An elegantly intuitive view of evolution

many animals share the same sequence of DNA that controls whether limbs grow or not so if you use crisper to replace this DNA of mice with have a fish a lizard or even a humans the legs will grow back just fine as if nothing happened unless it is from a snake so what's the difference well all snakes are missing 17 letters of DNA within this region amazingly if you insert these 17 missing es back into a python control box and then put that into a mouse as before the mouse will grow legs as if nothing happened but why do all of these vastly different organisms share the same control structure for limbs did they talk to each other before evolving separate ways what's so special about these 17 letters of DNA more importantly how does one randomly lose bits and pieces of DNA and in this video we'll soon find out that the last question is the Ultimate key to answering all of the other ones you probably heard of the age-old tale of evolution being caused by mutations however that is such a vast oversimplification if that were true we'd still be stuck as little Teensy bacteria floating around in some water what I'm going to show you today is a deep dive into the Machinery behind the hand wavy terms like mutation duplication or deletion I'll show you why life is so diverse we'll get to see all of those cogs and gears that make Evolution turn let's start from the beginning just a mere Act of copying DNA to generate more cells can come with errors a DNA copier makes one mistake every 10,000 letters when DNA is copied sometimes the wrong base can enter or sometimes the base can just convert into their alternate form which makes G look like a and C look like T this can can be dealt with in two ways The copier itself can pause and Cheo back this mistake that brings the error down to at most one in 100 million if that fails another mechanism can detect that mismatch and mow off that entire chunk of DNA and copy it again bringing our total error down to at most 100 times to around one in 10 billion as you can see these two fail safe mechanisms are not perfect this can happen because the chew back mechanism can miss the mismatch because the base did not decide to convert back to normal wait but isn't one in 10 billion such a small number it can just be rounded off to zero well no let's look at something as simple as eoli its genome is around 4.5 million letters long and that means in one cell division it makes 4.5 million in 10 billion mistakes that's still small but consider this that's only one cell division and each generation the number of cell division events increases twofold so after say 21 Generations that's two to the 20 cell divisions it will have made 4718 mistakes those mistakes can be in the same cell or in different ones as these are all independent events so let's just say for Simplicity sake that they're all in different cells but some of you might argue that that's not always true if mutations are really random then why are these DNA sequencies shared over many generations kept the same even across other species as you've seen earlier and this here is the magic of evolution although mutations can be random the selection process is not random if just one of those mutations hits something that makes the cell survive better gain more resources reproduced more often and so on it usually goes into giving the organism more capability to make more babies in biological lingo this is known as Fitness the other populations won't necessarily go extinct but the population balance will certainly Sway in the favor of the better organism to get back to Shared DNA sequences just like how World War II planes come back with holes in their wings but not their engines it's because all the ones that fell out the sky diey got shot in their engines if that cell gets a mutation that destroys an important trait it will die say no longer able to reproduce more of itself this is known as trait conservation whatever trait that helps a cell reproduce better in its current environment will be selected this process applies to anything that can make more of itself even small molecules like RNA this is collectively known as natural selection it's really similar to an optimization process we start with a random collection of traits within these cells then the mutations create variations in these traits and the traits that help it survive the best get selected and the rest just gets well out competed this is how the system learns a new trait which means that the Next Generation can start another round of enrichment and so on isn't that such an intuitive view of evolution I mean it's just all optimization the problem is if that is all there is to it we would look more akin to hyper optimized eoli than you know what we actually are and this is where nature transforms from just a mechanic that only fixes stuff to an inventor with endless creativity so where does the diversity of life come from to know that please support me on patreon okay okay I'm joking I'm joking but I really do have a patreon though the entire behind the scenes of the video is posted there already so please go check it out and support me thank you it all goes back to DNA replication mismatches aren't the only way DNA can mutate radiation chemical mechanical damages can also alra DNA DNA copying can also be too fast or too slow such that some bases get included or excluded this is one way the 17 bases could have just been deleted our cells have tons of ways to commit an oopsy but most of all the following mechanism I'm about to explain is one of the biggest drivers of diversity The crucial steps of making sex cells or UK carots is fusing two chromosomes together so that they may be brought together to the middle of the cell you might know this as meosis more specifically metaphase 1 a chromosome is just a long strand of DNA that's shaped into this structure using proteins all of your chromosomes together make up your genome the location of fusion is detected by having two very similar stretches of DNA because ideally you'd want the chromosomes to be lined up at the same point the two chromosome can either get shuffled or remain the same and reproduction resumes as usual but sometimes coincidences happen and the other chromosome might have more than two attachment points that means after shuffling one chromosome has its DNA deleted this is known as the deletion event and this is one way 17 bases can also get lost the other has an extra copy of the same gene this is known as duplication and it is one of the biggest ways for nature to invent things the beauty of duplication one copy of the gene can be conserved while the other can mutate into doing other functions one can be a fallback to do the housekeeping function while the other can mutate into doing another function with this strategy there is not much to lose if the Explorer fails there's always a safety net that will catch you this is also one possible way that you can get one of the original machines to diverge and perform very similar reactions it's a very modular and simple way to evolve all of a sudden you don't have to just optimize for one function anymore you can now diversify into various different variations duplications don't occur on just the small scale of genes they can also come from that recopying mechanism shown earlier the whole set of genes can get duplicated by having matching contacts really far away or the whole chromosome can get duplicated by failing to segregate properly this is one mechanism in which pyy can arise just like the baker's yeast shown above in other words it's ingrained everywhere in biology and this isn't even the end of it the there are so many ways in which life became so vastly diverse cells can share DNA with each other they can even work in communities and specializ into different roles nature is such an endless inventure since there are so many mechanisms and possible explanations as to why and how DNA can get modified we decided to use umbrella terms such as duplication indels or mutations to explain away Evolution instead it's not that we can't explain these events because we don't understand how they work or something like that it's just because there are so many ways in which we can arrive at the pattern that it's just better to just use an umbrella term and shove it all under the rug all because of the oopsies that we make when dealing with DNA now even with those mechanisms of evolution there is something beyond that and it will tie back into our snake mice at the beginning of this video there is a certain class of genes known as Hawk genes these genes control the body plan of an animal you can see that across species there are a lot of variants of haxk genes but how do these variations come about but all of this probability or possibility talk might leave some of you quite irritated where are all of the concrete numbers if you want to understand Evolution that way you're going to need a lot of probability and statistics luckily the spor of today's video brilliant.org has a unique and Powerful way to help you get started on that brilliant is where you can learn by doing with thousands of interactive lessons in math data analysis programming and AI the interactives um brilliant help you build your critical thinking skills through problem solving not just memorization which will help you own the knowledge you've obtained so while you're building real knowledge on specific topics you'll also become a better thinker Brant recently launched a ton of new content in data if you want to dig deep into understanding Evolution that way through some of the books I've Linked In description brilliant has the perfect prerequisites for you these courses are perfect for Learners of any level to start or continued learning data analysis with a fully built out suit of new content from base theorem to multiple linear regressions you'll also learn how to parse and visualize massive data sets to make them easier to interpret beyond that you'll also Gain real world Insight by working with real data sets from sources such as Starbucks X Spotify and more to try everything brilliant has to offer for free for a full 30 days visit brilliant.org nanor rooms or click on the link in the description below you'll also get 20% off an annual premium subscription so where do the various forms of Haw jeans come from well let's start with the simplest form from C Elegance you can see that between between it and theof of fruit flies there are a few duplication events these duplications are even more rampant a few more species down the line but these species are both extent meaning they're both alive so why do they look like they've evolved from each other well let's travel back in time to when the duplications happened we've now created two species one of which has an extra Gene that can evolve on its own trajectory but this doesn't mean that both species can't coexist at once this is just like what we saw and yeed earlier that's why both are allowed to reproduce one species has the original setup maybe with changes while the other species has the new setup until this day this is one of the ways that different organisms can share the same control structure note this is not the only way a lot of bacteria can also share whole DN with their neighbors as you've seen earlier this isn't even the highlight of Hawk genes Hawk genes themselves don't directly translate into body parts but they control the genes that go and make those body parts this includes one particular path which controls the expression of Sonic Hedgehog which controls limb formation another part of this recognition sequence called the zap the zrs of snakes is missing the 17 base pairs so the Sonic Hedgehog can't get activated resulting in no limbs Evolution conserves the control structures while modifying the workhorses Downstream creating a mod modular and simple way to evolve so the reason this math scientist experiment works in the first place is an actual reflection of how interconnected we are with other species all of these mechanisms for evolution are essentially mistakes my takea away from all of this is that mistakes allow us to explore more Avenues and not single out on one single method that can leave us stagnant but they have to also be balanced out by a safety net so when we fall we don't break our backs you are a project of a fortunate series of mistakes over billions of years so don't be afraid to make them you might just strike gold one day

Channel: NanoRooms

Views: 68,412

Keywords:

Id: kR7--yt3PRo

Length: 14min 20sec (860 seconds)

Published: Fri May 31 2024