This channel should have a millions of subscribers. Even a biology-oriented guy like me has to love this stuff! Why aren't more people wanting to take advantage of this free education?
Quote Biology oriented guy like me.. So you're simping for a chick in a video.. LoL Next, Start sending her All your money.. cha ching. 100s of channels just like this one on YT.
@@jesusisunstoppable4438 I'm probably older than this girl's father. I'm interested in learning, not creeping. And when so many UA-cam educators treat their audience like idiots I make sure to tell the ones who don't that they're appreciated.
Thank you for providing these lectures for free. Your presentation makes the topic accessible without feeling cursory. I can't believe how much work goes into them. I feel like I'm getting a college education over here.
Howdy Rachel, thanks for keeping this old fossil up to date. I didn’t realize how recent it’s been since the Ediacaran has been differentiated within the Precambrian. Back in my day it was Cambrian and Precambrian with suspected cellular to multicellular development without any evidence. I’ve been thinking about a field trip to the Manzanos mountains looking for the great unconformity of snowball earth. Hope I can recognize it.
Wow. The importance of water viscosity. There’s always something new and interesting in your videos. This does seem to make complex multicellular life less likely on other planets.
Raleigh number/relative viscosity gets really weird at small scales - thrips _(really_ small insects) have brush-like wings and almost swim through the air because it's soupy at their scale.
Depends on their history. There's a reasonable argument that every photosynthetic-life-bearing planet might go through such a stage: it starts out with a significant greenhouse effect but not so hot to be uninhabitable, photosynthesisers pull CO2 out of the atmosphere, the planet cools to freezing, and a new equilibrium arises coming out of the snowball phase (possibly aided by the star growing more luminous as it ages). It also arguably makes multicellular life in ice worlds with subsurface oceans more likely, unless life there is tightly clustered around warm spots like hydrothermal vents (which might well be the case since there'd be no photosynthesis there, but if there are nutrients to be found in colder regions, there might be multicellular life to exploit it). Although, to be fair, I'm sceptical that complex multicellular life could be supported without photosynthesis.
@@Draxynnic it makes an iceball moon like Europa all the more intriguing. With its core being constantly kneaded by Jupiter's gravity, liquid water down deep is certainly a possibility, complete with hydrothermal vents. Finding even simple multicellular life down there would be a real eye-opener.
THANK YOU THANK YOU THANIK YOU! I'm just starting the vid, but you liked my "WORM WARS" speculation last year (so did Scii Show), and now you're going in depth on the relevant time period, likely with the latest data. COOL! Sci Show responded to comment with an episode, but aimed at High School kids, as they do. This sounds like an updated take for undergrads, surveying recent scholarship. Yay! 🤗
I graduated BSc Geol. in 1977(!), the well of geological knowledge has expanded massively since then and your vid-docs fill the gaps in my understanding marvellously - excellent narration and graphics make it a really enjoyable experience. Thank you.
@@GEOGIRL: more than deserved and I'm one of many appreciative viewers expressing similar sentiments, you really have hit the mark with this video (and several others) 😊
That was really fascinating Rachel! The relationship of the Ediacaran biota with later, Cambrian fauna has puzzled me too! I am of the opinion that at least some of these earlier guys were related to hard-shelled and soft-bodied animals which came shortly after because I find it odd for all of them to just go without leaving anything behind and new ones to appear without any connection to the previous...but I'm not an expert on the matter... It would be great if you could do a video on the early evolution of chordates (as far as it is known so far) because it is pretty obvious that their last common ancestor with invertebrates lived in Precambrian times and the period of the separation and their oldest history are quite murky topics. Just imagine...it has been discovered that vertebrates are actually genetically closer to tunicates than to early chordates like Pikaia!
Thank you for making these short lectures! I studied biology years ago, but did not study the history of life then. Became very interested in the topic later though and currently can use this information in my work. Point being these represents recent understanding and is presented in a familiar format. I'll be honest, I don't have the patience to shift through loads of academic papers (unless I have to) so being able to get recent information without having to do that is appreciated :D
If that’s what you are looking for I recommend checking Aron Ra’s “systematic classification of life”. You can find the playlist on his channel. It’s a series of 50+ videos, each circa ten minutes long, on the various stages of life evolution in chronological order starting from unicellular life up until humans. It’s extremely well done insomuch it packs a lot of updated and accurate scientific info in a succinct and accessible format. Great resource: I have watched it several times because I wanted to have a better understanding of evolution and, ngl, with such good videos available I have become too lazy to read books.😁
I grew up in the Rockies, in Utah, there are some rock outcroppings with beautiful jellyfish fossils. Have a few little ones. Wish I knew who to talk to get them looked at. Would walk along the side of the road, and kick over rocks, and find them. About the size of a quarter.
Oh my favorite paleo subject matter! Ediacaran life! Most researchers consider them to be animals, perhaps having primitive versions of the Hox genes. A minority of researchers such as Retallack believe they might have been some kind of even more primitive ancestors, somewhere at the root of animals and fungi. After all, both branches share many genes and are able to produce chitin, ergosterol and other compounds. Personally I think our interpretation of Dickinsonia might be slightly incorrect. Maybe Dickinsonia was not laying flat for feeding, but was floating vertically in water, right over the microbial mats. Most quilted ediacaran organisms were stemmed organisms feeding by filtration. What if all quilted organisms were feeding the same way, and none was living as a flat disc on the microbial mat.
I am not sure, but a quick google scholar search suggests that gamete reproduction evolved over a billion years ago in early algal species, so in algae, it was likely before snowball earth... But in animals (or animal ancestors) it may have coincided (as I am assuming sexual reproduction evolved more than once in separate lineages), but I am not sure! I hope somebody who knows more than me will respond to this thread! ;)
Thank you so much for doing such amazing, high quality, entertaining and educational content. I really like the energy on which you explain stuff. How lucky must be the people that have you as their teacher.
Thank you so much for the kind words! I love getting comments like this, I feel like I should send these to my students so they come to class more 😂 ;)
It's so mind blowing that eukaryotic cells first came about 2.7BYA, and not until 600MYA did multicellularity arise. In just 600MY of multicellularity the world has got everything from bacteria to highly intelligent primates who are capable of making and sharing videos describing the actual history of our evolutionary origins. (Sorry if any of those numbers are off. I haven't checked them in a while.) BY THE WAY. I was just talking about how crocks and birds had a common ancestor, and crocks did not evolve from dinosaurs, BUT my zoology lab manual, published this year, I think, says that yes, crocodilians DID evolve FROM dinosaurs. Has anyone else heard this anywhere?
Some sources I've seen suggests that multicellularity may have been as early as 900MYA, but that's disputed... and doesn't really change your point much. I'd put a big "citation needed" on your lab manual. I haven't seen that idea anywhere - everything I've seen has been pretty solid on pseudosuchians (crocodiles and extinct relatives) and panaves (pterosaurs and dinosaurs) being the two big archosaur groups. There are some Triassic pseudosuchians with similar morphologies to later dinosaur groups, though, which might have caused the confusion. Or maybe it's just a part of the manual that hasn't been updated in a long time.
Eccellent topic Rachel, thank you. I remain curious about when chemistry on Earth first became biology - I have watched a couple of Nick Lane presentations recently, and think he must be on the right track. Will we ever know how life began? Look forward to your weekly content - hope you keep it going.
It will be incredibly difficult to determine this, especially as we really still don't have a universally accepted definition of "life". Whatever happened did so over a period of millions of years and most likely involved at least one extremely unlikely event. There were most likely self-replicating short peptide strands experiencing something akin to selection pressures before RNA or membranes or metabolism. Was that life?
Nick Lane is such a good communicator! You should check his book, "The Vital Question". He is the most vocal proponent of the "metabolism first" hypothesis for the origin of life, which was first proposed by Wächtershäuser and postulates that life first arose in alkaline hydrothermal vents. If you like this topic, you should also read about the other leading hypothesis, which is the "primordial soup" hypothesis for the origin of life. Prof. David Deamer has written a few books on this topic.
Thanks so much! Also, I love Nick Lane!! ;D Such an inspiring science communicator :) His book about oxygen is my FAV (mainly because that was my field of research as a grad student haha) but I highly recommend for anyone who wants to better understand oxygen! ;D
Absolutely loved your video - liked and subscribed! Didn't like the term "evolutionary experiment" - there are no experiments in an unthinking system - would "failed evolutionary line" be better? 😊
That is a great point! I actually didn't coin the term, I have seen it used to describe the Ediacaran biota in literature, but your reasoning makes a lot of sense, I feel like failed evolutionary line is probably better ;)
@@GEOGIRL Thanks for the acknowledgment. I think that means I get 10% every time someone uses the phrase "failed evolutionary line". I'll be keeping tabs ;)
It is estimated based on genetic studies that Animals (Metazoa) appeared 900-750 Ma in Tonian (before Snowball Earth). The last common ancestor of Opisthokonts (Animals, Fungi, and related organisms) lived approx. 1.1-1.3 Ba.
Rhodophyta (red algae) were probably first multicellular organisms. They appeared before 1.0-1.2 Ba (billion years ago), it is possible that they might be already at 1.6 Ba. On other side, animals, fungi, green algae (including ancestors of plants) maybe had advantage in Snowball Earth conditions. In addition, everchanging conditions (glaciation, no ice, glaciation) might also speed up evolution, by forcing organisms to adapt to new conditions. It might be interesting to you that the last common ancestor of Opisthokonts (Animals, Fungi, and related organisms) lived approx. 1.1-1.3 Ba.
That is called an anomalocarid! These were some of the very first animal predators! I actually have a whole video about them because they were super cool :D you can check it out here if you want -> ua-cam.com/video/my2Ro4iP9pk/v-deo.htmlsi=KHC3oaFhmbLWOmTs
Really, all of the biosphere's history is the story of microbes. How they started out and formed larger and larger groups, until they united to create larger entities beings that could out-compete their less-coordinated rivals for resources.
I was so happy to see this video. I had guessed that multicellularity evolved during snowball Earth. My main reason for thinking that was how closely the Cambrian followed the thawing of the planet. There had been something going on under all that ice which took full advantage of the new ecological niches as they opened up. And, apparently, both plants and animals hit upon the same survival strategy: multicellular organisms. Quite the coincidence. Anyway, great video. Thank-you.
Four times higher viscosity sounds like a lot, but to put it to perspective, at room temperature dark ale has it ~2.5x higher than water already. Things like oils are orders of magnitude away, freezing water around 2x. So it'd probably be hardly perceptible to us, but at small scales ...
Geology ROCKS. 😍it's so deep. it can be moving, even if (shame!) only deep underneath... we live in a beautiful world. but under the surface, there was a whole lot that led us there! most of which may be surprisingly only a stone's throw away... but some that are clearly not for the stone age philosopher. 😼we've went through peaks and valleys over the eons, but all of them were crucial to a pretty wonderful equilibrium we could agree! i know the thought may leave you ice cold, but earth was not ALWAYS such a warm-- well, hot yes- place to be! if you look under a microscope, you may see innumerable signs of a long and chaotic, shifting history... the evidence is quite crystal-clear. absolutely rock-hard, iron-core! no matter what we may perceive through our own human eyes, even the most brutal of events had its part. from the very simplest volcanic eruptions, to the formation of attitude-defying peaks, or cosmic impacts that led to our Moon's origins... let us dig deeper! 😍.
Hmmm, I might need to also write a song about the pre-Cambrian Explosion. Good stuff. If you get a moment, check out my song, “Cambrian Explosion” by Paul Keller. Also, the book you recommended, Alien Oceans, was fantastic. Cheers! Paul
I think life in the Proterozoic might have been a bit less strictly microbial than we often say. The Snowball probably created the kind of power vacuum needed to allow previously obscure groups like animals and such to dominate. But just because animals weren't doing much complex stuff before that doesn't mean nothing was.
I wonder if the first undifferentiated multicellular species were capable of switching back and forth between unicellularism and multicellularism as conditions required.
Rhodophyta (red algae) were probably first multicellular organisms. They appeared before 1.0 Ba (billion years ago), it is possible that they might be 1.6 Ba. Rhodophyta are related to plants.
Awesome. Really well summarized. I have always (well, as long as we have known about it, which isn’t long) been fascinated by the Ediacaran biota. It seems increasingly that the consensus is that there is less of a connection to the Cambrian, at least than it once was assumed. But then how did the Cambrian life evolve so significantly - it couldn’t have appeared from single celled organisms to trilobites in a million years. So where are their progenitors? Such an interesting puzzle.
Ediacaran is one of my favorite periods (so is Cambrian), thank you for this! There's never enough scientific talk about very early life in my opinion. How much do we know of pre- and eucaryotic things? I only know about the stromatolites and other such microbial mats, is there more?
Yes, the saline leftover water became more viscous, but due to the cold temperatures not the salt content (because viscosity is temperature dependent: any liquid that gets colder gets more viscous and any liquid that gets hotter gets less viscous). It would've happened with or without the salt. ;)
This may be somewhat superficial reasoning, but I get the impression that the reason the Cambrian is defined as a distinct period from its preceding time is the sudden appearance of a multitude of animal hard parts. It seems unlikely that the first multicellular animals (ignoring those early porifera) to evolve would emerge immediately with such hard parts in place. Therefore they must have evolved from earlier species with mostly or fully soft bodies. This, by definition, would make these predecessors pre-Cambrian, and so Ediacaran. If the Cambrian fauna evolved from Ediacaran biota, and we've found a variety of soft-bodied lifeforms from that time, then what are the odds that the soft-bodied ancestors of the Cambrian fauna would remain undetected, while the known Ediacaran species would only be failed experiments and evolutionary dead ends? Conclusion: we need to think more imaginatively about how some of the Ediacaran critters gave rise to their Cambrian descendents. While also keeping a lookout for intermediate forms around the E-C boundary. Yes?/No?
Rachel ⚡, In your geology 💎 drip you are the bomb 💣! This is a fantastic video. Connects a lot of dots. One trap people might fall into is thinking there's a discreet end of the Ediacaran and beginning of the Cambrian. Sort of like act one, intermission, and act two. Nothing could be further from the truth. It's a gradual transition. I believe these time periods and epochs are somewhat arbitrary. Therefore, I believe there is a gradual transition or evolution from the Ediacaran to the early Cambrian animals. It's just we can't find them yet.
This is true! And a great point! There is a discrete a transition from the Ediacaran to Cambrian when it comes to periods on the timescale, but biological evolution does not work that way, it was certainly a gradual evolution of new traits that eventually took over in what we arbitrarily deem as the Cambrian period, I think that is so important to note, thank you for saying that! I think people often get the wrong idea from the term 'explosion' ;)
@@GEOGIRL Rachel 🛶! I think this might be another excellent video. Explaining which fossils disappeared between each period on the timescale; and how many years do the experts allow for transition between periods? Can they narrow it down to one year, one century, one million years? Thanks! Merch!
@@michaeleisenberg7867 There's actually a misconception that the so called "Cambrian explosion" somehow is an evidence against gradualism. Actually, it looks like that because we have a loss of strata in the geological record, which, in some regions of the world, comprises many millions of years, during the Neoproterozoic Era. This is the reason why it is expected that we don't find the direct ancestors to all Cambrian phyla, even though we have actually found a few in the late Ediacaran, like the ancestors of bivalves and porifera
Periods are often bookended with extinctions, and I think I have seen evidence that there might have been one towards the end of the Ediacaran - something to do with something evolving that destroyed the Ediacaran microbial mats thereby completely upending the ecosystem. Something also seems to have made having "hard parts" particularly important around then that several phyla developed them at once. But yes, it's pretty much guaranteed that all the Cambrian phyla had some non-mineralised late Ediacaran precursor. The only question is whether we've found those fossils or whether the similarities in appearance are convergent evolution. And on the other side of the equation, it's possible that some of the 'uniquely Ediacaran' biota did survive into the Palaeozoic, but wasn't preserved.
Hello mam I am pursuing my msc in geology from India but i had different interest for archaeology. Can you guide me whether these two fields can be combined.
Geo-Girl, always provocative and interesting. When I was a geology student at MSU, Montana, the Ediacara was as enigmatic like Planet X. Where are the cryptozooic conodonts is this history?
Hmm, interesting, food for thought. The early bit mentioned 'decomposition'; were there bacteria around to utilise or generate the decomposition, in which case, were they part of a symbiotic relationship like mammals and gut-biome? Did they evolve in tandem with the proto life-forms, or were they part of them, like seaweed/algae etc. Just trying to dot the I's, cross the T's and fill the gaps.🤔🙂
I was wondering what Snowball Earth was like. I imagine that over the continents, ice sheets were several kilometers thick, but over the ocean, the ice is much thinner. I was wondering if tides would break up the ice, leaving areas of frazil between ice floes. Which got me thinking, are there significant tides at the poles? Are tidal forces greater at the equator that at he poles? Maybe in conditions of Snowball Earth tidal forces would keep oceanic ice sheets broken up at the equator.
" Are tidal forces greater at the equator that at he poles?" The FORCES not greatly. The EFFECTS on the other hand do vary but not pole to equator. With the current distribution of continents the tidal variation is lower near the poles . Continental arrangement and varying ocean depths amplify and mutes the range of ocean tidal water sloshing and flows due to lunar influence. The common bulge illustration is not rubbish exactly but more an idealised smooth surface deep water world without significant disturbance of tidal force influence. It shows the cyclical nature but not representative of magnitude anywhere. Some areas of equatorial ocean have very low tidal variation, similar to polar areas, but 1,000 km away there is large variation. Central North Atlantic has low range, European coast has high range. "Maybe in conditions of Snowball Earth tidal forces would keep oceanic ice sheets broken up at the equator" Possibly. Depending on continental arrangements and ice sheet thickness, depth of oceans under the sheets and tidal flows under them.
If it's true that Snowball Earth triggered multicellularity then without that event Earth today would be the same as it'd always been: single celled life and that's all.
Won't it be great if We could travel back to before the Cambrian period, take DNA samples from the multicellular life forms from back then and then travel to the Cambrian period to take DNA samples from those life forms and then go back to the 21st Century to do a DNA comparison?
It's likely since cyanobacteria lived in microbial mats (layers of different microbial communities that provided each other nutrients), they didn't have the same degree of difficulty as other microbial organisms that didn't live in community mats because these mats are essentially multicellular organisms (even though they are made up of single-celled organisms) since their communities of microbes mutually benefit each other by providing each other nutrients :)
Did snowball Earth force animal evolution? That's like asking is the Pope catholic, it's a sure bet that that climatic effect had a profound influence on animal evolution.
I’d like to propose the coining of a new term: “discovery bias”. I think (more in the past than now) people have not considered different types of life, or body plans, or well, anything, because we can’t find them with their inability to fossilize.
It would be very interesting to trace flora mtDNA vs fawna mtDNA ancestry to see where the closest relationship is. While it's possible that (thinking)fawna mtDNA evolved as parallel evolution in separate instances from flora mtDNA, it seems much more likely that generally fawna's mtDNA followed host eukaryotic DNA conception bottle necks and has a broadly similar family tree to eukaryotic host DNA. If so, it's another strong hint that consciousness of fawna is inextricably entwined with mtDNA. And nothing else is physically closer to our eukaryotic host neural networks. Conveniently in "The whispering mitochondria - youtube", mitochondria have been found to communicate with each other. As with inventions, it takes a certain level of public new knowlege to promote seed ideas to inventors for parallel development of new inventions. With consciousness, we are now familiar with the concepts of fungal maze solving, massivly parallel computing, distributed intelligence, neurons, axons, dendrites, communicating mitochondria, conception, passing of mitochondria through the mother's egg and we have all the hints, mitochondria are a part of consciousness in all of earth's conscious species. Not only that, but they are well placed to pass the data component of instincts through their intact cells across the data bottleneck of conception. Every one of us is a "Noa's ark" of mitochondria carried in a eukaryotic host. The mitochondria have not coevolved through the millenia to be powerless in their host transactions, the co-dependence and synergy is total.
We will get more stranger early finds. I'm convinced we will get some big finds. Life before oxygen proliferation, may have had to do some strange things.
Ediacaran biota looks like animal plants! They look like plants, but they are actually animals! Aren't stromatolite mats multicellular? And, aren't the Cnidarians and Ediacaran similar to Stromatolite?
Stromatolites are just mats (or stacked layers) of single-celled microbial communities ;) So, they contain multiple cells, but are made up up unicellular organisms. I think you may be thinking of stromatoporoids, which are an ancient reef-building organism that is extinct now; these were potentially more closely related to phyla like porifera (sponges) and cnidaria (corals). :)
@@GEOGIRL I'm re-reading Horace Judson's "Eighth Day of Creation" to re-find a quote. I went through a blog of mine to put all the quotes into one ebook, and I've lost track of this one quote. Well, I found this one remark from James Watson(of DNA fame), He said that one should be at least partially unemployed to do great things. I thought this was interesting in light of a conversation we had about getting a Phd, and doing Phd research. That doing research under Phd, or even being a Phd and being paid for research for a certain amount of time is to restrictive. Wel, I thought this was interesting as confirming my feelings about it. I could not have made my book on a one or two year paid leave program for being a Phd!
In the book The Sixth Extinction, the author states that conditions on Earth have been beneficial for complex multicellular life for 750 million years, and these conditions will disappear in 750 million years. So, intelligent life emerged exactly in the middle of that period. That leaves us a lot of time to figure out future climate changes, what we can and cannot do to keep life going, and how we can (and should) save our ecosystems and carry them with us if we move away from Earth someday.
The 'braided stream' is the current model of evolution and yes this is more common than not. Humans did this, for instance, as we reabsorbed outlier groups like neanderthal and denisivand.
Observing bacterial, fungi colonies is easy to imagine they jumping to this state by having open enviroment insted of petri dish and no predators! I bet the salinity and stable (low entropy) and crystal like (hard shells) jump all bacteria into multi cellular system's
I really appreciate these sunday morning talks. Today's was no exception. I will say, I don't think of it as our animal origins, I think of it as our DNA origins. Maybe it's just two ways of saying the samething. Other than that, I was pretty much lost as usual. I think I'll get geology for dumby's and start from there. Lol 😆 Peace and Ahev
This channel should have a millions of subscribers. Even a biology-oriented guy like me has to love this stuff! Why aren't more people wanting to take advantage of this free education?
Her agw videos spook people
"Orientation?"
"Biology."
"Sex?"
"Only after the first billion years or so."
Quote
Biology oriented guy like me..
So you're simping for a chick in a video.. LoL
Next, Start sending her All your money.. cha ching.
100s of channels just like this one on YT.
@@jesusisunstoppable4438 I'm old enough to be this girl's dad, numbnuts lol
@@jesusisunstoppable4438 I'm probably older than this girl's father. I'm interested in learning, not creeping. And when so many UA-cam educators treat their audience like idiots I make sure to tell the ones who don't that they're appreciated.
Thank you for providing these lectures for free. Your presentation makes the topic accessible without feeling cursory. I can't believe how much work goes into them. I feel like I'm getting a college education over here.
Howdy Rachel, thanks for keeping this old fossil up to date. I didn’t realize how recent it’s been since the Ediacaran has been differentiated within the Precambrian. Back in my day it was Cambrian and Precambrian with suspected cellular to multicellular development without any evidence.
I’ve been thinking about a field trip to the Manzanos mountains looking for the great unconformity of snowball earth. Hope I can recognize it.
That's why I don't remember 'Ediacaran' era from school either. It didn't exist in early 2000's
criminally underrated channel
Thank you so much! You are too kind :)
Wow. The importance of water viscosity. There’s always something new and interesting in your videos. This does seem to make complex multicellular life less likely on other planets.
Raleigh number/relative viscosity gets really weird at small scales - thrips _(really_ small insects) have brush-like wings and almost swim through the air because it's soupy at their scale.
Depends on their history. There's a reasonable argument that every photosynthetic-life-bearing planet might go through such a stage: it starts out with a significant greenhouse effect but not so hot to be uninhabitable, photosynthesisers pull CO2 out of the atmosphere, the planet cools to freezing, and a new equilibrium arises coming out of the snowball phase (possibly aided by the star growing more luminous as it ages).
It also arguably makes multicellular life in ice worlds with subsurface oceans more likely, unless life there is tightly clustered around warm spots like hydrothermal vents (which might well be the case since there'd be no photosynthesis there, but if there are nutrients to be found in colder regions, there might be multicellular life to exploit it). Although, to be fair, I'm sceptical that complex multicellular life could be supported without photosynthesis.
@@williamchamberlain2263 I am an awe watching cilia constantly beating in water - there must be so much energy involved.
@@Draxynnic it makes an iceball moon like Europa all the more intriguing. With its core being constantly kneaded by Jupiter's gravity, liquid water down deep is certainly a possibility, complete with hydrothermal vents. Finding even simple multicellular life down there would be a real eye-opener.
THANK YOU THANK YOU THANIK YOU! I'm just starting the vid, but you liked my "WORM WARS" speculation last year (so did Scii Show), and now you're going in depth on the relevant time period, likely with the latest data. COOL! Sci Show responded to comment with an episode, but aimed at High School kids, as they do. This sounds like an updated take for undergrads, surveying recent scholarship. Yay! 🤗
I graduated BSc Geol. in 1977(!), the well of geological knowledge has expanded massively since then and your vid-docs fill the gaps in my understanding marvellously - excellent narration and graphics make it a really enjoyable experience. Thank you.
Thank you so much! That means a lot ;D
@@GEOGIRL: more than deserved and I'm one of many appreciative viewers expressing similar sentiments, you really have hit the mark with this video (and several others) 😊
THANK YOU! The Ediacaran is earth's most fascinating time period and there's so much more to discover.
So true! The Precambrian as a whole is my fav because of all that we still don't know yet!! ;D
Snowball Earth and the earliest multicellular entities is such a good topic. ✨😊✨
I love how this channel mixes geology with biology. It's all connected.
That was really fascinating Rachel! The relationship of the Ediacaran biota with later, Cambrian fauna has puzzled me too! I am of the opinion that at least some of these earlier guys were related to hard-shelled and soft-bodied animals which came shortly after because I find it odd for all of them to just go without leaving anything behind and new ones to appear without any connection to the previous...but I'm not an expert on the matter...
It would be great if you could do a video on the early evolution of chordates (as far as it is known so far) because it is pretty obvious that their last common ancestor with invertebrates lived in Precambrian times and the period of the separation and their oldest history are quite murky topics. Just imagine...it has been discovered that vertebrates are actually genetically closer to tunicates than to early chordates like Pikaia!
Thanks! Another topical video that increases my knowledge of what we know or think we know about the origin of life on earth. Thank you Dr. Phillips.
Thanks so much! ;D I am so glad you enjoyed it and learned something new :)
No way. I just wrote a 4000 word essay on this and this video would've been so helpful
Thank you for making these short lectures! I studied biology years ago, but did not study the history of life then. Became very interested in the topic later though and currently can use this information in my work. Point being these represents recent understanding and is presented in a familiar format. I'll be honest, I don't have the patience to shift through loads of academic papers (unless I have to) so being able to get recent information without having to do that is appreciated :D
If that’s what you are looking for I recommend checking Aron Ra’s “systematic classification of life”. You can find the playlist on his channel.
It’s a series of 50+ videos, each circa ten minutes long, on the various stages of life evolution in chronological order starting from unicellular life up until humans. It’s extremely well done insomuch it packs a lot of updated and accurate scientific info in a succinct and accessible format. Great resource: I have watched it several times because I wanted to have a better understanding of evolution and, ngl, with such good videos available I have become too lazy to read books.😁
Thank you Dr geo girl another excellent video
I grew up in the Rockies, in Utah, there are some rock outcroppings with beautiful jellyfish fossils. Have a few little ones. Wish I knew who to talk to get them looked at. Would walk along the side of the road, and kick over rocks, and find them. About the size of a quarter.
Oh my favorite paleo subject matter! Ediacaran life! Most researchers consider them to be animals, perhaps having primitive versions of the Hox genes. A minority of researchers such as Retallack believe they might have been some kind of even more primitive ancestors, somewhere at the root of animals and fungi. After all, both branches share many genes and are able to produce chitin, ergosterol and other compounds. Personally I think our interpretation of Dickinsonia might be slightly incorrect. Maybe Dickinsonia was not laying flat for feeding, but was floating vertically in water, right over the microbial mats. Most quilted ediacaran organisms were stemmed organisms feeding by filtration. What if all quilted organisms were feeding the same way, and none was living as a flat disc on the microbial mat.
Engaging presentation - good flow!
That would be so cool to walk across the oceans of snowball Earth -- with a winter hat, coat and snowboots of course!
I love this! i am a Nigerian cnidarian.
Excellant graphics, as always. Facinating and fun topic. Was the appearance of multicellularity concurrent with the appearance of gamete reproduction?
I am not sure, but a quick google scholar search suggests that gamete reproduction evolved over a billion years ago in early algal species, so in algae, it was likely before snowball earth... But in animals (or animal ancestors) it may have coincided (as I am assuming sexual reproduction evolved more than once in separate lineages), but I am not sure! I hope somebody who knows more than me will respond to this thread! ;)
Thank you so much for doing such amazing, high quality, entertaining and educational content.
I really like the energy on which you explain stuff. How lucky must be the people that have you as their teacher.
Thank you so much for the kind words! I love getting comments like this, I feel like I should send these to my students so they come to class more 😂 ;)
It's so mind blowing that eukaryotic cells first came about 2.7BYA, and not until 600MYA did multicellularity arise. In just 600MY of multicellularity the world has got everything from bacteria to highly intelligent primates who are capable of making and sharing videos describing the actual history of our evolutionary origins. (Sorry if any of those numbers are off. I haven't checked them in a while.)
BY THE WAY. I was just talking about how crocks and birds had a common ancestor, and crocks did not evolve from dinosaurs, BUT my zoology lab manual, published this year, I think, says that yes, crocodilians DID evolve FROM dinosaurs. Has anyone else heard this anywhere?
Some sources I've seen suggests that multicellularity may have been as early as 900MYA, but that's disputed... and doesn't really change your point much.
I'd put a big "citation needed" on your lab manual. I haven't seen that idea anywhere - everything I've seen has been pretty solid on pseudosuchians (crocodiles and extinct relatives) and panaves (pterosaurs and dinosaurs) being the two big archosaur groups. There are some Triassic pseudosuchians with similar morphologies to later dinosaur groups, though, which might have caused the confusion. Or maybe it's just a part of the manual that hasn't been updated in a long time.
@@Draxynnic That's exactly what I said to my zo prof!
Eccellent topic Rachel, thank you. I remain curious about when chemistry on Earth first became biology - I have watched a couple of Nick Lane presentations recently, and think he must be on the right track. Will we ever know how life began? Look forward to your weekly content - hope you keep it going.
It will be incredibly difficult to determine this, especially as we really still don't have a universally accepted definition of "life". Whatever happened did so over a period of millions of years and most likely involved at least one extremely unlikely event. There were most likely self-replicating short peptide strands experiencing something akin to selection pressures before RNA or membranes or metabolism. Was that life?
Nick Lane is such a good communicator! You should check his book, "The Vital Question". He is the most vocal proponent of the "metabolism first" hypothesis for the origin of life, which was first proposed by Wächtershäuser and postulates that life first arose in alkaline hydrothermal vents.
If you like this topic, you should also read about the other leading hypothesis, which is the "primordial soup" hypothesis for the origin of life.
Prof. David Deamer has written a few books on this topic.
Thanks so much! Also, I love Nick Lane!! ;D Such an inspiring science communicator :) His book about oxygen is my FAV (mainly because that was my field of research as a grad student haha) but I highly recommend for anyone who wants to better understand oxygen! ;D
Absolutely loved your video - liked and subscribed! Didn't like the term "evolutionary experiment" - there are no experiments in an unthinking system - would "failed evolutionary line" be better? 😊
That is a great point! I actually didn't coin the term, I have seen it used to describe the Ediacaran biota in literature, but your reasoning makes a lot of sense, I feel like failed evolutionary line is probably better ;)
@@GEOGIRL Thanks for the acknowledgment. I think that means I get 10% every time someone uses the phrase "failed evolutionary line". I'll be keeping tabs ;)
It is estimated based on genetic studies that Animals (Metazoa) appeared 900-750 Ma in Tonian (before Snowball Earth).
The last common ancestor of Opisthokonts (Animals, Fungi, and related organisms) lived approx. 1.1-1.3 Ba.
One of the most interesting periods in earth's history. Thank you so much for this video.
Of course! I couldn't agree more ;)
Rhodophyta (red algae) were probably first multicellular organisms. They appeared before 1.0-1.2 Ba (billion years ago), it is possible that they might be already at 1.6 Ba.
On other side, animals, fungi, green algae (including ancestors of plants) maybe had advantage in Snowball Earth conditions. In addition, everchanging conditions (glaciation, no ice, glaciation) might also speed up evolution, by forcing organisms to adapt to new conditions.
It might be interesting to you that the last common ancestor of Opisthokonts (Animals, Fungi, and related organisms) lived approx. 1.1-1.3 Ba.
Can't tell you how much I enjoy your videos. Except I just did.
I love how detailed this show is❤️❤️❤️
Wow. Great ideas. Thank you. 😊
Of course! So glad you enjoyed it ;D
At 12:00, in the painting on the right, what is that big weird critter that looks like a fish with 5 eyes... labelled Arthropoda?
That is called an anomalocarid! These were some of the very first animal predators! I actually have a whole video about them because they were super cool :D you can check it out here if you want -> ua-cam.com/video/my2Ro4iP9pk/v-deo.htmlsi=KHC3oaFhmbLWOmTs
@@GEOGIRL Thank you!
Really, all of the biosphere's history is the story of microbes. How they started out and formed larger and larger groups, until they united to create larger entities beings that could out-compete their less-coordinated rivals for resources.
What a awesome video! You rock! lol
Amazing video👏👍
fantastically fascinating! tyvm Doc.
I was so happy to see this video. I had guessed that multicellularity evolved during snowball Earth. My main reason for thinking that was how closely the Cambrian followed the thawing of the planet.
There had been something going on under all that ice which took full advantage of the new ecological niches as they opened up. And, apparently, both plants and animals hit upon the same survival strategy: multicellular organisms. Quite the coincidence.
Anyway, great video. Thank-you.
Four times higher viscosity sounds like a lot, but to put it to perspective, at room temperature dark ale has it ~2.5x higher than water already. Things like oils are orders of magnitude away, freezing water around 2x. So it'd probably be hardly perceptible to us, but at small scales ...
Thanks.... I was waiting for this video.
Geology ROCKS. 😍it's so deep. it can be moving, even if (shame!) only deep underneath... we live in a beautiful world. but under the surface, there was a whole lot that led us there! most of which may be surprisingly only a stone's throw away... but some that are clearly not for the stone age philosopher. 😼we've went through peaks and valleys over the eons, but all of them were crucial to a pretty wonderful equilibrium we could agree! i know the thought may leave you ice cold, but earth was not ALWAYS such a warm-- well, hot yes- place to be! if you look under a microscope, you may see innumerable signs of a long and chaotic, shifting history... the evidence is quite crystal-clear. absolutely rock-hard, iron-core! no matter what we may perceive through our own human eyes, even the most brutal of events had its part. from the very simplest volcanic eruptions, to the formation of attitude-defying peaks, or cosmic impacts that led to our Moon's origins... let us dig deeper! 😍.
great video, thanks
Cicada's. that's what.
Common Descent just did a whole podcast on cicadas 👍
Did you know you can mensure bacterial species entropy level? By the influence they have on water temperature variations?
Hmmm, I might need to also write a song about the pre-Cambrian Explosion. Good stuff. If you get a moment, check out my song, “Cambrian Explosion” by Paul Keller. Also, the book you recommended, Alien Oceans, was fantastic. Cheers! Paul
Amazing content! Subbed 🔥
Thanks so much! ;D
I think life in the Proterozoic might have been a bit less strictly microbial than we often say. The Snowball probably created the kind of power vacuum needed to allow previously obscure groups like animals and such to dominate. But just because animals weren't doing much complex stuff before that doesn't mean nothing was.
I wonder if the first undifferentiated multicellular species were capable of switching back and forth between unicellularism and multicellularism as conditions required.
@@mosquitobight Like some slime moulds?
@@petersmythe6462 Yes,something like that, and maybe their descendants lost most of their unicellular phase as they became more complex.
Rhodophyta (red algae) were probably first multicellular organisms. They appeared before 1.0 Ba (billion years ago), it is possible that they might be 1.6 Ba.
Rhodophyta are related to plants.
Awesome. Really well summarized. I have always (well, as long as we have known about it, which isn’t long) been fascinated by the Ediacaran biota.
It seems increasingly that the consensus is that there is less of a connection to the Cambrian, at least than it once was assumed. But then how did the Cambrian life evolve so significantly - it couldn’t have appeared from single celled organisms to trilobites in a million years. So where are their progenitors? Such an interesting puzzle.
Ediacaran is one of my favorite periods (so is Cambrian), thank you for this! There's never enough scientific talk about very early life in my opinion. How much do we know of pre- and eucaryotic things? I only know about the stromatolites and other such microbial mats, is there more?
9:35 - Would it be accurate to say, Rachel, that your favourite arthropods are trilobites?
Insider tip - she was on the UTA geology department soccer team called....THE FIGHTING TRILOBITES!!
Convergent Evolution. Why don't you just say "Yes we know the Annunakii then played a few rounds of Spore"
I don't understand how water itself became more viscous. Do you mean the saline of the unfrozen sea became more viscous due to higher salt content?
Cold water is more viscous than warm water.
Yes, the saline leftover water became more viscous, but due to the cold temperatures not the salt content (because viscosity is temperature dependent: any liquid that gets colder gets more viscous and any liquid that gets hotter gets less viscous). It would've happened with or without the salt. ;)
This may be somewhat superficial reasoning, but I get the impression that the reason the Cambrian is defined as a distinct period from its preceding time is the sudden appearance of a multitude of animal hard parts. It seems unlikely that the first multicellular animals (ignoring those early porifera) to evolve would emerge immediately with such hard parts in place. Therefore they must have evolved from earlier species with mostly or fully soft bodies. This, by definition, would make these predecessors pre-Cambrian, and so Ediacaran. If the Cambrian fauna evolved from Ediacaran biota, and we've found a variety of soft-bodied lifeforms from that time, then what are the odds that the soft-bodied ancestors of the Cambrian fauna would remain undetected, while the known Ediacaran species would only be failed experiments and evolutionary dead ends?
Conclusion: we need to think more imaginatively about how some of the Ediacaran critters gave rise to their Cambrian descendents. While also keeping a lookout for intermediate forms around the E-C boundary. Yes?/No?
Thanks!
Thanks so much! ;D
@@GEOGIRL Great content should be rewarded. Thanks for the good work.
I bet the ediacaran life was colorful.
Rachel ⚡, In your geology 💎 drip you are the bomb 💣!
This is a fantastic video. Connects a lot of dots. One trap people might fall into is thinking there's a discreet end of the Ediacaran and beginning of the Cambrian. Sort of like act one, intermission, and act two. Nothing could be further from the truth. It's a gradual transition. I believe these time periods and epochs are somewhat arbitrary. Therefore, I believe there is a gradual transition or evolution from the Ediacaran to the early Cambrian animals. It's just we can't find them yet.
This is true! And a great point! There is a discrete a transition from the Ediacaran to Cambrian when it comes to periods on the timescale, but biological evolution does not work that way, it was certainly a gradual evolution of new traits that eventually took over in what we arbitrarily deem as the Cambrian period, I think that is so important to note, thank you for saying that! I think people often get the wrong idea from the term 'explosion' ;)
@@GEOGIRL Rachel 🛶!
I think this might be another excellent video. Explaining which fossils disappeared between each period on the timescale; and how many years do the experts allow for transition between periods? Can they narrow it down to one year, one century, one million years? Thanks! Merch!
@@michaeleisenberg7867 There's actually a misconception that the so called "Cambrian explosion" somehow is an evidence against gradualism.
Actually, it looks like that because we have a loss of strata in the geological record, which, in some regions of the world, comprises many millions of years, during the Neoproterozoic Era. This is the reason why it is expected that we don't find the direct ancestors to all Cambrian phyla, even though we have actually found a few in the late Ediacaran, like the ancestors of bivalves and porifera
Periods are often bookended with extinctions, and I think I have seen evidence that there might have been one towards the end of the Ediacaran - something to do with something evolving that destroyed the Ediacaran microbial mats thereby completely upending the ecosystem. Something also seems to have made having "hard parts" particularly important around then that several phyla developed them at once.
But yes, it's pretty much guaranteed that all the Cambrian phyla had some non-mineralised late Ediacaran precursor. The only question is whether we've found those fossils or whether the similarities in appearance are convergent evolution. And on the other side of the equation, it's possible that some of the 'uniquely Ediacaran' biota did survive into the Palaeozoic, but wasn't preserved.
@@Draxynnic Thank you! I quick Google search suggests that burrowing worms ate the mats (whatever made Helminthoidichnites).
never considered low viscosity from snowball waters, i assumed it was due to predation based on a Volvox experiment in the early aughts
I love talks about snowball earth yesss!! Its so otherworldly
Hello mam I am pursuing my msc in geology from India but i had different interest for archaeology. Can you guide me whether these two fields can be combined.
Yes absolutely! You can branch into archaeology pretty seemlessly from geology! And you can absolutely work in archaeology with a geology degree :)
0:00 Ngl, the first thing I notice when I go outside is concrete... 😢😢
Yea that’s the unfortunate truth in so many places now
First thing I notice? The dead hummingbird cats left on my front porch
Geo-Girl, always provocative and interesting. When I was a geology student at MSU, Montana, the Ediacara was as enigmatic like Planet X. Where are the cryptozooic conodonts is this history?
Hmm, interesting, food for thought. The early bit mentioned 'decomposition'; were there bacteria around to utilise or generate the decomposition, in which case, were they part of a symbiotic relationship like mammals and gut-biome? Did they evolve in tandem with the proto life-forms, or were they part of them, like seaweed/algae etc. Just trying to dot the I's, cross the T's and fill the gaps.🤔🙂
I was wondering what Snowball Earth was like. I imagine that over the continents, ice sheets were several kilometers thick, but over the ocean, the ice is much thinner. I was wondering if tides would break up the ice, leaving areas of frazil between ice floes. Which got me thinking, are there significant tides at the poles? Are tidal forces greater at the equator that at he poles? Maybe in conditions of Snowball Earth tidal forces would keep oceanic ice sheets broken up at the equator.
" Are tidal forces greater at the equator that at he poles?"
The FORCES not greatly.
The EFFECTS on the other hand do vary but not pole to equator.
With the current distribution of continents the tidal variation is lower near the poles .
Continental arrangement and varying ocean depths amplify and mutes the range of ocean tidal water sloshing and flows due to lunar influence.
The common bulge illustration is not rubbish exactly but more an idealised smooth surface deep water world without significant disturbance of tidal force influence.
It shows the cyclical nature but not representative of magnitude anywhere.
Some areas of equatorial ocean have very low tidal variation, similar to polar areas, but 1,000 km away there is large variation. Central North Atlantic has low range, European coast has high range.
"Maybe in conditions of Snowball Earth tidal forces would keep oceanic ice sheets broken up at the equator"
Possibly. Depending on continental arrangements and ice sheet thickness, depth of oceans under the sheets and tidal flows under them.
"when you go outside, what do you notice."
Mostly that it's not the middle of Greenland.
One of those species back then was our direct ancestors, tracing back down our lineage.
Trilobites are great, but I'm holding out for quadlobites.
Hey are you great lady . You work hard and made video for us. I love it😍🥰
nice video 😊
Thank you
Cover the Edacrian more, pls
More is coming on this :D
If it's true that Snowball Earth triggered multicellularity then without that event Earth today would be the same as it'd always been: single celled life and that's all.
Geo Girl rocks! ❤🎉😊
The real important question is what color bucket hat should I get?
That's a tough question! haha I have the green one and love it :)
Thank you for your videos
Won't it be great if We could travel back to before the Cambrian period, take DNA samples from the multicellular life forms from back then and then travel to the Cambrian period to take DNA samples from those life forms and then go back to the 21st Century to do a DNA comparison?
You learn so much more when the presenter is cute. After the ice most niches were open and everything was tried.
Wow, look at some of those weird early life forms. I wonder what they could have evolved into if they survived.
hi. How cyanobacteria survived the Earth snowball ?
It's likely since cyanobacteria lived in microbial mats (layers of different microbial communities that provided each other nutrients), they didn't have the same degree of difficulty as other microbial organisms that didn't live in community mats because these mats are essentially multicellular organisms (even though they are made up of single-celled organisms) since their communities of microbes mutually benefit each other by providing each other nutrients :)
Millions of years of soft serve sundaes before Gaea invented cones.
2:01 Doesn't microbial life continue to dominate the earth to this day? Do you mean animals outweigh microbes perhaps?
Did snowball Earth force animal evolution? That's like asking is the Pope catholic, it's a sure bet that that climatic effect had a profound influence on animal evolution.
Kind the biota that would fit europa's moons and ❄ ❄ moons with heating oceans underneath
I’d like to propose the coining of a new term: “discovery bias”. I think (more in the past than now) people have not considered different types of life, or body plans, or well, anything, because we can’t find them with their inability to fossilize.
Probably a subset of survivor bias.
It would be very interesting to trace flora mtDNA vs fawna mtDNA ancestry to see where the closest relationship is. While it's possible that (thinking)fawna mtDNA evolved as parallel evolution in separate instances from flora mtDNA, it seems much more likely that generally fawna's mtDNA followed host eukaryotic DNA conception bottle necks and has a broadly similar family tree to eukaryotic host DNA. If so, it's another strong hint that consciousness of fawna is inextricably entwined with mtDNA. And nothing else is physically closer to our eukaryotic host neural networks. Conveniently in "The whispering mitochondria - youtube", mitochondria have been found to communicate with each other. As with inventions, it takes a certain level of public new knowlege to promote seed ideas to inventors for parallel development of new inventions. With consciousness, we are now familiar with the concepts of fungal maze solving, massivly parallel computing, distributed intelligence, neurons, axons, dendrites, communicating mitochondria, conception, passing of mitochondria through the mother's egg and we have all the hints, mitochondria are a part of consciousness in all of earth's conscious species. Not only that, but they are well placed to pass the data component of instincts through their intact cells across the data bottleneck of conception. Every one of us is a "Noa's ark" of mitochondria carried in a eukaryotic host. The mitochondria have not coevolved through the millenia to be powerless in their host transactions, the co-dependence and synergy is total.
We will get more stranger early finds. I'm convinced we will get some big finds. Life before oxygen proliferation, may have had to do some strange things.
Ediacaran biota looks like animal plants! They look like plants, but they are actually animals!
Aren't stromatolite mats multicellular? And, aren't the Cnidarians and Ediacaran similar to Stromatolite?
Stromatolites are just mats (or stacked layers) of single-celled microbial communities ;) So, they contain multiple cells, but are made up up unicellular organisms. I think you may be thinking of stromatoporoids, which are an ancient reef-building organism that is extinct now; these were potentially more closely related to phyla like porifera (sponges) and cnidaria (corals). :)
@@GEOGIRL well, I'm glad I brought it up!
@@GEOGIRL I'm re-reading Horace Judson's "Eighth Day of Creation" to re-find a quote. I went through a blog of mine to put all the quotes into one ebook, and I've lost track of this one quote. Well, I found this one remark from James Watson(of DNA fame),
He said that one should be at least partially unemployed to do great things. I thought this was interesting in light of a conversation we had about getting a Phd, and doing Phd research. That doing research under Phd, or even being a Phd and being paid for research for a certain amount of time is to restrictive.
Wel, I thought this was interesting as confirming my feelings about it. I could not have made my book on a one or two year paid leave program for being a Phd!
In the book The Sixth Extinction, the author states that conditions on Earth have been beneficial for complex multicellular life for 750 million years, and these conditions will disappear in 750 million years. So, intelligent life emerged exactly in the middle of that period. That leaves us a lot of time to figure out future climate changes, what we can and cannot do to keep life going, and how we can (and should) save our ecosystems and carry them with us if we move away from Earth someday.
You Rock.
Convergent evolution, like steak knives for teeth and powerful crushing jaws... once it grabs you that's it! Like crocs! Rex could probably death roll
Wait, you have trilobites on shirts you do not own?
TRILOBITES….
YES!
Has there ever been evidence of a species diverging and then merging back together?
The 'braided stream' is the current model of evolution and yes this is more common than not.
Humans did this, for instance, as we reabsorbed outlier groups like neanderthal and denisivand.
Love your content. You deserve more subs! Hopefully the Algorithm will pick you up soon 🙏
Thank you so much!
Diversity doesn't happen when things slow down... it's when it speeds up that things take off... leading me back to the sun!
Observing bacterial, fungi colonies is easy to imagine they jumping to this state by having open enviroment insted of petri dish and no predators! I bet the salinity and stable (low entropy) and crystal like (hard shells) jump all bacteria into multi cellular system's
Finally ❤
I really appreciate these sunday morning talks. Today's was no exception. I will say, I don't think of it as our animal origins, I think of it as our DNA origins. Maybe it's just two ways of saying the samething.
Other than that, I was pretty much lost as usual. I think I'll get geology for dumby's and start from there. Lol 😆
Peace and Ahev
❤❤❤
I'm not completely close minded... I'll think long and hard over what you say 😊
💙
"Did Snowball Earth Force Animal Evolution?" No, but it did ERODE evidence of the earliest animal evolution.
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