right you home this is chapter 22 our last chapter with this chapter I'm going to really cover stuff that's going to be on the exam so please pay attention we're going to see that and this is important we're gonna see that when Charles Darwin and Russell Alfred Wallace post their idea about evolution be a natural selection it was considered revolutionary all right and the reason for this is that for thousands of years people believed in something known as special creation thinking so what I would say is write this down on your paper right right now so you're gonna have one column and it's gonna say special creation thinking special creation thinking on another column right next to it right population thinking so special creation thinking it's the old way of thinking whereas population thinking is the new way of thinking and it's the correct way of thinking so if you were a special creation thinker you believe in the following things one so under the special creation column you're gonna say one you believe that species do not change they don't change and then two you're gonna write down that species are not related to each other write that down species are not related to each other and then three you're gonna write down that life on earth was young about 6,000 years old all of this not correct all right so special creation thinking which was in place it was popular for thousands of years was replaced by population thinking the new way of thinking the correct way of thinking I would say and population thinking says that one species do change - they say species are related to each other so species are related to each other and then three life on earth is actually old we're gonna find out how all the life has been out or how long life has been on earth we're going to see that evolution and write this down I know you're going to need it for the exam put a star next to this evolution so what is one definition of evolution write this down it's on the exam change in allele frequencies in a population over time so what is evolution one definition of it is a change in allele frequencies in a population over time I know you're going to need that for the exam for sure we're going to see that there's one actor actually for evolutionary mechanisms for ways that evolution can occur we're only going to talk about one way in this chapter and that is by natural selection so natural selection is one of four evolutionary mechanisms meaning it's one of four ways that evolution can occur we're only going to talk about one of the action one of the case studies that's presented in this chapter just in the interest of time so we have evolution what is evolution a change in allele frequencies in a population over time by one of the four mock evolutionary mechanisms known as natural selection so what I'm saying is that natural selection is one way that evolution can occur and both Charles Darwin and Alfred Russel Wallace came up with the idea of evolution by natural selection they were not so they were not the first Charles Darwin was not the first who's who said that species change in fact somebody else said that before him but he was one of the first along with Wallace to say hey I think this is one way natural selection that evolution can occur alright and we're going to see that evolution by natural selection explains how populations can be very well adapted to their own environment so if you put me in the environment of a tapeworm and somebody's gut oh I wouldn't not do very well I wouldn't survive very long because the tapeworm is very well adapted to living in the gut it's got these special hooks to attach to the gut doesn't even need a digestive system because it just simply absorbs nutrients through its cuticle or its skin if you will and recall from the definition of life that one way that we define life is that organisms evolve but here's the key you guys and I know you need to know it for the exam it's on the exam populations evolved one if you say one thing evolved you would be very wrong one thing cannot evolve so species you need to know this for the exam because people miss this question all the time and I was like what the heck is going on and I don't think that students understand that species the word species is plural meaning that I want you to know that species evolved but you me one one of us one individual cannot evolve only populations or species species is plural can evolve Charles Darwin published his manuscript on the Origin of Species by means of natural selection in 1859 when Charles Darwin published this it was considered a revolutionary view it would be like me saying you know what I think smoking is great for pregnant women that was you know that's sort of like a revolutionary statement for decades we've been saying smoking is bad for women pregnant women especially well it's bad overall but don't smoke of you're pregnant so it'd be like me saying you know what smoking is great for the fetus so that's the same impact that Charles Darwin's manuscript had it was considered revolutionary for its time when it was some when it was published the manuscripts sold out in one day all right and recall that theories have two parts there's the pattern those are the observations that you see and there's the process which is the mechanism that's responsible for the pattern that you see so the way I think of it with the cell theory the pattern is hey I noticed that this onion is it was self I noticed that my liver is made up of cells I noticed that all organisms are made up of cells is something that you notice about the natural world and then the process the mechanism that's responsible for the pattern that you see so you would say well for the cell theory all organisms are made up of cells why because cells come from pre-existing cells as I said when Charles Darwin published his manuscript it was considered revolutionary it overturned thinking the old way of thinking which was special creation thinking which had been in place for over thousands of years for over 2,000 years people believed in special creation thinking the old way of thinking the incorrect way of thinking I know for the exam you're going to have to know the names of these individuals and what they're known for when I think a Plato I have to think of well who was he he was a Greek philosopher who said and you need to know you know what did everybody think not only a few names in this chapter Plato believed that species do not change why not because they were created perfectly by a god all right and if you're creative perfectly should you change no you're perfect so I would say Plato believed that species don't change and he believes in something known as typological thinking typological thinking is the old way of thinking it would say a typological thinker would say don't look at the differences among organisms they're not important don't pay attention to that whereas Charles Darwin would say those differences that you see they're very important pay very close attention all right so type of logical thinking is the old way of thinking it was replaced by population thinking the new way of thinking Aristotle what did Aristotle believed he believed that species do not change so he thought the same thing as Plato but he developed something known as the great chain of being be you see it looks sort of like a ladder where he grouped organisms based on increasing complexity alright who's at the very top he thought that humans were the highest organisms and so he placed organisms on a hierarchical scale and that's very wrong we shouldn't do them in see we have jean-baptiste Lamarck what did he believe now he is the first person that we say he said species do change they do change but what he did that was wrong is he proposed that species change over time and they sort of evolved up the great chain of being so maybe he started as a low lower plant then you evolved over time to become a flowering plant over plant over time he became a roundworm over time he became so he saw evolutionists being progressive like you were moving up up up the great chain of being that is not correct and then we have Charles Darwin and Wallace who said you know what don't believe in typological thinking don't believe that differences are not important those differences are very important they say species do change over time but you know what Lamarque also said that species change but what they did is they proposed an evolutionary mechanism that was responsible for evolution what was that evolutionary mechanism natural selection and notice that this phylogenetic tree what you're looking at Indy is a phylogenetic tree and notice what that shows you that plant on the left the fish the I don't know what that is a dog a human a roundworm none is higher than the other they're all like at the same level and that's extremely important what Aristotle did is he developed a great chain of being in yes I think for the exam hint-hint I think you need to know that Aristotle developed the great chain of being what you need to know is that there's no such thing as a higher or lower organism notice how the human is in the same level at the same level as the plant there's no such thing as a higher or lower organism got it in fact let me say this and remember this for the exam put a star next to this comment you are no better than a tapeworm you are no better than a tapeworm I'm no better than a tapeworm basically what that means is if I had to live in the environment that a tapeworm lessened I wouldn't do very well and a tapeworm living in my environment vice versa would not do well so we're all well adapted to our own individual environments so this is just recapping what we saw in that slide Plato who was he a Greek philosopher who said species do not change why should they that were created perfectly if you're perfect why should you change so that's known as typological thinking and Plato would say the differences that you see among different organisms don't pay attention it's not important whereas Darwin would say oh no no no those differences are really important you see that gazelle with one shorter leg than the other that's gonna have a huge impact on that gazelle he's gonna get eaten first and the other gazelles are gonna get to live because their legs are all the same length so Aristotle what is he known for he developed the great chain of being where he plays species on an evolutionary ladder so there were some organisms that were considered higher than others and that is not correct all right of course who did he place at the very top humans and so humans are only surpassed by angels and God so again with Aristotle he said species do not change but what he did is he proposed that some species were higher than others and that is not correct you are no better than a tapeworm Aristotle oops just one second okay so we have aristotle who said that species do not change but again as i said there were some species that were better than others like humans were at the very top but we don't believe that because if I were in the environment of a snake I don't think I would do well slithering on the ground so who was the first individual who set species change it was John Batista Lamarck he said you know what species are Chaney was not Darwin or Wallace who said that species change for the first time it was John Batista landmark now what Lamarque said that was wrong is that he believed that species changed over time and that they moved up the evolutionary ladder the great chain of them we do not believe that all right so he thought he believed in spontaneous generation recall that that's when life begins from nonliving material notice we do not believe in that we believe that cells come from pre-existing cells and what he thought Lamarque thought that again humans were at the very top they were the superior organisms but in reality you are no better than a tapeworm also something else that Lamarck believed in that we should not believe in is inheritance of acquired characters so the example that they gave you in Chapter 1 for this was giraffes are constantly stretching their necks to reach leaves that are way up in the trees as the result of stretching their necks these giraffes get longer necks Isis and that longer neck size will be passed on to the offspring all right so these phenotypic changes the longer next size would be passed on to offspring and the way I would say this no that's not true the alleles the genes that you're born with are those you're going to die with all right I could I could say you know what I have a really flat but I don't like it I'm gonna get a butt implant and you know I could get a bigger butt but guess what what kind of butt would my children get a very flat one because those are my alleles I have a flat butt oh my my poor husband flattered but that means that the diapers would just slide off those babies so Darwin and Wallace believe that species did change over time they were not the first one to say this remember Lamarck also said that species changed over time but unlike Lamarck they did not believe that species followed a linear or progressive pattern and also what they said was those differences those variations that you see among individuals in a population pay very close attention to that it's very important here's the definition for population individuals of the same species living in the same area at the same time and this is important they're going to be individuals with certain traits that will produce more offspring than others without that trait so this is natural selection my example is the following let's say enough useth before let's say we're all male birds in nature who gets the females who attracts the females it's the really bright color for colorful birds the really bright ones so let's say I was born as a bird with really bright colorful feathers like more colorful than my other males guess what I would be the male that the females would be selecting I would be the one that would be breeding more than the more drab males as a result what's gonna happen to the population I'm gonna be the one breeding the babies gonna are gonna look colorful like me and now you're gonna have evolution what is the definition for evolution that you need to know for the exam a change in allele frequencies in a population over time as I said population thinking is the new way of thinking it is the correct way of thinking typological thinking is the old way of thinking the incorrect way of thinking and so again Darwin said those differences those variations that you see among individuals are very important you see that really bright colorful bird there that's important that could lead to evolution because he's going to be the one that's anymore as a result the allele for colorful feathers is going to increase in the population over time so as I said before the theory of evolution by natural selection was revolutionary it overturned thinking that was in place for over 2,000 years it overturned special creation thinking so typological thinking the old way of thinking was replaced with population thinking the new way of thinking it also said that species do change they don't stay the same and the nice thing is that evolution is scientific you can design experiments to test evolution if you were to take the second part of this course you would see different experiments that have been done with computer models and natural populations etc Darwin described evolution as descent with modification meaning we descended from our ancestors with changes modifications changes and those changes led to modern modified species so the pattern component of the theory of evolution by natural selection predicts that one you're gonna see that species change over time and two we should see that species are related to each other by common ancestry you may find this hard to believe but guess what we all descended from something that looked like a naked cell meaning didn't even have a plasma membrane alright remember the first life molecule we think was an RNA molecule meaning that all life on Earth your sea horses your killer whales your redwood trees descended from that one molecule this is the part of evolution that a lot of people have a hard time understanding or believing in the idea that we're related by common ancestry but we're gonna see lots of data that does support this there's tons of data that being said we have a lot of people especially in the US who just have a problem with evolution they seem to think that it contradicts religion but you guys you can be religious and still believe in evil lucien i promise you what are fossils any trace of a living organism that any trace of an organism that lived in the past it could be the tracks of a mammal it could be the poop of a fish i mean it's any trace of a living organism and the fossil record is made up of all the fossils that have been found and described we're gonna see that there's there's fossils that are being maintained in public public museums there's some private collections all of them make up the fossil record extant species what are those those are species that are still with us and they are the modified forms of a Suns ancestral species alright so here is the next few slides are going to tell you the following one species have changed over time that's what they're gonna tell us so that's what they're prepping us for right now so we're gonna use relative age of fossils to show how species have changed over time how do we get fossils they tell you that sedimentary rocks form from sand or mud that gets deposited in layers if you find a fossil and it's further down in the in the sedimentary rock that's an older fossil relative to a fossil that's found further up or closer to the to the surface of the ground so we can assign relative ages to fossils based on where we find the fossil within your sentiments if your fossil is way further down we're gonna say that fossil is older relative to a fossil that that's found closer to the surface of the ground we had the geologic time scale you guys this is a huge amount of time it's hard for us to picture how much time Earth has existed in life on Earth they say if you were to put humans on Earth or let's put it this way if you were to have the entire history of life on Earth be 24 hours like on a clock when did human finally arise an hour before midnight so I mean think about it for the most of that time there were no humans on earth basically they're trying to tell you this is plenty of time to show that that life has sorta to show that species can evolve from each other so that we can get something as beautiful as a seahorse or something as ugly as a cat okay I'm sorry y'all I just don't like cats and so them the relative when we look at false as they show us that earth life on Earth it's much older than 6,000 years old you guys how old is Earth four point three billion years old you guys billion that's huge a slide to show us what's what relative ages of fossils means notice that at the very bottom we have a trilobite that fossil is much older than the fossil that's closer to the surface and we're assigning a relative age to the fossil just based on where we find it within the sediments the deeper down the older the fossil in addition to this we can assign absolute ages to fossils using using radioactive decay of certain elements I'm not gonna hold you responsible for this but just know that I can find a fossil and use the sediment that is found in and say boy that fossil I can assign an absolute age to that fossil I can say that fossil is three million years old as I said how old is Earth about 4.6 billion years old plenty of time for species to diverge from each other to look to give us the different life forms that we see on earth now when that life on earth began about 3.5 billion years ago billion years that's a huge long time extinct species are those that are no longer with us like the dodo bird like the like the saber-toothed tiger and so Darwin said hey the fat we have extinct species tells me the species are dynamic they're changing so that contradicts which two individuals contradicts Plato contradicts Aristotle cuz both Plato and Aristotle said species don't change why should they they're perfect and y'all that's a scary bullet point right there do you see it over 99% of all species that have ever lived are now extinct Wow in fact there have been five mass extinctions on earth one of them the end-permian extinction practically wiped out life on Earth permanently we're lucky to still be here here we see some well that's definitely not something we've seen in many many years so that's a dinosaur that went extinct look at the size of that guy so we have said yes species have changed over time we have extinct species in fact over 99% of all species that ever lived on earth are no longer with us what is else supports the idea that species have changed what else contradicts Plato and Aristotle who said you know we don't think species change you they're wrong we have transitional features these are traits that are intermediate that are in between the ancestral and the derived species so they're documenting changes over time so this data supports predictions made by the theory of evolution and rejects the idea that species do not change so notice here we're looking at the development of the tetrapod limb what does that mean we have tetra for appendages so how did the appendages arise believe it or not we think that the appendage of the legs came from a modified fin like fins used for swimming so you have your older fossil at the very bottom notice he's a swimmer he's got fins over time what happens notice that the bones are being arranged slightly differently we still have the same number of bones we had the humerus and blue we have the ulna and the radius in red we have the distal elements they're just being arranged differently so we can get a limb that's adequate for moving on land from motion on land what's more data that supports the idea that species have in fact changed are still changing the schedule traits and you guys are gonna have to identify what's a vestigial trait on the exam you're gonna be given different examples and so a quick way of finding out which is your vestigial trait is it's a trait that's fully formed fully functional in one species and poorly develop not fully functional in another species that's your vestigial trait and don't worry we have plenty of examples of a stijl traits again what's your vestigial trait fully formed fully functional in one species poorly developed not functional in another closely related species these vestigial traits are not consistent with the idea of special creation in fact they're saying you know what species have changed over time what are examples of vestigial traits again look at this slide very closely because on the exam you're going to have to identify which of these four is the vestigial trait example they tell us that some whales and snakes have tiny hip and leg bones they don't do anything they're not involved in swimming or slithering why are these whales and snakes stuck with these tiny hip and leg bones well at one point their ancestors had appendages had legs we have ostriches and Kiwis these birds they have reduced wings they cannot fly they're not functional why are they stuck with these little ridiculous wings well because at one point their ancestors could fly we have blind cave-dwelling fish they live in very dark caves where no light penetrates they have eye sockets but no eyes what happened with that well if you're stuck in a dark cave do you need so you lose them over time and you still have the eye sockets another example of a vestigial trait again and a vestigial trait look for a trait that's poorly formed poorly developed in one species fully formed fully functional in another species humans we have the tailbone right does it do anything for us no but there are tails and closely related species we're very closely related to monkeys and their tail is fully formed fully functional it's used to for balance and also to grab on to tree limbs so you see here an example of a vestigial tree again the human --ax the vestigial trail tail it's poorly formed poorly developed not fully functional doesn't do anything for humans and then on the left he had the spider monkey tail fully formed fully functional used to for balance and used for grabbing on to stumps of trees vestigial trait this shows us that species have changed over time and currently we see changes occurring in front of our very eyes we see we have a huge problem when it comes to antibiotic resistance in bacteria think of MRSA methicillin-resistant Staphylococcus aureus Staphylococcus aureus is a bacterium unfortunately it's resistant to many antibiotics including methicillin another example would be the evolution of beak shape and finches I'm going to skip that example in the interest of time but they tell you evolution can be seen on the scale of days weeks and months not just millions of years this you might think Charles Darwin at one point was considered a failure he wanted to be he wanted to go to medical school but just didn't get the grades and so he would spend lots of time speaking to his professors I think they were just sick of him wanted to get rid of him they said hey Darwin there's this voyage this ship that's going to travel to the Galapagos Islands and they need a naturalist are you interested in the job now the job had been offered to others nobody took the because hey didn't pay but he was lucky in the fact that he came from a wealthy family he said you know what I'll take the job and that's how he developed his manuscript which made him one of the founding fathers in biology so you think you're a failure at one point can't get into medical school and then before you know it you're a huge success your your name is known for decades dude not decades for four oh my gosh I can't think of hundreds of years all right let's get that cuz I'm just tired so this is during this voyage on the HMS Beagle the name of the ship Charles Darwin was able to collect data that he used in order to manuscript to to write his manuscript he saw a pattern when he saw he saw descent with modification so he saw the current species descended from their ancestors with changes modifications he noticed that when he looked at mainland Birds they look similar to birds that were found on the different Galapagos Islands so he found different species of mockingbirds he knew that they were different species but boy they sure look similar to each other so what could explain that so his idea was that all these mocking birds were similar because they descended from the same common ancestor a mainland bird notice in Ecuador mainland birth that somehow these birds were thrown off course landed on the different Galapagos Islands the different Galapagos Islands have different fauna different trees different seeds available so over time these birds diverged to become different species of mockingbirds so when you look at Mockingbird DNA data or actually Finch DNA data guess what it supports this idea you get a phylogenetic tree which shows that these birds share a common ancestor that arrived about one and a half million years ago so we see descent a common ancestor with changes so they're in red on the red portion we see the common ancestor of all the Galapagos finches they all look similar but there are differences why do they look so similar they descended with changes from the same common ancestor why did they change the different Galapagos Islands have different fauna different vegetation some have trees some have more arid looking places this is on the exam for sure you need to know what homologies are homologous or similarities that exist due to shared common ancestry homology similarities that exist due to shared common ancestry on the exam you're gonna have to tell me are you looking at a genetic developmental or structural homology there's three different levels and y'all I gave you this exam question multiple times because it's easy to answer a genetic Amala G is similarities that are seen in the DNA RNA or amino acid sequence developmental homologies look for one word embryo developmental homologies are similarities that are seen in the embryos we're gonna see examples of this and structural homology are similarities that are seen in adult morphology similarities that are seen an adult morphology again this will be on the exam put a star next to this one make sure that you know make sure you know this one as I said genetic homologies are similarities that are seen in the DNA RNA or amino acid sequence level and here's an example we have the aniridia gene in humans and the iowa's gene and fruit flies this gene and both organisms dictates where the eye will form and the different letters are just different amino acids each letter stands for a different amino acid notice that the amino acid sequence genetic homology is quite similar Queen humans and the fruit fly even though once an invertebrate and once a vertebrate why are they so similar yell now we're looking at the data that shows us that we descended from a common ancestor so before all the data the transitional features the fact that species have gone extinct the fact that we have vestigial traits all of that was the data that showed us hey species have changed here we're looking at the data that shows species are related by common ancestry you would not expect to see homologies if we were not related to each other now let me ask you this do you remember who said we're not related Plato and Aristotle developmental homology look for one word embryo developmental homology are similarities that are seen in embryos for example this is going to blow your mind we have early Chik human and cap embryos and they all have tails at one point along with Ferengi allow as yes you and I at one point during our embryonic development how to tail inferential pouches the pouches will turn into gills in aquatic organisms you don't have a tail now do you although I do worry sometimes when I see certain people mm-hmm they might have a tail so here's proof we have a chick we have a human we have a housecat the little yellow circle shows you the foreign jold pouches those are the ones that will develop into into into gills in aquatic organisms and there's the tail all of us had a tail at one point why do we see these similarities in the embryo these developmental homologies because they share all of them shared a common vertebrate ancestor one with a backbone structural homology these are similarities that are seen an adult morphology the example that were given is that most vertebrates have a common plan when it comes to their limb bones most vertebrates have the same number of bones they're just arranged slightly differently notice here we have different appendages different limbs we have a human arm what do we use our arms for we use it to raise things to lift things right a horse uses his appendages to trot or to run birds and bats fly and seal swim so we have different appendages that are adapted for very different uses but notice in all cases we all have one humerus in blue that bone we have the radius and the ulna in red and we have the carpals notice that we're just arranging the bone slightly differently so that they can be used for different types of movement again what you need to know similarities an adult morphology or an example of structural homology so you need to know that because I I know I give you two examples on this a nice little summary is coming up that shows us what is the proof for the fact that species have changed remember species plural you're going to need it for the exam species is plural speciation that is when one species splits on and splits off into two or more descendant species we see that killer whales seem to be undergoing speciation one killer whale is going to lead to two different species of killer whale so some populations of killer whales are so different in what they choose to feed on their prey and their social behaviors how they hunt some of them hunt together some hunt alone that they no longer interbreed with other populations of killer whales that means they're moving on towards becoming different species nice little graph or table that shows you what is the data the supports that species are changing or have changed and what is the data that shows that species are related by common ancestry very good there's something known as internal consistency which occurs when you have multiple data sets from many different sources that all that all support the same conclusion that species have in this case descended from our ancestors with modifications or changes so there's tons of data from many different sources we're not making this up out of nothing not out of thin air we have plenty of data that shows that yes in fact species have changed over time we descended from our ancestors with changes with modifications an example of internal consistency data from many different sources that support the same conclusion is seen with cetaceans what are situations these are whales and dolphins which have a very unusual they have an unusual ear bone a'right the fossil record shows that oh there it is they have very unusual ear bones we see that the fossil record of cetaceans shows that there has been a gradual change between terrestrial and aquatic forms what are they trying to say you guys are not gonna believe this but the closest living relatives to today's whales are hippos yep closest living relatives to today's whales or hippos why they share a common ancestor that was semi-aquatic and hoofed but whales don't have legs they don't have appendages but yes they descended from the same common ancestor ask the hippos we have internal consistency what does I mean data from many different sources that all supports this this conclusion we have relative dating of fossils remember that's when you use the position of the fossil to assign a relative age to the fossil meaning that if this fossil was found further down in the sediments it's older relative to a fossil that's found further closer to the surface of the earth when we look at DNA sequence data we see that hippos are the closest living relative to cetaceans or our whales and dolphins and then BOOM more data from another different type of source we see the schedule hip and bones found in some adult whales and dolphin embryos why are they stuck with these little tiny bones that are not functional well at some point their ancestor had fully formed appendages that were lost so here we see the gradual transition with a sort of creepy the top one hoofed and semi-aquatic that was the ancestor to today's hippos and modern whales and you see as we go over time there's a gradual change from an organism that let go from top to bottom notice that the very top organism looks like he walks on land the second one looks like a land Walker also third one looks like a swimmer fourth one looks oh man you lost your appendages there so we have not just DNA sequence data not just the vestigial hip and leg bones that are found we also have the fossil record all of this is data from many different sources that all support the idea that whales shared a common ancestor with hippos what was the ancestor like it was hoofed and semi aquatic as I said data from many different sources are much more consistent with evolution they support the idea of evolution but then they do with special creation because if you believed in special creation thinking you said species don't change why should they question who believed species do not change you better say Plato and Aristotle descent with modification therefore based on all this data it's a more successful in powerful scientific theory there's tons of data from many different sources that shows that species have in fact changed over time the hat the fact that we have vestigial traits show that species have changed over time they do not support the state of does not support special creation thinking all right