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Do new traits in evolution happen slowly, or all at once? Two new studies in the journal Science may finally help us solve this mystery.
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I think the important bit a lot of people are overlooking is that if a trait isn't significantly harmful, it's basically got a 50/50 shot of sticking around just by random chance. So there's not always a pressure to keep something, as long as there's no pressure to lose it. And if a combination of neutral traits work together to become a beneficial system, then natural selection will start exerting the pressures to keep all of them together.
i dont think people really think about that stuff at all. 😂
Basically this. It's really quite simple.
@@brulsmurf I mean, it's kind of important; otherwise you spend a lot of time thinking "what caused this to happen?" when sometimes the answer is just "random chance".
@@brulsmurfYou never just, _wonder_ about things, for the sake of wonder?
That sounds like a really boring existence.
@@combogalis that's not how evolution works. The beauty is that no change in the process is really intentional with the benefit of the species in mind. Some just are. And no one is really "selecting" for these traits. These traits just become more common as their benefit makes them better at survival and increases their chances of reproduction.
Isn't an eye is a bad example of this, since you can have a very basic light receptor that is already useful without all the lenses and whistles
It's a terrible example and there is a ton of evidence on how complex eyes like our evolved. Take something as simple as a pin hole camera and you can end up with an extremely detailed picture... Clint's Reptiles recently put out a video about squids or cephalopods... Not sure which, but it was a recent video and explains the evolutionary process of eyes and how they vary in species that evolved them completely differently than we did (the cephalopods are that species). Fascinating video.
Not only is it a terrible example, it sounds like a classic creationist anti-evolution apologetic argument called irreducible complexity. This was an incredibly poorly written video.
like a Tuatara
Wow, your eye can whistle?
@@StretchyDeath Yours can't? Weird.
The eye is a really bad example for this, since we know so much about how it evolved intend incrementally. It is tempting to think that what some biology is selected for now is what it was selected for in the past, but that's not necessarily true.
Agreed. The eye example is bad and worse, misleading.
This is the last drop for me, using the same old debunked example made by creationists frauds...
They constantly have bad takes for even the most simplest things, this is the last one I'll hear from them
And the thing about "what is the purpose of this thing?" regarding evolution is their recurring meme (no pun intended).
I think the fact that we know so much about its incremental evolution makes it a /good/ tool to make the point. Complex systems don't typically spring into being fully-fledged, like Athena bursting from Zeus' brow. You start with something simple, just a few light-sensitive cells, then an eyespot. Then onward.
Knowing what we do allows us to highlight how bizarre it is when a complex system seems to have spontaneously appeared.
Also I'm suspicious that it's a reference to the Wrinkle in Time books. There's a whole thing where the protag meets this race of eyeless humanoids and she finds herself completely unable to explain sightedness as a sensory experience even though it's fundamental to how she interacts with the world.
Maybe also light pushback on creationists who still try to claim eyes are too complicated to be the work of anything but an omnipotent deity (yes, they do still exist).
@@ajchapeliere Darwin himself gave an explanation for incremental evolution he eye, while they say "it has to have a lot of things evolving together to make sense" just like every creationist fraud.
We have lots of different eyes, vertebrates, invertebrates, insects, and more... it has evolved multiple times in completely different ways, even among mammals we have differences.
It's a mix of both. Most of the time it is gradual, but sometimes when the circumstances are right it is relatively fast.
Yup! If some mutation ends up absurdly useful relative to lacking it, it’s going to spread rapidly.
@@darkstarr984more often it seems it's some new environmental pressures spur rapid evolution like the great oxidation event or a new predator being introduced that exert a lot more influence on the native prey species
Yep.
Traits get selected for all kinds of reasons in the good times.
Eg, with people, perhaps it became fashionable to have ultra skinny legs for long enough that it made a modest portion of the population.
That's the good times.
But then the environment changes. That's the test.
Do those traits survive the change?
If the skinny leg people survive in greater numbers, then it is likely to define the direction of evolution.
Exactly. On an evolutionary scale fast doesn't mean all at once.
@@12jswilsonOr through a culling event, like the chornobyl nuclear power plant disaster culling frogs with less melanin
Ever since I've heard of the bombardier beetle and how it has 2 separate storages for 2 separate chemicals, that are then combined at its rear end and turn into an explosive gas, I've been questioning how the heck did that thing evolve to have that.
Its Wikipedia page even has a section all about the evolution of this mechanism.
Like the two-headed dragon in How To Train Your Dragon?
@@DonnaBarrHerself Kinda but in that case was one head spraying flammable gas meanwhile the other just ignited it. Bombardier beetle in the other hand mix both substances at the instant it releases them, because they will react immediately. Having both already mixed as storage will be just lethal.
Things can get doubled sometimes.
So there may have been just one storage compartment, and one chemical. Then a mutation doubled the chambers, with both Chambers having the same chemical,, and over time it evolved a different chemical mix.
@@Robert-do3cd From personal experience I'd say mutation is attributing changes always to external factor. As if we never have control over it. Yet introspection has made me question that being the case. Not that we can will thing to happen but intent over time should be able to steer us in X direction. Probably why we keep on developing our brains - we have continuous intent in many individuals for it to happen. We could level it as "mutation" and call it that but I think it's about intent that supports mutation to be on average favorable in this direction. That's just my few thoughts on personal experience. And since these beetles are also living organism with intent I'd say I can't call your logic wrong. Seems plausible. Likely in scarce situations the beetles had to test out new chemicals in there because they lacked enough for the original? I don't know. Interesting to think about.
@@HHalcyon there's no intent, no conscious anything, in evolution by natural selection. please learn about it and about genetics.
Oh, yeah, the eye is a really bad example. Not only have eyes evolved independently multiple times, and also the same kind of eye (octopuses and mammals have the same kind of eyes, but the former avoided having a blind spot), but every tiny increment along the way is beneficial and explainable. The only kind of vaguely puzzling thing about our eyes is the development of bands of muscle for focusing the lens, and even that's well understood!
The Phineas and Ferb reference at 5 minutes is hilarious. @Dantible
It's a massive mutation of the original phrase but it works better and therefore has prospered. so it fits
OMG I had no idea that was a Phineas and Ferb reference! 😂 Thank you for this information! (I've now looked up and seen the meme.) I took it seriously and criticized him in my comment, for the very misleading statement since, scientifically speaking, it's not weird at all. Gotta be careful with those memes because if somebody doesn't know the reference, you'll go right over their head! I love P&F though.
@@sharonminsuk it's always fun to learn something new!
I immediately looked for this comment after getting to that part of the video.
Doofenschmirtz is the best TV dad
The pitcher plant example has some flaws. It seems that the main function of the lid in most species is to keep rainwater from flooding the contents of the pitcher. That in itself is a valuable function. There are close to 180 species of Nepenthes, and though there are a few exceptions, most of them have lids that cover the mouth. (In a few species the lid serves other purposes, or almost no purpose at all.)
It also often serves as a “landing pad“ and, like most of the pitcher surface, also has nectar glands on it. it stands to reason that nectar glands on the underside of the lid are more useful toward luring the prey to the mouth of the pitcher. the “catapult” function seems to be sort of an extra added bonus, since it only functions when it’s raining. But if you already have a lid where insects would congregate and feed above the mouth of the pitcher, plants that caught more insects because of catapulting could end up producing more seed.
So there is really little likelihood of the lid “suddenly evolving toward a catapult;” instead, it seems perfectly logical but it would be a “fine-tuning” of lids that serve at least two functions.
The lid of the pitcher is to keep rainwater out and filling the pitcher, making the pitcher too heavy to be supported, and it would dilute the digestive enzymes rendering them inert and unable to breakdown insects into a usable form.
The springboard is just a happy accident, insects take shelter from the rain on the underside of the leaf and getting knocked into the pitcher is a coincidence.
my guess of Evo sequence would be Slippery leave> Pitcher shape > Enzymes> Top Leaf> Modern Various forms
@@ryanfitzalan8634 Wouldn't it make more sense for the pitcher and top leaf to evolve together.
i love the happy accidents in nature. I've noticed however, that human perception gets in the way at the same time it admires. You know?
@@user-vr2qp2hi8z Yes, and the springboard theory is a good example.
Insects take shelter on the underside of leaves when it rains. The lid of the pitcher plant must be stiff enough not to collapse under the additional strain. It is not an evolutionary adaptation by the plant to catch insects, it is merely a co-insidance, a convergence of two facts that benefits the plant. But people seem unable to leave it at that and feel a need to over think it.
@@chrisjohnson2460 its not implausible, but my thought is always that evolution follows the path of least resistance, and thus tends to be conservative in design, so the least number of physical changes and the least number of genetic changes tends to be simpler and more probable to occur and achieve success. a slippery leaf is valuable to keep pests off, pitcher shapes have various uses but are more complex a trait, enzymes are likely a complex trait and require a pitcher first for them to be useful, the top leaf is simple and possibly unnecessary at times since it has the most variety in form and use across the various species and thus is the most recently adapted trait
Evolutionary pressure is a scale related to how beneficial a trait is, on a range of scales directly or indirectly, for furthering those genes overall.
This means that even slightly disadvantagious traits can be passed on for a while in a population.
This negative trait can then be modified by further mutation and become beneficial in the end.
Neutral traits can spread unhindered in a population.
Everyone of my ancestors fathers didn't look noticeably different from their sons, traced back from being human to an amoeba 4 billion years ago.
3 billion i think. The first Billion the earth was cooling i think
There are Zircons from Western Australia that have radiocarbon decay associated strongly with life that are 4 billion years old, so its possible that bacterial life was starting 4 million years ago @Wilsoul
You got me on that ending.
I like to imagine our earliest common anscestors that were distinctly not human, like single-celled organisms, and getting to "meet" them with a time machine.
"Hello, great x10^100 grand papi!"
@@LeoDVfan When you didn't read the information manual that came with the time machine.
I would assume that eyes started as, like, some light sensing cells under the surface of the skin, and those just became more and more refined and specific because it turns out light's super useful
This is in fact what we know happened and using the eye as an example for this problem is a bad example
@@bengoodwin2141 Exactly. As a matter of fact, this very flawed example is a favorite of creationists and “intelligent design” proponents who don’t understand how evolution works, and don’t want to.
@@sazji I know. There was a point in time when it wasn't understood because it is quite complex, and a lot of the explanations that use this example come from those times, but that hasn't been the case for a while. All things considered I don't think it's always used as an example in bad faith, just out of ignorance sometimes
In the late 1970s, there was a group of paleontologists who proposed the hypothesis of punctuated equilibrium (punc ec for short), in that evolution could happen in sudden rather than gradual changes.
Stephen Jay Gould!
... making me wonder why Gould et al wouldn't have considered this and rebutted this decades ago.
Also: If I had a nickel for every contrived Phineas and Ferb joke, I'd have enough money to TAKE OVER THE TRI-STATE AREA!!!
This episode wasn't as eye-opening as I hoped.
Divergent Evolution could be a possible answer. Imagine if a population of pitcher plants was somehow separated from each other for a significant period of time and started evolving in two different directions. Then once they started developing their own unique mutations the two groups got reintroduced before they became completely separate species and by pure luck their traits were synergistic
Agreed, but physical separation and reintroduction is not even necessary.
If two somewhat genetically compatible species or subspecies fell into different niches i.e. specialized in capturing different insects - their cross-species offsprings could have occurred regularly - but never had a combination of genes to outcompete either of their parents. Then randomly a combination occurs that happens to combine to do something "new" - well enough to not be entirely outcompeted. Then it starts evolving into perfecting this new thing. Then it might do it so well that is outcompetes one or both of the "parent" species. This is basically how evolution works and this is precisely why we have this whole meiosis (and genders) thing as well as genetical diversity - it allows for such experiments to occur not just through random mutations but through mixing and matching already present features which is much more efficient.
That is literally the example in the video.
Wait, we only just have a study on this? I remember discussing this in classes 20 years ago.
Eyes: start with being able to detect photos on tissue, select for better ability to perceive photons, select for a membrane to cover the area, select for ability to distinguish wavelengths of color, select for... you get the point.
Evolution is a slow process usually involving one change at a time, although much more rapid than we used to think with the validation of Lamarckism with DNA methylation. Natural selection would certainly benefit from synergy between separately evolved traits, but that's not a reason to suggest that any of it happened all at once.
There are examples of all of the stages present in different animals today.
Lamarckism - isn't that a theory that was discredited long ago?
@@view1st I think it got discredited (in favor of the natural selection theory of evolution), but then we found out that while mutation + natural selection is the main process behind evolution, and that it doesn't quite work how Lamarck thought it did, there are some processes (DNA methylation) that mimic Lamarckism. My understanding of Lamarck's theory is that he thought creatures evolved during their lifetime in response to environmental conditions and passed on their changes to their offspring - this isn't how most Evolution happens, but DNA methylation (which doesn't affect the genome itself but controls which genes are expressed) can change in response to environmental factors and be passed down to your offspring. This is responsible for both a lot of our individual variation, and also some of the rapid adaptation that takes place in response to an environmental change - akin to Lamarck's theory of evolution.
5:00 you know it gets real when the science channel quotes Dr. Heinz Doofenshmirtz.
they reference internet memes in most episodes
Ahh, A Phineas and Ferb reference, what an unexpected surprise. And by "unexpected", I mean...
COMPLETELY EXPECTED!!!
I had heard that punctuated equilibrium was one of the solid explanations for gradual and fast evolution. Gradual changes that broaden the gene pool conferring neutral traits that confer no advantage nor disadvantage. Then, a change in environment occurs, usually over a short period of time and some of these formerly neutral traits are significantly beneficial for reproduction compared to others. The other traits may survive in an area where the environment didn't change much, but for species in the changed area only the formerly neutral traits survive. Eventually, they become unable to interbreed due to gradual and punctuated changes.
I quite like this explanation tbh, because it really demonstrates how evolution and natural selection can be a bit loosey-goosey sometimes, evolution is quite slow when there are few selective pressures and most organisms are already fairly entrenched in their environment. New improvements are quite rare, since things reach an equilibrium point (or some sort of steady cycle) eventually. A predator can't just evolve to be faster, and faster, and faster, or bigger, and bigger, because there comes a point where the costs outweigh the benefits. But evolution doesn't stop just because creatures are already well adapted, there are always some mutations that are just... there. Maybe they are mildly useful/harmful but just don't make a big enough difference to be selected for/against, maybe they're tag-alongs to actually useful traits, maybe they don't even get expressed, but regardless, traits like this build up over time.
And it's also why a lot of special adaptations seem so 'creative' and efficient, so many things on organisms have a ton of different uses, because it's easier for evolution to coopt an existing system than to create entirely new ones. E.g. butterflies have tiny scales on their wings that reflect light in specific ways (structural color), but those scales didn't evolve just for color, they were already being used for flying, heat absorption, water-proofing, etc. Whereas us mammals don't really have a good way to evolve structural color, so we're a lot more dull and adapt in different ways.
Loved that Phineas and Ferb reference ❤
That was a bad example. Eyes evolved in previous, more simple organisms long before humans. The eye evolution "problem" has already been explained. As Richard Dawkins said to some creationists when they tried to challenge him with this, he pointed out that a single light sensitive cell on the surface of an organism is more useful than no light sensitivity at all. Later, a protective but transparent membrane might evolve to protect it or muscle cells somewhere in the vicinity could allow the organism to point the light sensitive cell or area in different directions, allowing it to tell that there is light that way but not over there, which could help with finding food, finding warmer or colder areas, avoiding potential predators, etc. Then, another mutation could lead to the formation of a vacuole around the light sensitive spot/area, which might get filled with interstitial fluid from the body, and this would add some focusing abilities, with the aforementioned muscles that move the proto-eye around could be used to squish or stretch the vacuole or allow it to focus on objects at varying distances. Later mutations could refine this into a more effective tool, such as by duplicating the protective membrane and then another mutation thinking the inner membrane, making a lens. Another mutation increases the number of light sensitive cells and other mutations lead to other beneficial traits. you seem to be thinking of organisms like mechanical machines, with static parts that don't do anything on their own. Organisms as we know them, however, are made of chains of chemicals that interact with each other in different ways, so any individual mutation will do something and the rest of the organism will adapt to this new trait. So, no, you do not need a whole eye for it to be useful.
There is no such thing as irreducible complexity. The real evolution of eyes was very gradual, as we can observe many intermediates today. It isn't at all mysterious.
Exactly. All of recorded human history is about 5,000 years. That is a BLIP in the history of Earth, which involves half or more of species getting wiped out several times because none of their members could survive new conditions. I’ve often said that if HIV had spread the way the flu does, the human species would have been hard-pressed to still exist today. Very few of us had the mutations for natural immunity. 😬
Intelligent design is just a lame attempt by Christians to make Christianity scientific, like keep dreaming guys, we can all tell it's just two dudes in a horse costume
It's why the eye example was bad, as other commenters have already said.
@@AngryKittens yeah, but... I don't think that was the point or a claim within the vid. In fact, my read of it was the opposite, and the eye example was more about the discourse around the complexity of eyes, rather than any sort of affirmation of, or agreement with, irreducible complexity. Did we watch a different vid, or... ?
@@caydennormanton9682 Of course it isn't. That's why it was a bad example in a video specifically about evolution.
They picked a random body part, and ended up with one commonly claimed as being evidence of "intelligent design", despite the fact that it's no such thing and its evolution is pretty well-attested.
They inadvertently made it seem like they're talking about something related to ID, when they're not.
From single cells that could detect light such as plants with phototropism it is not hard to envisage groups of these to be more beneficial and finally cells to help the light focus. This vid does not mention this evolution has a lot of dead ends and only some of them become useful The fact that sight of some form is ubiquitous in most land species means it is useful and therefore will eventually evove. It does not need a sudden leap.
A mutation does not need to be beneficial to be passed on, it just needs to not be detrimental to the survival or mate selection process. A peacocks tail is not great for the bird from a survival angle but is important from a mate selection angle. If the peacock had a mutation that caused all the color to fade from it's plumage it would not get mate selected but if that same mutation expressed later in life it could still be passed on and mutate further.
Since the vast majority of past life on earth died without leaving any fossils or genetic information for us to find, it's amazing to me how much researchers are able ascertain about the (often ancient) evolutionary history of specific traits like these.
So many genes are involved in vision that it could not have happened in a single massive mutation. Vision-related genes include... components of the photoreceptor signal transduction cascade (GUCA1B, ARR3), a factor required for retinal organization (CRB1), lens crystallins (CRYBA1, CRYBB3, CRYGS) and the cornea specific keratin 12 (KRT12), and probably a whole load more.
Don't forget the nerve that transmits data and part of the brain that interprets it.
Of course: it happened in a gradual way.
It's a remarkable case, showing how complexity arises from small changes.
It tends to happen in several stages, one mutation at a time, often with a long time interval in between.
The editing in this video is on point - keeps me engaged the whole time
My guess would be that there are four things at work, not just two. Slow, gradual change, as most of the evidence indicates, with the occasional grand mutation that just happens to provide some benefit either immediately or doesn't create such a problem that it is actively detrimental (which eventually becomes beneficial), and reactivation of dormant genes that were acquired through either mechanism, and just so happen to remain activated when passed on, that confer some benefit that had lost its significance due to changing factors. Finally, as in the example with the pitcher plants, crossbreeding; a mutation, either the slow or rapid kind, gets bred into a population from a closely related species in which it had already become a dominant trait.
I'm assuming its both gradual and big leaps. Because eyes for example as far as I know started as just some light sensitive cells like the third eye lizards have, they probably got more and more refined over the generations, but turning into a ball that can rotate might have been a way bigger leap.
Both. It’s generally a slow burn, but with rapid spurts interspersed. One should remember though, “What is time?” Millions of years are but a blink of the eye the further you go out.
Im not sure I understood correctly so let me know if I’ve got it wrong - changes like these don’t happen all at once, but rather have a “hidden” foundation built up for them gradually, and then a single small change suddenly “activates” the trait?
i find it varies, in some cases it could be a specific trade sequence, or if there are a certain amount of xp, or it could be artificial, like if you have a thunder stone for example
Enjoyed the call-out to Dr. Doofenschmirtz ...
sudden Doofenshmirtz reference caught me off guard. 😂😂
Your reference got that jingle in my head
_Doofenshmirtz Evil Incorporated!_
Wait what jingle? 0.0
Interesting stuff. But how does this episode not mention Richard Dawkins and his debunking of the "blind watchmaker dilemma"? Showing that each incremental stadium of a "partial" eye wouldn't only function but also it still actually exists in nature somewhere. And not only was it not mentioned, but the eye is even presented here, in a somewhat misleading fashion, as some kind of mystery of evolution even though that mystery was already solved long ago.
answer: YES!
Gotta love "or" questions.
Yes From a certain point of view
@@084ironman And he was a very good friend....
Punctuated equilibrium!
Sapolsky??
There is something weird with this video, why chose the eye as an example when we know how it evolved pretty damn well! Also these traits don't seem all that complex, the snail one maybe i guess though to me live birth in formally oviparous animals seems simply like waiting too long to lay the eggs and when you do they come out already hatched.
But the pitcher one seems more like a happy accident, they need a lid to prevent rainwater from overflowing and/or diluting the juice and it happens to knock insects in when hit by a drop of water, like any type of semi flimsy leaf would also do, hell it would be more impressive if they somehow evolved a lid that didn't shake so much when hit.
To play devil's advocate i guess having a leaf protrusion to prevent rain water from entering is not the best way for only that specific purpose, like why not just have a "U" shape, and we see this in the pitcher plant the Cobra Lily so maybe the lid does have more to do with catapulting bugs in than as an umbrella, though it's kinda weird as this would only work when it rains.
I mean, in those areas, is it that it rains more than it doesn't rain? And isn't the humidity especially high, whether it's raining or not?
Just curious, as that would make those conditions rather baseline/expected, as far as environmental factors are concerned.
@@radikaldesignz I don't it's raining more than it's not raining, also you would think bugs try to seek shelter when it rains and not go drink nectar
I have wondered about this so much!! Finally, an almost-answer.
I've always thought it was understood random mutations lead to incredible outcomes. In a complex world, anything is possible (as long as it obeys the laws of physics).
It's pretty clear what happened, actually. 3 favorable traits that suddenly appear and work together for a favorable result, and not just once. The devs added them in an update.
Someone's been watching too much TierZoo
I think an eye is a pretty bad example of something that must be sudden, or something that would need multiple convergent mutations. If you're a cambrian slug and develop a rash that's sensitive to light, you get minor sensory awareness when there's a huge predator between you and the sun, that's a potentially minor change with a huge upside. You'll be favored and your kids could inherit it. hey, if your kid mutates a slightly BETTER version of that new light-sensory organ, they'll be even more favored. and so on. thousands of generations later and its ability to sense light gets more advanced, turning from a binary sense into a rash that can pull in multiple pieces of information at once, with a small muscle to swivel it to collect even more. i really don't buy that eyes are an all-or-nothing mutation, even the most simple possible version of it is really helpful.
Idk why I even bothered watching the video. I should’ve just asked you. You’re smart af!!
IKR, this video feels like a first draft.
Just because we don't know what the benefit was, doesnt mean it had none.
We might simply not understand what these plants did back then and how their pray worked.
Also as mentioned a non.harmful trait might simply stick around... and then another... and suddenly you have a psringboardtrap that works and eradicates the rest of the competition.
It's so crazy to me that the "two nickels" meme from Phineas and Ferb has become so popular on the internet recently. But I'm loving it, it's my favorite episode of the show.
0:41 Actually, that show has already been made. It's called "See". It's on Apple TV, has Jason Momoa, and is awesome.
All together he'll have 30 cents which is a little bit over a quarter😂
35 cents
@@BenjaminBrienen wait ! Really? damn it I was off by 5 cents?😂
The study completely side steps the more interesting question of what drove the pitcher plants to evolve the means to lure, trap and digest insects for nitrogen and phosphorus if they have no way of knowing insects contain those minerals in the first place. Don't get me wrong, the spring boards are cool but they are a very tiny piece of this puzzle.
Pretty sure nothing "knows" it'll get nitrogen and phosphorus.
An interesting part of mutations is:
1. Small genetic changes can sometimes have massive effects. Things like the size of a species can change dramatically in a short time without requiring many genetic changes at all.
2. Genomes often contain big supressed sections from ancestors from millions of years ago. This can cause entire complex traits which once required a lengthy evolutionary process to come up, to re-emerge in an entirely new context.
1:05
Stefan: So a fin becomes a leg and later...
Cetaceans: A fin!
Stefan: ...a wing.
Cetaceans: Oh.
Okay but eyes did develop slowly. From basic light sensing cells. Something plants can do. Anything that is able to respond to light has the potential to evolve into an eye. It just becomes a little more concave, a little more sensitive, a little more focused. Develop a membrane or two. The brain in most animals with a brain only began to evolve as an overgrown optic nerve which needed more and more resources to process what it was seeing. Eyes are so easy to evolve that not only have they evolved independently multiple times throughout Earth's history, there's a pretty good chance alien complex life would develop them too if there is any light in their environments to see with.
I also don't know how to feel about this video as it might end up appealing to the wrong crowd of conspiracy anti-science nuts. Personally I dislike the argument that "eyes couldn't have possibly evolved!!! If you remove any part from a fully functional eye then it stops functioning, therefore-!" Yeah and if you take a hacksaw to a fully formed brain, it stops functioning too. It did evolve up incrementally. Dismantling it isn't the same.
I'm not surprised, the E. coli Long-term Evolution Experiment already showed something similar. One of the populations of E. coli in that experiment spontaneously evolved to eat citrate, but that new trait required multiple neutral mutations to build up in the E. coli before any selective pressure could occur.
That's essentially a kind of punctuated equilibrium evolution, where neutral mutations cause slow genetic drift with occasional mutations that synergize with previous mutations to make new traits that can be acted on by selective pressures.
Eyes have a long and slow evolution. We have plenty of step, by step living examples.
Read the novel "Darwin's Radio." It proposes evolution by "saltations" or "jumps."
I would argue that for eyes, they may have started when an organism, through mutation, developed something that enabled it to differentiate between light and dark. It may have enabled the organism to either evade being eaten or to better find food.
Eventually, there is another mutation in the ones that have the sensing organ to vaguely identify shapes.
Eventually, with enough mutations of "this helps, that doesn't", you keep edging closer and closer to what we have today.
i agree, gradual improvement, then occasionally the big leap forward. eyes help a lot in survival of organisms so any improvement is selected strongly for by natural selection
I would suggest that rather than being selected for, it was a case that those traits were not selected against long enough for them to produce something beneficial and then the traits were selected for.
Clint's Reptiles recently made a great video on similar topic. It was supposed to be about squids but he ends up describing how eyes of squids work and evolved.
Thanks for reporting on a new paper (2024!), I love hearing about the new studies!
And this is all without even counting other coincidences like a retrovirus directly messing with an organisms' reproduction, at just the right timing when other innovations came together too. (I'm thinking of the evolution of the Placenta in placental mammals)
That would be fascinating to see how things could've been so different
There's a general miscoception about evolution: it doesn't promote "better" traits, but instead it do not allow the organisms that not suite a certain environement to grow and reproduce. Thus it can be both gradual or sudden depending on the gradual or sudden changes of the environement.
I love this : ) Maybe the discrepancies are happening because of biased preconceptions concerning what is expected to happen. In other words, there are factors of which we are not yet aware of that also can effect the outcome.
I enjoyed reading Stephen Jay Gould's books and he had a theory he called "punctuated equilibrium" to account for the seeming non-linearity of evolution. Wonder how that's viewed by current scientists. Interestingly, his major studies were done on mollusks. Thanks for your channel. I've watched many of them. Be Cool.
I feel like the fish or micro organisms we evolved from eventually evolved light detecting groups of cells that helped it know if it was near sunlight and this was the starting point for different eye types
We needed stefan to do a duffinschmirtz voice
This is honestly hilarious. More like this one!
I think part of the difficulty is that we’re looking backwards from the pitcher plant as the somehow inevitable result and wondering how it could happen. But if the pieces had come together is a different way, we’d be wondering how *that* could have happened.
I love the Dr. Doofenschmirtz reference!
Get this man some nickels!
I read this in Doofenshmirtz’s voice for some reason
Eye is a weird choice as an example considering it's one of the Creationist camp's favorite 'It couldn't just happen' arguments. When we DO know a lot about the evolution of the eye from light sensitive cells, to clusters of cells, to a cup shape, etc, etc etc. And we have tons of different eyes throughout the animal kingdom at different stages of evolution as examples.
The rest of the video is great, but the eye example is a miss. Sorry guys, this is a rare fail for you.
Both, there's the example of that hurricane on an island that left only the lizards with larger finger pads or that species of flower that the entirety of the species grew to be camouflaged because humans were harvesting it to extinction & things like environmental changes that select out for different desirable traits, like if an animals environment slowly changes to desert their short claws and longer fur may switch to longer burrowing claws, but that's just my opinion.
It seems like this video should have hit this topic a little harder and gone a little deeper, especially with regard to the human eye. The evolution of the eye is one of the principal arguments used by creationists to debunk natural selection, and the cartoon picture of a cave woman with no eyes, holding a baby with big eyes, although funny, it does nothing to dissuade those who decry evolution in favor of creationism. Obviously there were never any early humans that had no eyes, and this really should have been made more clear. I know this may seen ridiculous to the average SciShow viewer, but creationism is a real problem in this country, and in my opinion it needs to be hit hard with the facts and information we currently have at hand. Perhaps the focus could have remained on eyes, demonstrating how light sensitive cells in early animals eventually evolved into fully functioning eyes, each subsequent development being advantageous to the organism. I’m fairly sure that no serious scientist today believes that god simply waved his hand and gave humans sight. There was never a point at which eyes simply popped into being from one generation to the next. In fact, we now understand that eyes developed at least twice in the animal kingdom, both times in a similar fashion. Perhaps a subsequent video on just eyes would be helpful. Thanks
@SuperManning11 You should watch the video of Richard Dawkins debating with a creationist which I referenced in my other post. Dawkins explains pretty much everything, as you noted, and then the preacher asks him the original question again. The look on Dawkins's face is a real laugh out loud moment. He asks in shock, "Haven't you been listening to anything I just said for the past ten minutes?" or words to that effect. Comic gold.
Agreed and downvoted the video because of this.
@@chrisd7733I’d love to see that! I scanned through the comments and didn’t see your post with the link. If you could post it again here that would be great. Thanks!
@@chrisd7733 found it! Thanks!
Step by step eye evolution over time is entirely workable. As you evolve a better protective layer that is more transparent and protective to the cells that detect light, you get a nice collection of dense cells behind a lens. Then as this lens becomes valuable you might get an eyelid. But as this lens evolves and the bundle of nerves that deliver signals from the bundle of light sensors to the lump of brain that is evolving to make the best use of the signals from the evolving light sensors, you get a mutation or two and the survivor has colors. At some point, as the lens is delivering data, muscles that can alter the angle of the lens evolve allowing less movement required to get data and that improves stealth. This allows the evolution of eye sockets and then a mutation that alters the shape of the lens suddenly gives you more data. This allows the evolution of focus. Each step gives an advantage. The entire process takes a whole lot of generations, but advantages can be seen for every single step on the way.
Very well described! This is what the video should have focused on. Thanks for filling in the needed info
Micro evolution:
From the goo to you via the zoo.
From the infantile to the reptile to the crocodile to the gentile.
"Micro" and "macro" evolution are terms made up by anti-intellectual anti-evidence creationists
The way eyes were presented as an example was really poorly laid out. We know exactly how eyes evolved over time, from rudimentary light sensing cells that just react to the presence of any light, to more complex clusters of light sensing cells that can allow the brain to generate rudimentary images of shadows, to more complex eye structures that allow the brain to tell the difference between different shapes and colors. Of course theres more to it than that, but i just feel this video wasnt that well thought out.
The writing in this one was hilarious lol
This video seems overlysimplistic and yet confusing at the same time
Eyes seems like a bad example because we already know it couldn’t happen as a complete trait and we already know how it happened in different ways in animals that evolved eyes in completely different ways, so we have more than one example.
Some traits could be: sensing in other dimensions; remembering future events; increasing survival against catastrophic cosmic events or super volcanos. Some of which may be linked with things we consider genetic disorders. So will soon be 'cured'.
This honestly feels like the only bad episode of SciShow I have watched, convergent evolution happens all the time and pitcher plants are no exception. Two we have a fairly good idea of how the eye evolved, starting as a light sensitive cell, that bunched up, got more accurate and migrated in some way to focus the input. Thats why there are so many convergent evolutions of the eye. It didn't happen all at once it happened everywhere and has been since there was animals to see light.
All it really said was evolution is nearly random and we don't understand it fully.... well duh.
The doctor doofensmirtz quote is crazy lol
eyes is not a good example for this question because it's been already perfectly explained when each part of an eye is beneficial to an organism comparing to when they don't have it. Forexample, the simplest eye would have been naked retina, which many simple animals have to detect light and dark, and then the naked retina sink into the skin forming a cup shape, now they can detect the DIRECTION of the light , and so on.
-Hey pal, I think you can add eyes to those stock illustrations.
-Nah fam. Minimalism is more attractive.
-Guess that's how art evolves.
-How ironic. I'm convinced this new models will be used in a future video about evolution or something like that.
-Maybe, but also maybe not soon; there is still nothing of that topic in the board of ideas.
-Yeah...
Hypothesis, test, observation.... that is science. The number of times may have was used in this article is ... well I didn't count. But science would be me making a guess, then Counting. Not saying hmmm, he may have said "may have" 20 times and just leave it at that.
This basic premise *is* an AppleTV show called "See", staring Jason Mamoa. The first season is excellent, the rest of the show is fine.
I think the initial analogy is pretty misleading.
i never understand why many shows/channels show so much of the "producer" talking on screen, when this time could be filled with visuals to improve understanding/give more info. i dont see any sense other than increasing the bondage of the viewer and the producer. maybe thats my minor autism speaking, but i see the first point much more important than the second, at least from viewer's perspective. not so bad show generally, tho
New traits? - The ability to type with our thumbs. (Pssst.) Oh! My God!
I thought that eyesight was a gradual evolution, that some cells started focusing on being receptive to light over time, and just became more and more specialized in that regard. But maybe eyesight is a combination of gradual and sudden changes. So that gradually, those light-sensitive cells became more specialized, and since there were already light-sensitive cells to work on, a sudden mutation gave them the ability to perceive color and depth, and not just light.
The most primitive eyes were just (light) Buds of Photo-receptor Group of Cells..
When nerve ganglion collected together, forming Proto-Brain (eg Platyhelminthes).
Bud of Cells --> Photo-Pad--> Photo-Cup--> Jelly Lens covered on Cup--> Jelly Lens got Tendon Ring--> the whole Cup rotable --> Jelly lens get smaller but controllable (focus) --> tissue covered on lens--> got layer behind lens -->got more layers before lens that can blink.--> rod/cone cells, can see colors ; all these steps are intelligent design on purpose of whom above.?
All the creationists getting moist when he starts talking about an eye
It seems the answer is a combination of both. Gradual mutations happen, but they don't necessarily lead to any noticeable change, until in one or two species, these changes would come together and lead to a sudden very noticeable change. It's loosely analogous to boiling or freezing liquid water. As the temperature gradually goes up or down, there is no visible change. But when it reaches the boiling point or freezing point, there is a sudden phase change.
Wel, if the "sudden explosion" is a valid one, it needs to explain how the rtandom gene combination resulting in eyes happened several independant times over our planet's history.
The eye example isn't a good one, since a suddenly appearing eye wouldn't give ANY advantage, as it also depends on a brain to process the information it gathers. It must hence have coevolved with the brain.
Sometimes, things evolve for unrelated reasons. The appendix is now known to be a reservoir for healthy probiotic bacteria, but it is a vestigial organ that used to digest cellulose. With the pitcher plant? Perhaps the lid evolved for a different reason we do not see, but when combined with the right friction and rain, was then repurposed as part of a trap. That explains independent pieces evolving to do tasks that seem non evolvable; they just evolved for a hidden reason.
Exactly, things evolve for one reason but then get repurposed later when that reason isn't important anymore.
@@ooooneeee oh thank for your response! It’s not just me. 😁🙏🏻
That’s a great question
The current function of a trait may not be the original function it had. Traits evolve to fill other uses sometimes. Sometimes new functions arise as emergent properties in a complex system, and those emergent functions can overtake older functions. Evolution is one area where the essential reductionist process of science struggles to grapple with the complexity of what we’re studying. Life is a synergistic system and often the combination of multiple factors determines how things work. In our study of evolution, the scientific drive to isolate variables can sometimes fail to understand the true nature of the process.
Quite curious that same traits develop ~synchronous on different locations on Earth. There is more than meets the physical eye.
I'm really disappointed in you scishow. This is very low effort, badly explained evolutionary theory and an example like eyes is a very bad example.
There is a lot of evidence on how eyes evolved, and we can even reproduce basic traits with low tech materials. Take, for example, the pin hole camera, which is basically just a box with a very small hole in it.
You didn't even mention basic things like convergent evolution, how repurposing of traits can happen, how non harmful mutations and traits are not automatically weeded out. You also didn't even mention extinction events and how those events can create environments for "rapid evolution" since organisms are a) forced to adapt or die and b) creates openings for niches to be filled.
Seriously, slow progression and rapid change are well established theories in evolutionary biology. What are you guys doing? You wasted more time on your "if I had a nickle jokes" instead of actually explaining anything scientific.
This episode was unusually bad, almost felt like it was written by AI. What were they thinking using the eye as an example for an 8 minute long episode on evolution?
What I want to know is how do some animals evolve to have scary pictures of other animals or traits to ward of predation. Skulls, decomposing body of some other animal. How does it know what that looks like to selectively add it to the colour scheme?