

@legendre007 11 ай бұрын

I love it when Jackson's chameleons change color, and now I can say the same about the Earth. 😊 ❤

@philochristos 11 ай бұрын

That was back when Barney roamed the earth.

@sciencenerd7639 11 ай бұрын

Wow, thank you for covering this topic. The metabolic diversity of prokaryotes is fascinating to me. I watched the eons video on this topic, but it left me feeling that I wanted more details, so this is exactly what I was hoping for. Also I feel like one time the channel it's okay to be smart did a video about purple sulfur bacteria but I can't for the life of me find it. So this was exactly what I needed.

@iansanford6544 11 ай бұрын

I've seen research on plants' color and the rate of energy absorption across the spectrum suggesting that green is an evolutionary choice to forgo the intense, volatile middle of the spectrum and instead opt for the stability of red and blue wavelengths to generate more reliable output. It follows (or precedes) quite neatly that the first adopters would use a less efficient, higher risk/reward but more accessible chemical pathway and that the organisms we see are descendants and optimisers of that lottery's winners.

@rebeccawinter472 2 ай бұрын

This is what I have seen too. It’s a compromise - avoiding getting “sunburnt” as it were - from absorbing too much radiation.

@nayr151 11 ай бұрын

Excellent video. You finally answered the question I’ve been having for years which is why plants reflect green when the solar spectrum peaks in green. Thank you!

@idlikemoreprivacy9716 11 ай бұрын

What an amazing communicator you are, you make everything so interesting!

@GEOGIRL 11 ай бұрын

Thank you so much! ;D

@caspasesumo 11 ай бұрын

Such a great series of explanations Rachel. This is one of my favorite of your amazing series of videos. My Father in law is an early adopter of Photovoltaic energy capture. Next time I see him I'm going to mention that he is an ancient Phototroph 😆

@GEOGIRL 11 ай бұрын

Thank you so much! I am so glad you enjoyed it, it is one of my favorites now as well :)

@satyr1349 11 ай бұрын

Fascinating as always, keep the good work up if you can!

@caspermcgonagle1532 9 ай бұрын

I like PBS eons but your videos are much more detailed then theirs and I actually feel like I understand the topic after watching your videos so thank you for making this.

@Anthocyanina 10 ай бұрын

wow, this was so fun to watch. this video has unlocked so many new things for me to learn about that i didn't know of at all. really cool!

@gryph01 11 ай бұрын

I had never heard of this before. It is interesting!

@galactic-beys 11 ай бұрын

so cool🦠💜🌎 great videos! thank you for all your time and efforts🍎

@davids82605 11 ай бұрын

As always thank you for your vids in which you are going deeper into subjects I've only been hearing about superficially but that interest me greatly~

@GEOGIRL 11 ай бұрын

Thanks so much! So glad you liked the deep dive ;)

@erikziak1249 11 ай бұрын

Finally the KZfaq algorithm suggested this video. I am subscribing and looking forward to check your videos. This is really quality content and deserves more views. I love how passionate, yet composed, you are in the video. Best wishes to you, your loved ones and this channel, Erik.

@GEOGIRL 11 ай бұрын

Thank you so much for the kind words! 😊

@LynxUrbain 11 ай бұрын

I just discovered your channel, and I really appreciate that you provide all your references. Many thanks to you!

@GEOGIRL 11 ай бұрын

Thank you! So glad you enjoy my content ;D

@Cygnus__X1 11 ай бұрын

i love how nerdy you are. Fun video! I always wondered why plants reflected green light instead of absorb it when we have a green star. now i know why!

@GotMyTowel42 11 ай бұрын

Thank you for making this. Your channel is supes underrated. ^^

@GEOGIRL 11 ай бұрын

Thank you so much!

@GotMyTowel42 11 ай бұрын

@@GEOGIRL You're most welcome :)

@geronimomiles312 11 ай бұрын

Both very interesting and explanatory! Well done , ( This really needs to be included in school bio classes , big time)

@mikaljan316 11 ай бұрын

this channel deserves way more subscribers!!

@arbodox 11 ай бұрын

Wow, this is super fascinating! I really appreciate these in-depth lecture-type videos on (astro)biology and geology, and I'm probably gonna spend the next few hours binging your videos! By the way, I'm the author of the purple planet image you used in your video and thumbnail. No worries though, because I actually feel pretty honored that a random 4-year-old SpaceEngine screenshot of mine made it into a KZfaq video of all things! Anyways, keep up the good work! :D

@GEOGIRL 11 ай бұрын

Wow thank you so much! And thanks for letting me use your image it is so beautiful!!🤩 I am so glad you liked the video 😊

@intothisworld 11 ай бұрын

Brilliant video, new fan and checking out your others

@ignazachenbach5406 11 ай бұрын

I never had any special affinity towards geology, but I like this channel. Subbed!

@JT-yq8br 11 ай бұрын

Just discovered this page & I immediately hit the subscribe button. Looking forward to watching all the videos, past & future. 🤗

@GEOGIRL 11 ай бұрын

Thanks so much! So glad you like my videos ;D

@barbaradurfee645 11 ай бұрын

You rock!❤❤❤

@harveytheparaglidingchaser7039 3 ай бұрын

That was fascinating. Thank you

@shadeen3604 11 ай бұрын

New discovery about past earth history thank you geo girl excellent

@rursus8354 11 ай бұрын

Couldn't it also be that green light photosynthesis developed in the green light in order for organisms not competing with *their own* retinal based phototrophy?

@GEOGIRL 11 ай бұрын

I am sorry, could you re-word the question? I am not sure I understand, I thought I tried to convey this point in the video so I want to make sure I understand what you are asking, thanks! :)

@ozachar 11 ай бұрын

I have learned a lot. Thanks!

@davidrogers8030 Жыл бұрын

No longer purplexed due to the light shed here.

@GEOGIRL Жыл бұрын

This comment is just the best

@jamesraymond1158 11 ай бұрын

Excellent. PBS Eons had a 10-min video on the same subject, Both are beautifully presented but this one goes into much more detail. "Complementary" (used later in the video) is a much better word than "opposite" to describe the different spectra,

@pequerobles 11 ай бұрын

this is an amazing channel. the website linked is great too ! V glad the algorithm recommended this channel for me

@GEOGIRL 11 ай бұрын

Thanks so much! So glad you like my channel ;D

@pequerobles 11 ай бұрын

@@GEOGIRL I love it, it's great. I have a 40 yr interest in these topics. You're videos are addictive. I'll probably end up watching all of them within the next few weeks 🙂

@lionnelmurimi651 11 ай бұрын

One of the few videos that I havent skipped ahead on because of some pointless chatter. Great job and I look forward to binging on the contents of your channel.

@thechosenone5644 10 ай бұрын

Did a cursory search, and different methods of photosynthesis have arisen independently in bacteria quite a few times. Would enjoy seeing a video comparing their methods

@barbaradurfee645 6 ай бұрын

Me too

@DenilsonBaiensedeLima-to1fy 11 ай бұрын

Beautiful! Good Sunday!

@GEOGIRL 11 ай бұрын

Thank you! ;D

@fabiana.4640 11 ай бұрын

Hi Rachel! I've become a fan of your vids. You give lots of info. For example, I have always tried to find how dense were the Carboniferous forests. And you explain this in your video about this period. Please, make a vid about THE AZOLLA EVENT. Was it true or is it pure speculation? Can a single plant produce an extinction event in an era where there were lots of hervibores that could specialize to control it's expansion?

@vi8898 6 ай бұрын

Your channel plays a pivotal role in transforming people's understanding of nature and the world around us. It serves as a catalyst for the EVOLUTION of mental comprehension, contributing to a deeper and more enriched understanding of our surroundings. Thank you for fostering knowledge and enlightenment! On behalf of ALL of humanity, Thank You!!! ;o)

@Alex.Holland 11 ай бұрын

I learned about this myself a decade ago, as a layman farmer. I noticed the nm gap for the solar peak and that was super counter intuitive to me. it didn't take much googling from that start point to stumble on this.

@josephjackson5088 11 ай бұрын

Your aura, it's purple! You gotta find it fascinating that for all we have learned we still have so much more to learn. Stay curious. Thanks Rachel.. 👍👍👍

@GEOGIRL 11 ай бұрын

Thank you so much! And yes, I am always amazed at how much we still have to learned, but it also makes me so excited to do so ;D

@takingbacktheplanet 11 ай бұрын

first of, first time watching and very interesting stuff (most of which i knew other than the fact the earth was once purple o_o)... secondly, I LOVE POWERPOINTS. also, no shame in taking ideas from PBS Eons - you have your own take and approach (and it seems lovely) - but they also have some of the best content. 😂

@ptredhead 11 ай бұрын

Great video, thanks! I appreciate the level of detail you go into. I'm a sucker for charts and figures. So purple earth occurred before the GOE, yes? If that's the case, then would earth's dull rocky landmasses be surrounded by a ring of purple shallows, with the oceans full of green iron sulfate? That would be a cool looking planet.

@GEOGIRL 11 ай бұрын

Haha yes, technically the land would've still been pretty bland, and earth would hardly have been fully purple. Rather it would've had the occasional purple 'bloom' or productivity lighting up the ocean's surface, but it still would've been so cool! ;D I imagine the Fe minerals would've been deeper rather than floating like planktonic blooms of phototrophs, so I would guess the purple was masking the green, but I could be wrong, especially since the ocean was probably not completely covered in these blooms. But idk, I am not sure how shallow the fe deposits would've come or if the more shallow regions would've been covered with carbonates like today (only abiotic instead of biotic ones). What an intriguing question! I will have to do more research ;)

@davidniemi6553 11 ай бұрын

@@GEOGIRL It seems to me this really emphasizes how complex it is to recognize life (or proto-life) on faraway planets. And even with we find it, there may be a lot of distance to anything that could lead to intelligent life. And if there is intelligent sulfur-based life, just how alien would it be to us?

@DavidLindes 11 ай бұрын

As a live-long lover of purple things, this is exciting to learn about. Great video; thanks!

@DavidLindes 11 ай бұрын

Oops, *life-long. Also: bunch of great content here. Subbed!

@ronaldbucchino1086 11 ай бұрын

Wonderful presentation -- I hate to say it, but you and your Earth Pillow are adorable -- and you are brilliantly creative. Please keep up the good work. Your current and future students are fortunate to learn from you. Thanks.

@kwimms 11 ай бұрын

She's a brilliant liar and fool... maybe she should get out of "science" and back to the kitchen ... recipes can be very creative.

@legoseanland1760 11 ай бұрын

New to you, delighted, subscribed

@JasonKale 11 ай бұрын

Always Enlightening Information!!! I would have never thought the Earth was once possibly Purple!!!

@GEOGIRL 11 ай бұрын

Thank you! So glad you enjoyed it and learned something new ;D

@JasonKale 11 ай бұрын

@@GEOGIRL I always learn something new!!! I found this vid particularly interesting.. I believe this would also pertain to astro biology when posing the question of life on other planets pertaining to another Stars emission spectrum and what that could mean for possible life..Maybe we should be looking for Purple planets??? lol

@FreeXenon 11 ай бұрын

Love your videos!

@GEOGIRL 11 ай бұрын

Thank you! So glad you enjoy my videos ;D

@michaeleisenberg7867 Жыл бұрын

Rachel, This video is the 💣! Tons of cell bio. Lipid bilayer. Membrane bound proteins. Retinal/rhodopsin vs. chlorophyll/PS1&2 💥. Red + blue = purple ✅.

@GEOGIRL Жыл бұрын

Thanks so much! I am so glad you enjoyed it ;D It is one of my all time favs for sure! I just love talking about microbes, especially ancient microbes ;)

@Dank_Lulu 11 ай бұрын

Fascinating...

@jaydaksrules5316 10 ай бұрын

Great video glad i found your channel 😍. Maybe the co2 levels had abit to do with the changes but the other thing certain light spectrums trigger growth characteristics in plants. In general, blue light spectrums encourage vegetative and structural growth and red light promotes flowering, fruit, leaf growth, and stem elongation.🤔

@transponderings 11 ай бұрын

An interesting excursion into a subject I know next to nothing about - thank you for enlightening me. One thing I’m slightly puzzled by at the moment (well, sort of two things): 1. Where did early retinal-based phototrophs get their organic carbon? (Which other organisms?) 2. Where did the first oxygenic photosynthesisers get their carbon dioxide?

@GEOGIRL 11 ай бұрын

Well the second is easiest, co2 was very abundant on early earth in both the atmosphere and oceans. The first question is less simple. The most simple answer is they got their org carbon from other early microbes, but what about the very first microbes? If we assume heterotrophs evolved first then where’d the first life get its organic carbon? Well there is actually organic carbon that is abiogenic (produced without needing life). These are not complex molecules, just simple amino acids, but none the less they are organic carbon that would’ve like fed the first heterotrophs on earth :) Also, like I mentioned in the video these early retinal guys might’ve been methanogens and thus could’ve gotten their carbon from methane :)

@transponderings 11 ай бұрын

Thank you,@@GEOGIRL, for your quick answer to my questions!

@jram7047 10 ай бұрын

This was really interesting. It seems like it could be an exciting field to work with if there are any examples of the older species left or able to be reproduced.

@calinradu1378 11 ай бұрын

Well yet another explanation why complex life evolved so late on Earth! Makes us wander if perhaps on other planets it could have met better conditions early on and evolved way earlier. So fascinating to imagine a Phanerozoic eon that is 2 billion years old or more instead of one just 540 million years old like it was the case on Earth!

@Daoland-Everywhere 11 ай бұрын

People also absorb solar energy, to make certain vitamine, enzymen etc. This helps us to energizer our system to make atp too

@joranbooth5529 11 ай бұрын

I always appreciate that you add the "how do we know" parts in more detail than other videos.

@GEOGIRL 11 ай бұрын

Thank you! I am so glad you appreciate that! Sometimes I wonder if I am sharing too much, like if there are certain unnecessary or boring details, but I just really like to make sure I share the whole story, so I am very glad you like that about my videos ;D

@joranbooth5529 11 ай бұрын

@@GEOGIRL Not at all. I find that there are tons of videos that do a high-level skim of the ideas, such as Eons. And those are fantastic videos, to be sure. But short of dry university lectures that happened to be caught on video, there is nearly no one giving additional detail. For a brief stint in grad school, when I was deconstructing my faith, I briefly embraced young-earth creationism precisely because the kinds of details you share were hard to access, leaving the door open to pseudo-scientists waving their hands and showing some niche examples that didn't fit the highest-level explanations. The details you share are extremely interesting to me. I LOVE it when you show graphs of it too. Too many STEM videos avoid the data or math to keep it accessible, but in doing so, they keep it appropriate for k-10. But I'm not going to take geology or biology courses at this point in my career, and I still want to learn this stuff, so your videos hit a very underserved segment in STEM science communication. Thanks!

@georgeb.wolffsohn30 11 ай бұрын

Adenosine Tri Phosphate. Thank You Mr. Morris for realizing that I could be paying attention despite having ZERO finished Labs and negligible notes.

@randomistough0 11 ай бұрын

nice google slides presentation. no seriously, I feel like this is a video I'd see at school and get nostalgic over years later

@ansfridaeyowulfsdottir8095 11 ай бұрын

Decades ago one of my lecturers in biophysics researched purple sulphur bacteria. Actually, they were probably purple non-sulphur bacteria, as he had a large hot room with demi-johns containing magnetic stirrers and this purple, cloudy stuff, with bright lights shining on them. It didn't look very anaerobic! Anyway, sulphur, non-sulphur, they were definitely purple! {:o:O:}

@GEOGIRL 11 ай бұрын

Oh so interesting! The paper I used for that part of the video suggested they were purple sulfur bacteria, but I am sure there are other hypotheses, and I am sure some hypothesize it was maybe a combination of both! I wish we could go back in time and look ;D

@DeanHelton-ki7ku 11 ай бұрын

Very interesting.

@AlEndo01 11 ай бұрын

I'm not sure of the reasoning behind chlorophyl-based photosynthesis evolving because earlier life forms did not use green light. There was an old joke about the cathedral in Munich: "Why does it have two clock towers?" Answer: " In case somebody is looking at the other clock." Did they somehow compete for photons?

@natwon633 11 ай бұрын

This video became incredibly important for my worldbuilding

@Nalisification 10 ай бұрын

I love telling people about the early Earth. The Great Oxygen Catastrophy being one of my favorite tales.

@martinchrist4483 3 ай бұрын

Comment about info at 5:50-- I'm not Geogirl so it may be wrong! Phototaxis is when a whole organism moves toward the light. Phototropism (just one h) is when something turns toward the light, like Helianthus, the sunflower, and phototrophy (2 h's) is something getting energy from light. I love your channel!!

@Hashtronomus 11 ай бұрын

A purple earth would be beautiful to see

@Petr75661 11 ай бұрын

we would have leafy purples in our salads and purplery in our gardens

@crackers0413 11 ай бұрын

I clicked on your video because I have the same periodic table in the background :)

@donaldbrizzolara7720 11 ай бұрын

Rachel: What if Earth wasn't the only planet that experienced this purple phase? What if this hypothesis might give us insight into potential life on exoplanets…and if the purple earth hypothesis is correct and there was a dominance of purple organisms in the early Earth, then might we be able to find another planet that's at an earlier stage of evolution of the planet, where the purple pigments might have dominated?

@kwimms 11 ай бұрын

Earth is not a planet. There are no planets, just round lights in the sky. We are down here... the sky is up there... the only thing purple is your brain. Get a new one.

@ericlopez1067 3 ай бұрын

Just came across this for the first time and this was fascinating. I'm an exoplanet atmosphere modeler but my office mate thinks about the Archean and I love trying to picture how incredibly bizarre Archean Earth must've looked. I've also heard it suggested that the skies would have been orange due to methane hazes, the land, such as there was, would've mostly been black due to the lack of oxidization or land based life, and the oceans might have been green due to all the dissolved unoxidized iron Is it right to imagine that the purple phototrophs would've mostly been in stromatolite colonies in shallow seas? So now basically I'm picturing a ocean world filled with green seas, dotted with black volcanic islands surrounded by purple lagoons, lit by orange smoggy skies?

@laletemanolete 11 ай бұрын

The way you explain is very good. Do you use a script?

@robinleow185 11 ай бұрын

Hi Rachel, it is nice of you to come up with this explanatory video on Purple Earth. It would be a sequel to the Pale Orange Dot Earth (3.8 to 2.5 Ga) - Source: NASA, in your Physical Geology Playlist: kzfaq.info/get/bejne/rbqVmsRnmJmYc6s.html . It reminds us that Earth does not look as it is now (blue and green) but has evolved through time.

@coweatsman 11 ай бұрын

Interesting about the eye absorbing light in retinal photosynthesis. The particular blue hue of the sky has a psychological effect on us giving us a feeling of well being. The lack of it for an extended time like winter periods gives some people today seasonal affective disorder (SAD) as an evolutionary adaptation. In the depths of winter in the ice age feeling like "seizing the day" and "making it all happen" by going outside in the freezing blizzard winds with no food, big game migrated away for the winter would likely mean a dead ice age man. Feeling like doing nothing is exactly the best strategy at such a time.

@glennchartrand5411 11 ай бұрын

Water absorbs lower frequencies of light faster than higher frequencies. (At 9 meters there is so little red light that blood appears to be blackish green because green and blue light are still available.) So chlorophyll's ability to absorb blue light would enable those organisms with it to undergo phototrophy at a deeper depth than the Retinol based organisms. And since the Retinol based organisms would view the Chlorophyll based organisms as "a source of organic carbon" that would come in very handy. Being able to absorb red light was just a convenient side effect because red just happens to be twice the wavelength of blue.

@m_sedziwoj 11 ай бұрын

10:30 this is interesting, because I heard different theory for this "inefficient" absorption of chlorophyll, and was on more popular channel, and was about overheating or something like this.

@AndrewMellor-darkphoton 11 ай бұрын

Do you know how they got the hydrogen gradient on the original purple ones. If I remember right modern photosynthesis goes chlorophyll lenses create electric current then proteins use the electric current to do electrolysis to create a hydrogen gradient then the hydrogen gradients used by proteins to recharge ATP then sugar is bombarded by ATP and CO2 to make more sugar. I got the impression the second purple ones used hydrogen sulfide electrolysis instead of water electrolysis for a hydrogen gradient. So I'm curious what the first purple ones used as a hydrogen source for the hydrogen gradient for ATP?

@GEOGIRL 11 ай бұрын

That's a great question! I had to do some searching because I kept finding things that just said "the bacteriorhodospin undergoes structural change when it absorbs light which causes it to pump protons in/out of the cell" and I just kept being like "But where is it getting the protons?!" haha I finally found that bacteriorhodopsin-based phototrophs, like haloarchaea, take up protons directly from the surrounding environment, typically very saline & acidic water. This doesn't take any energy because when in a very saline/acidic environment, the hydrogen ions will already naturally want to go where they are less concentrated (into the cell). However, the cell then needs to pump them out of the cell to create the gradient of more out than in which drives the ATP synthase protein and thus, ATP production. This pumping the protons out of the cell requires energy because it goes against the natural concentration gradient of protons, so they use the energy from the light that their pigment's absorb to do this. I hope that helps! ;D And thanks for asking that, that is such an important question!

@AndrewMellor-darkphoton 11 ай бұрын

@@GEOGIRL So they get it from natural hydronium that enters through osmosis then fight the hydronium with light? Do you know where the acid comes from? I'm guessing it could come from carbonic acid but since the water is pretty salty salt would probably come with minerals which would turn into carbonate. Were there low levels of carbonate back then?

@CaseiShirota. 11 ай бұрын

Amazing video, i was wondering why photosintethic organism was Green.

@GEOGIRL 11 ай бұрын

Thanks! I am so glad you enjoyed it :)

@sirwaldo999 11 ай бұрын

The more I hav learned about stromatolites, the more Im certain of my hypothesis about them being the origin of the rose rocks that are very common here In Oklahoma where I am from and live. When I saw what they look like when alive I thought, I hav definitely seen that pattern somewhere before and it is rose rocks. Stromatolites that lived in the shallow sea that once covered this part of the country are now our state rock

@roaldpage 10 ай бұрын

Chlorophyl maybe green but some plants change the spectrums they reflect vs absorb through other pigments such as anthocyanins, which can allow certain species of plants to become red, purple, or blue tinted.

@juliancarax4797 10 ай бұрын

wow its soo cool i never learned that in school

@wolfpackastrobiology3690 11 ай бұрын

In my opinion there are two problems with the hypothesis: 1. Chemical analysis of the oldest rocks shows that the atmosphere of the early Earth was very inert and there wouldn't have been an abundant source of organic carbon on the 3.7 Ga which makes it more likely that the first phototrophs were producing vs consuming organic carbon. 2. Although the retinol based pigments absorb more light on the surface you have to remember that the first organisms lived in water and one of the chlorophyll absorbance peaks is in the blue light range (the wavelengths that can penetrate the furthest in water). This is going to be even more important on the early Earth when the top mixing layer of the oceans would have been inundated with intense UV light.

@micaheaton4422 11 ай бұрын

You can see how the long chains for passing hydrogen along them allow for greater complexity of configuration. The purple stuff's energy generating mechanism has to operate close to the cell wall. Photosynthetic organisms may not have to operate under that restriction. The production of oxygen as a side benefit is more probable in something more complex. Evolution could be more successful if things like producing oxygen don't have to be the point of some focus. We need to give them room enough for them to be random, not possessed of some purpose. Then, once in place, the very idea of them becomes embedded. They remain, even if they amount to giving oxygen away, not reusing it somehow.

@ellenmcgowen 11 ай бұрын

There is an abiotic model for the oxygen producing step in photosynthesis: manganese + water + UV light splits water molecules and generates molecular oxygen. The key water-splitting enzyme in photosynthesis uses manganese as the catalyst. So it is possible that ancestors of photosynthetic cyanobacteria coopted this abiotic process to generate ATP and then later evolved the carbon-fixing reaction and the antenna complex. The antenna complex is the green bit (chlorophyll) so some water-splitting and oxygen generation could have been occurring while the Earth was still purple from bacterial rhodopsin. The (probably small) amount of oxygen produced in this early stage would have been buffered by the reduced environment.

@robertgaines-tulsa 11 ай бұрын

Sounds like a stinky Earth hypothesis with a purple-brown Earth.

@jonathanaarhus224 9 ай бұрын

It seems like animal life evolved from retinal based phototrophes because we still have retinals in our eyes, which may be a lagacy holdover from early evolution. If this is true, proto-animals switched over to resperation to take advantage of the oxygenation event. Perhaps study into mycology could shed light on this point, since fungi seem to resemble the hypothetical precursers to animal life.

@wespeakforthetrees 11 ай бұрын

I had no idea that the sulfur based life was so close in time. Thanks for the education.

@foxgloved8922 11 ай бұрын

On the topic of human phototrophy, does vitamin D synthesis count? Maybe this is covered later, I haven’t finished watching

@GEOGIRL 11 ай бұрын

Absolutely it does! ;D

@Chiavaccio 11 ай бұрын

Great!👏👏👏👍👍

@GEOGIRL 11 ай бұрын

Thank you! :D

@Chiavaccio 11 ай бұрын

@@GEOGIRL 👍👍👋😊

@rainaldkoch9093 10 ай бұрын

Under sunlight, green leafs are cooler than purple leafs, because the light spectrum peaks in the green region. High temperature would mean higher evaporation of water, lower efficiency of many pathways, and more to repair (consuming energy). That may explain why plants keep reflecting green light even though green-consuming retinol is much less abundant than it used to be.

@robertmoye7565 11 ай бұрын

Great video with clear explanations. Does the evolution of different photosynthetic strategies have any relationship to the brightening of solar radiation over time? Solar luminosity was about 30% less intense when the Earth formed and has increased over time. Did early photosynthetic mechanisms need to capture more of the spectrum due to this lower intensity? Was the rise of chlorophyll-based mechanisms possible because more energy was later available at the upper and lower portions of the visible spectrum?

@GEOGIRL 11 ай бұрын

That's a great question! Based on how early in Earth's history both bactiorhodopsin and chlorophyll pigments evolved, I don't think the intensity had changed much by that time and thus, it likely did not play a large role in the evolution/properties of these pigments. Moreover, the solar spectrum has not changed over time, only the solar intensity, so I am not sure that would've affected the spectral properties of such pigments even if they had evolved much later. Like you said, they might've evolved to absorb more of the solar spectrum when it was less intense, and that seems to be the case with bacteriorhodopsin seemingly absorbing the more intense regions, but I am not sure if that is causation or correlation ;) Interesting thought though! :)

@robertmoye7565 11 ай бұрын

@@GEOGIRL thank you for your thoughtful reply. It is an interesting subject. I was around the Geology Department of the University of Tasmania (Australia) ca. 2005-2012 and there was some interesting research on the changing chemistry of the oceans during the Boring Billion, which turns out to be not boring at all.

@GEOGIRL 11 ай бұрын

@@robertmoye7565 Agreed! The boring billion had some of the most interesting ocean chemistry ever! That is actually right up my research ally ;)

@rayceeya8659 10 ай бұрын

IIRC from my college biochem courses, oxygenic photosynthesis requires some free oxygen to get started. That's at least part of the reason anoxygenic photosynthesis started first.

@GEOGIRL 10 ай бұрын

Did oxygen photosynthesis need free oxygen to get started? Oxygenic photosynthesis is the photosynthetic production of free oxygen. Thus, oxygen is the product of this pathway, not the reactant. So, I am not sure it needed free oxygen to get started, but I could be wrong, there could certainly be very specific biochemical details I am unaware of :)

@rayceeya8659 10 ай бұрын

@@GEOGIRL I'm sorry, it's been a couple decades but like I said. If I recall correctly it takes a little bit of free oxygen to get it started. My information may be out of date because college was twenty years ago. But I'm pretty sure that at least one of the enzymes in the Calvin cycle needs free oxygen to form properly. Again this is from a lecture from twenty years ago so I may be out of date.

@TropicalCoder 11 ай бұрын

Fascinating. Always wondered why plants reflect reflect away the green part of the spectrum. So you say they choose a different part of the spectrum from the purple bacteria to be able to compete - by finding a different ecological niche, so to speak. But that is not so clear. It's not like purple bacteria use up all the purple in the world. Only makes sense if both kinds of bacteria are all bunched up together, literally living on top of each other and filtering the light that reaches those below. That is the implication of your theory. I would think each would stick to their own neighbourhood, where they are born, raised up, and die. In that case there is enough spectrum for all - at least until the plants killed off the purple bacteria by poisoning the atmosphere with oxygen.

@GEOGIRL 11 ай бұрын

Actually, it is for the exact reason you mention that this hypothesis is possible, it is that they did (and still do) live 'bunched up' or layered as you mention, in microbial mats! :) The green oxygenic phototrophs on top and the purple anoxygenic ones using the filtered light below. At least this is the case for oxygenic and anoxygenic photosynthesizers; I am not sure if it is also the case for the bacteriorhodspin-using phototrophs, but it is likely as the fossil record suggests that microbial mats were the major living 'behavior' of phototrophic microbes on this early earth :) But I wouldn't use the word 'choose' when explaining why green phototrophs evolved, but rather that this became the most beneficial and evolutionary advantageous trait (or pigment in this case) to have as a newly evolving phototroph in a world where you share space with the more primitive guys ;) Hope that makes more sense!

@TropicalCoder 11 ай бұрын

@@GEOGIRL Thanks for the clarification. An interesting analogy here are layered photocells for producing electricity from light. Each layer extracts energy from a different part of the spectrum, and allows the unused portion of the spectrum pass through to the layer beneath. In this manner they can max out the amount of energy that can be extracted from each square unit of surface.

@annekeener4119 11 ай бұрын

Retinol-based phototrophy will look familiar to anyone studying how eukaryotes break down sugar into ATP. The mitochondria probably once were free-living purple sulfur bacteria.