How & Why Earth Went From Purple to Green (Twice!) | GEO GIRL
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- čas přidán 22. 07. 2024
- 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
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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:
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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! - Věda a technologie
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! -> czcams.com/video/IIA-k_bBcL0/video.html
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.
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!
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? 😊
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.
Beg pardon, but humans DO photosynthesize! (~6:00) We make Vitamin D using sunlight.
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...
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 :)
"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.
Same experience. Some of the information on hydrogen sulfide bacteria was in a bio textbook we used but we barely mentioned it in class.
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 CZcams to spread the kind of high-quality content such as yours to the four corners of the world! 😃
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!
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!
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.
Earth 🌍 is not in a vacuum. . . Oh wait 😅
Dominion (2018)
@@Bostonceltics1369 My brain won't shut up lol.
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!
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
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.
@@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.
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!
Also our retina converts light into chemical energy and then into action potentials, which is also phototrophic!
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!
'Retinol' is the molecule
Dominion (2018)
Bilberry,puts the purple back in your eyes,OHH THE COLORS💜🤗💜😘👍
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.
Thank you so much! So glad you enjoy the videos :)
Fascinating as always, keep the good work up if you can!
so cool🦠💜🌎 great videos! thank you for all your time and efforts🍎
🙏🙏🙏🙏 incredibly interested in early life… and the immense volume of earth time…. Blows my tiny mind…🙏
🙏
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.
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!
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 !❤🎉
Finally the CZcams 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.
Thank you so much for the kind words! 😊
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!
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 😆
Thank you so much! I am so glad you enjoyed it, it is one of my favorites now as well :)
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~
Thanks so much! So glad you liked the deep dive ;)
Thank you for making this. Your channel is supes underrated. ^^
Thank you so much!
@@GEOGIRL You're most welcome :)
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
What an amazing communicator you are, you make everything so interesting!
Thank you so much! ;D
I just discovered your channel, and I really appreciate that you provide all your references. Many thanks to you!
Thank you! So glad you enjoy my content ;D
Brilliant video, new fan and checking out your others
this channel deserves way more subscribers!!
Just discovered this page & I immediately hit the subscribe button. Looking forward to watching all the videos, past & future. 🤗
Thanks so much! So glad you like my videos ;D
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!
I have learned a lot. Thanks!
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.
this is an amazing channel. the website linked is great too ! V glad the algorithm recommended this channel for me
Thanks so much! So glad you like my channel ;D
@@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 🙂
That was fascinating. Thank you
Both very interesting and explanatory!
Well done , ( This really needs to be included in school bio classes , big time)
Beautiful! Good Sunday!
Thank you! ;D
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.
This is what I have seen too. It’s a compromise - avoiding getting “sunburnt” as it were - from absorbing too much radiation.
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.
I had never heard of this before. It is interesting!
I love it when Jackson's chameleons change color, and now I can say the same about the Earth. 😊 ❤
I never had any special affinity towards geology, but I like this channel. Subbed!
New discovery about past earth history thank you geo girl excellent
Love your videos!
Thank you! So glad you enjoy my videos ;D
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.
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 CZcams video of all things! Anyways, keep up the good work! :D
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 😊
New to you, delighted, subscribed
That was back when Barney roamed the earth.
You rock!❤❤❤
Fascinating...
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.
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 ;)
@@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?
As a live-long lover of purple things, this is exciting to learn about. Great video; thanks!
Oops, *life-long.
Also: bunch of great content here. Subbed!
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?
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.. 👍👍👍
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
Always Enlightening Information!!! I would have never thought the Earth was once possibly Purple!!!
Thank you! So glad you enjoyed it and learned something new ;D
@@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
Rachel, This video is the 💣! Tons of cell bio. Lipid bilayer. Membrane bound proteins. Retinal/rhodopsin vs. chlorophyll/PS1&2 💥. Red + blue = purple ✅.
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 ;)
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. 😂
Really fascinating stuff! Thank you so much.⚗⚛🔬🌌☄
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?
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! :)
Very interesting.
I always appreciate that you add the "how do we know" parts in more detail than other videos.
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
@@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!
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
Me too
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.
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,
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?
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 :)
Thank you,@@GEOGIRL, for your quick answer to my questions!
No longer purplexed due to the light shed here.
This comment is just the best
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)
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!
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.
She's a brilliant liar and fool... maybe she should get out of "science" and back to the kitchen ... recipes can be very creative.
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?
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!
@@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?
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.
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.🤔
nice google slides presentation. no seriously, I feel like this is a video I'd see at school and get nostalgic over years later
I clicked on your video because I have the same periodic table in the background :)
Great!👏👏👏👍👍
Thank you! :D
@@GEOGIRL 👍👍👋😊
On the topic of human phototrophy, does vitamin D synthesis count? Maybe this is covered later, I haven’t finished watching
Absolutely it does! ;D
I love telling people about the early Earth. The Great Oxygen Catastrophy being one of my favorite tales.
People also absorb solar energy, to make certain vitamine, enzymen etc. This helps us to energizer our system to make atp too
Adenosine Tri Phosphate.
Thank You Mr. Morris for realizing that I could be paying attention despite having ZERO finished Labs and negligible notes.
The way you explain is very good. Do you use a script?
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?
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! :)
@@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.
@@robertmoye7565 Agreed! The boring billion had some of the most interesting ocean chemistry ever! That is actually right up my research ally ;)
12:25 dose solar spectrum change with time? Because Sun is not same as it was, but I don't know about light spectrum.
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?
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.
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.
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.
Amazing video, i was wondering why photosintethic organism was Green.
Thanks! I am so glad you enjoyed it :)
we would have leafy purples in our salads and purplery in our gardens
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!!
Is there any biosystem that photosyntheticly breaks SO4 into sulphur and oxygen,( *not* HS onto S and HSO4)
A purple earth would be beautiful to see
wow its soo cool i never learned that in school
Thanks doc (twice)
If retinal-based phototrophs evolved first (based on wavelength spectrum absorption) and photosynthetic organisms later, then where did retinal-based phototrophs get their organic carbon from?
Thank you
Great question! Before oxygenic photosynthesis evolved, there was already plenty of life, much of which was chemotrophic (got energy from chemicals rather than light), so the first phototrophs, whether they were these retinal based guys or something else, would've had plenty of org. carbon around :)
Thank you for your response! To clarify, are you suggesting that the sequence of events unfolded as follows: 4.1 billion years ago, the emergence of first chemotrophs (somewhere at oceanic floor next to hydrothermal vents); 3.7 billion years ago, the appearance of retinal-based phototrophs; and 3.5 billion years ago, the development of photosynthetic cyanobacteria, contributing to the formation of stromatolites?@@GEOGIRL
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?
I would love to know what programs you use to make these presentations?
Haha, I am pretty 'low tech' ;) I just use powerpoint for my lecture slides and zoom for recording :)
@GEOGIRL Thank you for replying, much appreciated. I'll look into Zoom
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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.
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!
@@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.
There are some purple colored trees (Crimson King Maple) and plants (Black Onyx pepper plants), are they absorbing more of the green sunlight?
This video became incredibly important for my worldbuilding
What color was the rain at that time?
hmm this makes me think about trees and plants with red/purple leaves.
is it normal photosyntesis but on another wave length ??
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?
Is it possible to compete for particular spectra of light? Like, plants clearly compete for light, but it's a bit of an all-or-nothing game, isn't it? The green spectrum light wasn't passing directly through the retinol-based lifeforms, was it? Or is the implication here that they reflected enough light to enable the chlorophylls?
Since the purple ones do not release oxygen, what good are they?
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.
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 :)
@@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.
I had no idea that the sulfur based life was so close in time. Thanks for the education.