Smoove_B was the first mammal to wear panties

[Guy Incognito]

Forgot the original poster (RM9 should know) but pasting this here because it needs to be saved for future generations!

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INTRODUCTION

This is my attempt to explain, in simple terms, some of the evidence supporting evolution. It is not, by any means, exhaustive. This is designed to be a message board post and not an article, and the writing style reflects that (no long paragraphs, etc). What I’ve done is to discuss a few lines of evidence that I know something about and which I find compelling.



My goal in writing this was not to upset anyone, but I am critical of creationism in this post. So, if that’s going to upset you, you might not want to read any further. My goal here is just to try to replace disinformation with fact. If anyone finds any factual errors in this article, or if any part of this post is difficult to understand, please speak up and let me know. My only request is that any such criticism be constructive (saying nothing but “Gebeker you are wrong” isn’t constructive).



I realize that this post is extremely long. If it’s just too long for you to read all of it, I’ve divided it up into sections, with each section clearly titled in all capital letters. That way, you can read only the parts that interest you if you don’t want to read the whole thing. If you don’t know what a point substitution mutation is, you should probably read the first section, though, because some of the other sections won’t make any sense if you don’t. However, if you have an interest in evolution/creationism, I encourage you to read the whole thing through.



In general, I try to discuss creationist arguments in each section. In a few cases, though, I felt that my response to the creationist arguments might bog down the discussion and/or distract the reader from important points. In these cases, I’ve discussed the creationist arguments at the very end of the post.



EVOLUTION- MECHANISMS AND BACKGROUND INFORMATION

This introductory section is designed to give the absolute minimum amount of information necessary to understand the rest of the post. A proper introduction to these issues would take far too much space in an already very long post.



First, I will describe the mechanism by which evolution happens. Charles Darwin’s idea was that natural selection (survival of the fittest) can act on existing individual variation to cause lasting changes in a species. Over time, he reasoned, this process can lead to very large changes. At that time, Gregor Mendel still hadn’t done his work on the principles of inheritance, and most of the work on DNA would come over a century later. So, Darwin didn’t have a very clear grasp of what caused differences between individual organisms. However, he did get the basic idea right.



Natural selection is a powerful and simple idea that is based on a few observations:



1. Within a species, individual organisms will differ from one another. (Clearly observable fact – you are different from your parents, your neighbors, and everyone else on earth.)



2. Some of these traits tend to be inherited.



3. Some traits will be favorable, others unfavorable. The ability to run fast is favorable for a cheetah, for example. Being born with a muscular defect is unfavorable. (This is common sense.)



4. Organisms with favorable traits will be more likely to survive long enough to reproduce than organisms with less favorable traits. (This is common sense.)



5. Therefore, over many generations, favorable traits will tend to spread through the population, while unfavorable traits will not. (Common sense, given 1-4, above.)



As the environment changes, a species will tend to adapt to meet the new requirements for survival. In fact, this is such a simple, common sense idea that most creationists don’t argue with it at all. Instead, creationists generally accept natural selection, but argue that it can only lead to small changes (i.e. microevolution). Different creationists have different ideas on where they think the limit is. Many think that the evolution of new species is impossible. Some accept the evolution of new species, but reject the idea that evolution can lead to bigger changes, such as the evolution of humans from apes.



A common creationist claim here is that natural selection tends to REDUCE genetic variation (and, to some extent, it does). Since evolution predicts an increase in the diversity of life, they argue that natural selection actually works against evolution. Therefore, the claim goes, evolution by natural selection is absurd. Of course, even in Darwin’s day, it was known that natural selection was only part of the picture. If evolution is going to work, we need a powerful source of genetic variability. In other words, natural selection needs something to act on. That leads us to the other part of the mechanism driving evolution: mutations.



There are actually several sources of genetic variation, including mutation, DNA recombination (from sexual reproduction), and gene flow (an organism moving from one local population to another, bringing new genetic variation with it). For purposes of this discussion, mutation is the most important.



Humans have 46 chromosomes, in 23 pairs. For each pair, we get one from our mother and one from our father. Other species have different numbers; some have more and some have less. Each chromosome contains many genes, as well as a collection of nonfunctional DNA, including formerly active genes that have been rendered nonfunctional by past mutations (more on that later).



Genes actually code for proteins. Proteins are composed of (long) sequences of amino acids. A change in the sequence of amino acids changes the protein. The effects of this change on the function of the protein will depend on exactly what the change was, and what part of the protein was altered. It may completely destroy the protein’s function, it may have no effect, it may improve the protein’s function, or it may even give the protein a completely new function.



Genes are composed of long sequences of simpler molecules called nucleotides. The famous “double-helix” structure of DNA is like a twisted ladder. This shape exists because each nucleotide in one strand is chemically bonded to a particular nucleotide in the complementary strand. So, the term “base pair”, refers to the nucleotide in one strand and it’s “partner” in the complementary strand. The chemical bonds between nucleotides and their “partners” in the other strand are like the rungs of the ladder.



The four nucleotides that are found in DNA are given letter designations: A, G, C, and T. These nucleotides are like letters in a molecular alphabet. A sequence of three nucleotides is called a “codon”. Each codon represents one amino acid. So, if the nucleotides are like letters, the codons are like words. In addition to the codons that code for amino acids, there are “start codons” and “stop codons” that tell the cell where to start and stop when “reading out” the gene to make a protein. Each amino acid can be coded for by any of several (the average is three) different codons. This fact is important for some of the later discussion.



Whenever a cell divides, a copy is made of the DNA. Occasionally, a copying error will be made. These copying errors can take many forms, but one of the most common is called a point substitution. A point substitution mutation simply replaces one of the nucleotides (and, of course, its partner in the complementary strand) with a different one. Usually, this will mean that the proteins made from the daughter DNA strand will have a different amino acid at that location. This type of mutation is also referred to as a “single base pair substitution”.



Point substitution:

“The dog bit the hat.”

“The dog bwt the hat.”



In this analogy, each word represents a codon. Each letter is a single nucleotide (complementary strand is not shown). Sometimes the change is bad for the organism, sometimes it’s neutral, and sometimes it’s good. Where this analogy breaks down is that there are very few neutral “mutations” that could occur in the above sentences. Almost any change you could make would be bad. In nature, there are many point substitution mutations that are neither beneficial nor harmful. One potentially favorable “mutation” exists in the above sentences – you can change the “h” in “hat” to a “c”.



Other kinds of mutations also occur, including insertions of one or more nucleotides into the sequence, deletions of one or more nucleotides, inversions (in which a sequence is reversed), and more. Sometimes a portion of a gene, an entire gene, or even an entire chromosome, can be repeated. Gene duplication is particularly important, because it’s a good way for organisms to evolve entirely new genes to serve novel functions. First, a mutation creates a duplicate copy of a gene, then subsequent mutations alter one of the copies so that it becomes a different gene serving a new function. This process can result in large families of genes that are all derived from a common “ancestor” gene. Evidence of every part of this process can be seen in nature. Evidence of gene duplication and subsequent divergence is easy to find in the scientific literature.



Proteins are made up one or more structurally and/or functionally distinct portions known as domains. In addition to duplications of entire genes, mutations can duplicate the genetic sequences coding for domains. Recombination (from sexual reproduction, for example) can lead to new proteins by creating new arrangements of these domains.



Finally, it should be mentioned that some genes (referred to as regulatory genes) regulate the expression of other genes. Often, a single gene can switch large groups of other genes on or off. Mutations in these regulatory genes can often change the conditions under which proteins are made from other genes. In turn, this can result in large changes in the organism. This is particularly important in fetal development. In most primates, for example, brain growth is essentially finished at birth (although refinements in the circuitry, of course, continue). In humans, however, the brain continues to grow long after birth. Brain growth is controlled by regulatory genes that switch other genes on and off at the right times. In the course of hominid evolution, mutations in some of these regulatory genes evidently altered the timing of expression of other genes coding for proteins that begin or end various aspects of brain growth. The result? A bigger, more complex brain. Within the next 10 to 20 years, research should isolate many of the exact genes and mutations that were involved in this process.



EVIDENCE FOR THE EXISTENCE OF FAVORABLE MUTATIONS.



Creationist J.G. Leslie at Answers in Genesis writes:

"No known mechanism of mutation, either at the gene level or the chromosome level has been discovered which will produce evolutionary advancement. This is particularly so because all molecules involved in replication (DNA, RNA, protein) are interdependent with each other, and do not function in isolation. In other words the cell and its genetic contents, give the appearance of having been an initially created complex unit ready to work. That is why any subsequent random mutational changes to it have been and are observed to be deletarious."



Leslie is badly mistaken. Note that he claims that all mutations are harmful. As any biology undergraduate student should know, this claim is ridiculous. Just to take one quick example, there are over 250 completely harmless single amino acid substitutions that have been found in human hemoglobin (Voet and Voet, 1995). In fact, minor, harmless differences in the sequences of genes are what make us all look different from each other in the first place.

So, is there evidence that favorable mutations occur? Yes. Beneficial changes to DNA sequences have been demonstrated many times, both in nature and in the laboratory. I’ll give just a few examples:



Antibiotic resistance is one well-known example. Resistant strains of bacteria generally evolve very quickly when a new antibiotic is developed. There is a constant race between researchers and evolution. In many cases, resistant strains of bacteria start showing up within 3 years of FDA approval of a new antibiotic (BG Hall, 2003). This is a major concern among medical researchers today, because evolution seems to be winning this race. Some strains have even become resistant to multiple antibiotics.



Creationists sometimes respond to this by claiming that all of the resistant strains were created by God during creation week. In other words, they argue that natural selection is simply acting on strains that have always existed. However, this is clearly not the case, for several reasons. First of all, if this were true, all we would need to do to “win” would be to design ONE synthetic antibiotic that there wasn’t already a resistant strain for. I suppose one could argue that God knew we would one day develop antibiotics, and so He created resistant strains for all of the antibiotics that might be developed. A big problem with this, though, is that many of the resistant strains are slightly inferior to the non-resistant strains in the absence of antibiotics (BG Hall, 2003). The resistant strains are usually better only in the presence of antibiotics. For the creationist argument to hold up here, ALL of those resistant strains would have had to survive for thousands of years, even though natural selection favored their elimination.



There is an even more fatal problem with the creationist argument, though. The fact is that biologists have evolved resistant strains in the laboratory (Hall, 2003a, b). They carefully select only a single (nonresistant) strain to begin the experiment. Usually (but not always), these experiments use techniques that increase the rate of mutation. This is done simply because of the need to complete such experiments within a reasonable amount of time. It turns out that antibiotic resistance usually comes about through a series of favorable mutations, each one of which can be identified, observed, and isolated in the laboratory. Here, creationists are likely to complain that the biologists are doing something “unnatural” in these experiments, and that these same evolutionary steps would not occur in nature. However, all the researchers have done is increase the rate at which mutations occur. Since mutations are random events, they haven’t caused anything to happen that wouldn’t happen in nature (remember, also, that some experiments have been performed without the use of any techniques that affect the mutation rate).



Just in case the above argument doesn’t convince you, biologist Barry Hall, at the University of Rochester, has dealt the creationist argument another serious blow in recent years. He has evolved the resistant strains in the laboratory, and then reconstructed a precise sequence of point substitution mutations that could occur between the original (non-resistant) strain and the evolved (resistant) strain. Each mutation in the sequence makes the bacteria a little more resistant to the antibiotic, until the fully resistant strain evolved – right there in the laboratory. In recent years, Dr. Hall has been doing some exciting work that is allowing us, for the first time, to be able to use evolutionary theory to predict the evolution of antibiotic resistant strains before the antibiotic is even used on patients. Understanding and predicting the exact sequence of evolutionary steps involved in antibiotic resistance may allow researchers to design new antibiotics that are hard to evolve resistance to.



Viruses also evolve new strains to beat our antiviral drugs. One example has been seen with drugs used to treat HIV infection. In 1996, a new class of drugs was developed that block a key enzyme that the HIV virus needs to reproduce. Patients taking these drugs showed dramatic delays in the onset of AIDS symptoms. For a while, things looked very promising. However, over months or years of taking the drugs, their effectiveness decreased. The virus was evolving new drug-resistant strains within the bodies of the patients. This was no pre-existing strain that was created by God 6000 years ago. This was a NEW strain that evolved right there in the bodies of the AIDS patients. It had to be a new strain, because the drug had been effective in the same patient for months. Again, the precise mutations involved are known.



Insects evolve resistance to pesticides. Many such insecticides use chemicals known as organophosphates and carbamates. These chemicals block an enzyme known as acetylcholinesterase. At the junction between muscle fibers and the nerve cells that drive them, a neurotransmitter called acetylcholine is used. The acetylcholine is released by the neuron, and it diffuses across the small space (called a synapse) between the neuron and the muscle cell. Then it chemically binds to receptor proteins and initiates a series of chemical reactions that cause the muscle to contract. The enzyme acetylcholinesterase breaks down the acetylcholine after it has been used, which gets it out of the synapse. Without this enzyme, the acetylcholine hangs around too long, which causes paralysis because the muscle cell’s receptors get overstimulated.



The organophosphates and carbamates in the insecticides block the insects’ acetylcholinesterase, so the insects become paralyzed and die. It’s a pretty effective idea, but evolution comes to the insects’ rescue. They evolve resistance to these insecticides. Recent work by Mylene Weill and colleagues has identified the mutation involved in the evolution of resistance to insecticides in mosquitoes. It turns out that a single point substitution mutation changes one of the amino acids in the acetylcholinesterase enzyme. This changes the enzyme molecule’s shape in a way that prevents the organophosphates and carbamates from interacting with it. Result? The insecticide no longer works on the mutant insects. Note that the mosquitoes only need a single mutation to become resistant to the pesticides. Given the known rate of mutations and the size of insect populations, this favorable (for the insects, not for us ) mutation MUST occur. It is virtually a mathematical certainty that these insects will eventually evolve resistance to these pesticides. So, it’s not just a case of a pre-existing variety of mosquitoes created by God during 6 days of creation.



In humans, many of the descendants of one individual in 18th century Italy carry a mutation that gives them a very great resistance to atheriosclerosis (clogged arteries). Persons that carry this favorable mutation show dramatically lower levels of atheriosclerosis than the general population, even at an advanced age. The mutation improves the function of a protein known as Apolipoprotein-AI. The “un-mutated” version of this protein helps to remove cholesterol from cells and prevent clogged arteries (atheriosclerosis). The mutant version is a more effective protein that prevents heart disease in at least two ways. First, the mutant protein has an improved ability to remove cholesterol from cells. Secondly, the mutant version of this protein has highly specific antioxidant activity that the un-mutated version does not have. So, here is a favorable mutation in humans, and we know exactly when and where the mutation first occurred. Here is a journal article that establishes the origin of this mutation.



As mentioned above, favorable mutations have been observed many times in the laboratory. Whole new biochemical pathways have evolved in bacteria in the laboratory (BG Hall, 1982). This experiment was performed without the use of any techniques that affect the mutation rate in any way. The evolution of the new biochemical pathway required a sequence of several mutations within a few weeks. Link



Here are a few more examples that I found in a brief search of the recent scientific literature:



A recently discovered favorable mutation in humans that protects against malaria.



http://www.ncbi.nlm.nih.gov/entrez/quer ... t=Abstract



http://www.ncbi.nlm.nih.gov/entrez/quer ... t=Abstract



http://www.ncbi.nlm.nih.gov/entrez/quer ... t=Abstract



Note that some of the mutations described in this section create whole new functions for biological molecules.



At this point, some creationists would complain that everything I’ve described so far is “microevolution”. In other words, they concede that small changes like these are possible, but major changes (macroevolution) are not. In other words, they claim that species have a limited ability to adapt, but the kind of major changes that evolutionists believe in are not. For example, they would not accept the evolution of humans from apes, because they believe that mutation+natural selection are insufficient to do that.



According to one version of this claim, favorable mutations are possible but only because it is sometimes advantageous to destroy existing genetic information – mutations that increase genetic information are argued to be impossible. For example, consider the blind cave fish. In some caves, there are fish that live in bodies of water within the cave. These fish generally live their entire lives in total darkness. For these fish, eyes and body coloration are unnecessary. These fish have degraded, nonfunctional (vestigial), eyes, and their scales have usually lost their color. In some cases, these blind cave fish are of the same species as “normal”, sighted, colored fish living outside the caves. This is important, because even creationists must admit that the blind cave fish and the sighted fish outside the caves came from a common ancestor, since they are the same species. Some creationists concede that these adaptations (which are, after all, large body changes) are possible because a mutation has destroyed genetic information in a unique situation in which the loss of that information is favorable. Conceding that favorable mutations are possible allows them to respond to examples of favorable mutations by trying to put a “spin” on the story to make it sound like a loss of genetic information.



Notice, however, that many of the examples given in this section clearly do not fit this idea. The APO-AIM mutation in humans (the atheriosclerosis one) clearly enhances the existing function of the protein, and even gives the protein new functions that it didn’t have before. The Barry Hall (1982) experiments involved the evolution of an entirely new biochemical pathway in the laboratory, involving three separate mutations. In some cases, experimental evolution in the laboratory has shown entire sequences of favorable mutations, with each one improving the function of an enzyme. Clearly, these favorable mutations have nothing to do with a loss of genetic information. How could anyone deny that a mutation that creates new functions for a gene/protein increases genetic information? How could anyone deny that the evolution of a whole new biochemical pathway represents an increase in genetic information? How could anyone deny that gene duplication followed by subsequent divergence constitutes an increase in genetic information? Creationists can deny it because usually the only people that know better are those that have spent a lot of time studying biology. That means that the creationists’ arguments will sound very compelling to most people.



Let’s return to the blind cave fish for a moment. These fish have often been the “poster boy” example of the creationist “mutations can only destroy genetic information” argument. Traditionally, it has been thought that the degenerated eyes in these fish were the result of a mutation that inactivated one or more genes involved in the embryonic development of their eyes. Recent work by William Jeffrey at the University of Maryland has shown that this is not the case. Dr. Jeffrey has shown that all of the genes necessary for eye development are still present. After years of painstaking work, every single one of these genes seems to be in perfect working order. So, why don’t the fish have eyes? It turns out that eye development starts normally, but then the cells simply start to die by a process known as apoptosis (programmed cell death). The apoptosis occurs because of mutations that have created new genetic instructions that cause apoptosis to occur in areas where it didn’t before. In other words, no genetic information has been lost. It turns out that mutations have caused overexpression of a gene called Sonic Hedgehog (yes, that’s the gene’s name). Jeffrey and his colleagues tried overexpressing this gene in populations of fish that normally have eyes. This caused some interesting effects, including loss of the eyes, an increase in the number of taste buds, and a larger mouth. It’s easy to see why this would be beneficial to a population of fish living in total darkness.



Hmmmm, overexpression of the sonic hedgehog gene causes total blindness, strange tastes, and a big mouth. Maybe scientists have discovered the molecular basis for what’s wrong with most congressmen.



THE FOSSIL RECORD AS EVIDENCE FOR EVOLUTION



In some parts of the country, it’s common for sections of highway to be cut through a hill. Have you ever noticed the hillsides where the road cut was made? The rocks will often be arranged in obvious layers. Each layer will often look very different from the one above it and the one beneath it. (Maybe the best place of all to see this is the Grand Canyon.) These layers exist because the rocks were laid down and formed over time. In general, the uppermost layers are the most recent. (The earth is a geologically active planet, so occasionally a sequence of layers can be flipped over – whenever this happens, there are geologic signs indicating that this has happened.)



Long before the days of Darwin, people had already noticed some interesting things about these rock strata. In England in 1794, a man named William Smith was in charge of constructing what would one day become the Somerset Canal. Needless to say, someone in charge of such a project would see all the rock layers he could ever hope to see. Smith noticed that the particular rock layers were so consistent that he often knew what layer the diggers would uncover next, even before they had dug down to it. Even across great distances, he kept seeing the same rock layers in the same order. Even more amazingly, he noticed that each layer had its own particular set of fossils. While some fossils were found in more than one layer, the particular set of fossils that could be found in any given layer was fairly predictable. There was an orderly progression of fossils found in the different layers. Note that this wasn’t an observation made by an evolutionist – Charles Darwin had not even been born yet.



This orderly progression of fossils in different layers of rock is exactly what we would expect to see if evolution is true. Over millions of years, environmental conditions change. As a result, the rock layers that are formed in any given area change their look over time. As time passes, new layers are laid down on top of the older ones. The lower down we go, the older the fossils will be. Different fossil species appear at different times, and the order of appearance of various fossil species makes logical sense. Bacteria are found long before multicellular organisms. Invertebrates are older than fish. Fish are older than amphibians. Amphibians appear after fish. Then you have reptiles. After reptiles, then you see birds and mammals appear. In the absolute most recent layers, you start to find humans. A similar progression can be seen for plants.



This orderly progression of fossils in the different layers is a tough one for creationists to explain. Young earth creationists claim that fossils were formed in Noah’s Flood. According to this idea, the various layers exist because, during the Flood, sediment settled to the bottom at different rates. The heaviest particles of debris would sink first, and the lightest last. The result, supposedly, would be the neat, consistent, layered pattern we see. Why does each layer have its own set of fossils? The creationist explanation here is that more mobile, intelligent animals would escape the rising Flood waters the longest, and so their fossils would be found in the uppermost layers. Humans, being the smartest, would escape to the highest ground of all, and would survive the longest. So, human remains would only be found in the uppermost layers of all. At first, it sounds like a pretty reasonable argument.



However, when you take a close look at the fossil record, problem after problem shows up for the creationist explanation. Did the humans take all of their belongings with them, too? No human ever left any of his belongings down by a riverside, or in a low valley somewhere? No human fossils or human artifacts have ever been found in anything but the absolute most recent (generally uppermost) layers of rock strata. Not even once. Not a single arrowhead. Not a single pot. Not a single stone tool. Not a single bowl. Not even an animal bone with telltale markings on it, indicating it had been carved up by manmade tools. On the other hand, we find all of these things and more when we come to rock layers that are geologically dated to be within the last several hundred thousand years.



An even bigger problem for the creationist explanation for the orderly progression of fossils becomes apparent when you think about plants. You see, plants also follow an orderly progression in the fossil record. For example, modern flowering plants (including some trees) don’t appear in the fossil record until relatively recently, during the age of the dinosaurs. The absolute oldest flowering plants appear in the fossil record at around 120 million years ago. Most species of flowering plants are found in rock layers much higher (and so more recent) than that. Yet, there are many layers of rock strata beneath these layers that contain fossils of land plants and land animals, and we don’t find ANY flowering plant fossils in these layers. Why are fern fossils found in layers of rock strata much lower than flowering plants? Did the flowering plants all sprout legs and run uphill to escape the rising Flood waters?



What about eggs? Many fossils of dinosaur eggs have been found. Again, we find some land plant fossils and land animal fossils in layers of rock strata far beneath the layers where dinosaur eggs are found. When dinosaurs laid their eggs in low valleys or down by a riverside, did the eggs roll/float uphill, only to rearrange themselves back into nice, neat nests when they reached their final resting place? Apparently, the creationists would have us believe that dinosaurs never built nests anywhere near sea level. Apparently, though, those dinosaurs had some pretty strict rules about how far above sea level they should build their nests, because we sure don’t find any dinosaur eggs in rock layers dated to be more recent than 65 million years ago. Weren’t there any dinosaurs that died or left nests on hillsides or on other high ground near the modern mammals? How could anyone possibly believe that a worldwide flood covered all of the land on the earth, and still managed to leave many dinosaur nests intact?



Didn’t any of the flying reptiles (pterosaurs) manage to make it to the top of a hill? None of the dinosaurs (not even the small ones) made it to high ground where most of the larger, modern mammals were? None of the larger, or more modern mammals got caught down in a low valley with the dinosaurs and were fossilized in the same layer as dinosaurs? Not a single such example has ever been found. NEVER. Not once. The only mammal fossils that are found in the same layers with the dinosaur fossils are small, primitive ones that show many reptilian anatomical features. In other words, the only mammal fossils that are found down with the dinosaurs are the ones that look like intermediates between reptiles and modern mammals. Imagine that.



How is it that the elephants and mammoths managed to make it to higher ground than some species of flying birds? (The earliest species of flying birds are found MUCH lower than any mammoths or elephants.) Note that creationists can’t squirm out of this one with hydrodynamic sorting, either. Would they have us believe that elephant bones sink more slowly than the hollow bones of a bird?



Let’s pause for a moment and reflect on this image. The flood waters are rising. Animals and flowering plants are running uphill to escape the rising water. Humans are running around like mad making sure they take their bowls, cups, arrowheads, and all of their other belongings with them when they climb the mountains. We come to a steep hillside. The dinosaurs are too dumb to figure out that you can actually run uphill, so they stop running and drown. Any dinosaurs that happened to be on high ground run downhill to get a drink. The elephants and mammoths, with their greater intelligence, keep running on up the hill. Many species of flying birds, however, just can’t climb mountains as fast as Dumbo the Flying Elephant, so they get left behind and drown.



Pure. Comedy. Gold.



I could probably fill a book with such inconsistencies between the predictions of the creationists’ explanation and the existing fossil record. The ones above are just a few that popped into my head quickly.



The fact is that the organization of fossils in the different layers of rock strata is not at all what one would expect if they had formed in a worldwide Flood. Instead, the fossil record looks exactly like what we would expect to see if evolution is true. If you look at the aftermath of any modern flood, you see utter chaos. Creationists would have us believe that the worst disaster in the history of the world left no such indications of chaos at all, but instead left an orderly fossil record and nice, neat, orderly layers of rock strata.



Another problem with the idea that fossils were formed during Noah’s Flood is this: in many fossils, we find extremely delicate structures that are well preserved. (Fossilized eggs are one example – there are thousands of other examples.) How could such delicate structures be well preserved by a worldwide disaster that dwarfs any natural disaster known in modern times? Isn’t it much more reasonable to say that fossilization is a slow, gradual process?



TRANSITIONAL FOSSILS

Another line of evidence that strongly supports evolution is the fact that many fossils have been found that look like perfect transitional fossils between major taxonomic groups. For example, look at the following sequence between apes and modern humans:

Ape-human transitional fossils (You may have to scroll down slightly to see the figure.)



The fossils are arranged in chronological order (according to geological dating methods). The skull on the upper left is a modern chimpanzee skull. It’s there only for comparison purposes, to show how apelike the earliest fossils in the ape-human sequence are. As you move along the sequence (left to right for each row), notice how similar each one is to the preceding one. When you get to the modern human skull, jump back and compare that one to fossil “B”, to see how far you’ve come. In particular, notice how different the size of the brain case is, and how flat the modern human face is compared to the creature you see in “B”. Notice how gradually this change occurred. Finally, take note of the ages of these fossils beneath the photos. Notice how these fossil ages place each fossil skull right in there where it belongs in the sequence. Now, it probably isn't the case that every species in that figure is a direct human ancestor. In particular, neanderthals probably were not our direct ancestors. Nonetheless, when you look at that sequence, it's pretty clear that there are some gradual, smooth trends. Not a single fossil has ever been found that is significantly out of place in this sequence. (If the inclusion of neanderthals in this figure still bothers you, you can replace them with these recently found fossils. The more recent fossils would make the figure look better anyway.)



Creationists usually respond to examples like the one above in two ways. First, they like to argue that these transitional fossils are “just apes” or are “just humans”. This misses the point entirely, because the evidence for evolution here comes from the fact that even a brief look at the anatomical features of these fossils shows a clear progression from apelike ancestors to modern humans. In particular, notice how the size of the braincase grows with time. Notice also that the face gradually becomes flatter over time.



What would you expect from a transitional fossil? Well, one thing you would certainly predict is that transitional fossils should be hard to classify. That’s because a transitional fossil should show a mixture of anatomical features between two taxonomic groups (apes and humans, in this case). Since the fossil is neither completely “A”, nor completely “B”, we should find disagreement about which modern taxonomic group the fossil belongs to. Well, let’s look at how the creationists have classified these fossils. Maybe the creationists should get together and have a huddle before they write their articles. If even the creationists can’t decide whether these fossils are “just apes” or are “just humans”, what does that say about the fossils themselves? To me, it says that they are somewhere in between.



The other common creationist claim is to point out that paleoanthropologists have not reached a consensus regarding which hominid species are direct ancestors and which are not. This much is true. However, this is not a problem for evolution at all. As I’ve discussed above, the evidence for evolution comes from the observation that there are obvious, clear trends that can be seen in the hominid species found in the fossil record. For example, consider the relationship between brain size and fossil age. (Scroll down to the figure at the bottom of the page.) Even a brief look at this figure shows that there is something interesting going on here. Brain size gradually increases over time. It makes no difference how many of the species in this figure were our direct ancestors and how many were “cousins”. If an increase in brain size is a consistent overall trend that occurred in the hominid lineage, then it should be true of both direct ancestors and “cousins.” For example, neither neanderthals nor Australopithecus robustus are considered to be our direct ancestors. So what? Evolution clearly predicts that both neanderthals and robustus must have been closely related to hominids that were our direct ancestors. This means that neanderthals and robustus must have been anatomically very similar to the hominds living at the same time that were our ancestors. We expect neanderthals to have a much larger brain than robustus did, because neanderthals evolved from more recent homo sapiens ancestors. As the brain size-fossil age figure shows, these predictions are confirmed. The gradual increase in brain size is a general trend that applies consistently, both to direct ancestors and to evolutionary dead-ends that were closely related to our direct ancestors. The same applies to other anatomical characteristics, such as the flattening of the face. There is only one reasonable explanation for such clear and consistent trends – we evolved from apes.



Creationists like to claim that there are no transitional fossils. This is, perhaps, the single most common creationist argument of all. As we’ve seen in this section, it is an absolute lie. In fact, transitional fossils are abundant.



IMPOSSIBLE CREATURES



Another line of evidence supporting evolution is the fact that the pattern of anatomical similarities between the various species is consistent with evolution, when there are countless hypothetical organisms that would be grossly inconsistent with evolution. Many new species are discovered every year. Year after year, decade after decade, we fail to find even ONE such violation. Creationists complain that anatomical similarities do not provide evidence for common ancestry. However, this argument misses the point. The evidence for evolution comes not from a simple observation that some species look like other species. The anatomical similarities between species provide evidence for evolution because they follow a specific, highly predictable pattern.



One important point is that the various species are more similar to each other than they need to be. Creationists explain similarities by claiming that organisms share similar anatomical features only because they have similar needs. For example, they argue that the legs of various animal species look similar because there are certain design constraints that apply to any animal that runs or walks. For example, a leg must have good structural support, because it must be able to absorb the regular pounding that occurs when the animal runs, and it must be able to do this for the entire lifespan of the animal. Therefore, since the legs of different species have the same design constraints, God created them (independently) with similar anatomical features. Sounds like a pretty reasonable argument, doesn’t it?



Well, not when you think about it a bit more. For one thing, this argument fails to take into consideration cases where two species share remarkably similar structures that perform different functions. Bird wings provide a few good examples of this. As everyone knows, the wings of most birds are nicely suited for flight. Right away, it’s easy to think of problems for the creationist explanation. What about flightless birds? Why do ostriches and penguins (for example) have wings that share many anatomical similarities to the wings of flying birds? (For example, the flightless birds have fused finger bones, just as modern flying birds do.)



There are countless other examples. Let’s stick with bird wings for a bit. According to evolution, bird wings were modified from the forelimbs of ground based reptiles. Since bird wings and reptile legs perform very different functions, why would they share so many similarities? If you look at the bones of a bird’s wing, you find the same ones that are found in a reptile’s leg, or a mammal’s leg, or a human arm. This is because the basic design of a leg is a very old one that has been modified in different directions for reptiles, birds, mammals, and humans. In the case of bird wings, some of those bones have been heavily modified. For example, the finger bones have all been modified, and some have even been fused with each other. Modern birds have fused digits. In spite of these modifications, the telltale similarities with legs are still found. Right away, you can see that evolution makes a clear prediction about what we should find in the fossil record – fossilized birds with the finger bones still separate, indicating an earlier stage in the transformation from “leg” or “arm” to “wing”. As the photo shown on this site shows, that’s exactly what we find. Archaeopteryx is a fossil bird found in rocks approximately 120 million years old. It displays a fascinating mixture of birdlike and reptilian anatomical features. In this photo, compare the obviously separate fingers of archaeopteryx to the fused fingers shown in the drawing of the bones of modern bird wings (see the previous link). (Just as a quick aside, recently a number of more primitive reptile-bird intermediates have been found, including a number of fossils of birdlike, feathered dinosaurs.)



For an even better example of similar structures performing different functions, let’s look at the bones of bat wings. Note that the wings of the bat have the same bones that are found in a human arm, or a dog’s leg, or a bird’s wing. In this case, the finger bones have been modified to provide structural support for the wings. In a dog, these bones are part of the toes, and they help to improve the animal’s agility while walking or running. In a human, these bones are part of the fingers, which are used for yet a third (completely different) purpose. Evolution provides a good explanation for such similarities: dog legs, bird wings, bat wings, and human arms were all modified from the front legs of distant ancestors that were reptiles. We see such homologies all the time. The anatomical similarities exist because evolution takes an anatomical feature and modifies it (in different directions for different lineages) over time to serve a new function. If you don’t believe in evolution, then you are left fumbling for an explanation for why God keeps using similar designs for totally different functions.



At this point, some creationists claim that God worked from a kind of “template” when creating species. The argument is that He used (for example) a “forelimb” template, and only made the modifications that were necessary for each particular species. But, wait just a moment – we humans use templates to compensate for our own limitations. Using a template allows us to consistently stick to a set of design specifications, without allowing the kind of small inaccuracies that would occur if we didn’t use the template. What does an all powerful, infallible God need with a template? Religious people believe that God figured out a way to store all of the necessary information to build a human body in a space too small to be seen without a microscope. Creationists would have you believe that this same God needed to use a template to avoid screwing up the macroscopic design of a bird’s wing? Even dumb human scientists and engineers can build a good set of wings (airplanes). I highly doubt that the Almighty Creator of the Universe needs to work from a template to construct a set of wings.



In the case of birds and bats, the bone structure is very similar, as we have discussed. This is because bird wings and bat wings are believed to have evolved independently from reptile legs. Here, we see that evolution tells us exactly what similarities to expect from both modern specimens and fossils. If bird and bat wings evolved independently from reptile legs, then we should find that they both are similar to reptile legs and to each other in many ways. As we’ve discussed, there is no biological reason why such similarities MUST exist, unless you believe in evolution. On the other hand, features that are specifically related to flight should show few similarities between bats and birds. In other words, if flight evolved independently in bats and birds, then we wouldn’t expect evolution to solve the problems related to flight in exactly the same way.



This brings us to another important point. There are many possible designs that could get the same job done. With the above discussion in mind, let’s consider the wings of birds and bats a bit further, and compare them to the wings of flies. They all share a certain superficial similarity. All serve the same biological purpose. Clearly, though, the wings of these different species are very different, despite the fact that they all serve the same biological function. This is an example of what biologists call analogous structures. As shown above, the finger bones of modern birds have become fused together. Most of the surface area of the wings is, of course, made up of the flight feathers. In contrast, the bat has separate fingers. The wings themselves are a thin membrane that is essentially two layers of skin, with nerve endings, blood vessels, etc. The wings of flies contain no bones at all. Insect wings are extensions of the cuticle and are, therefore, not true appendages like the wings of birds and bats are. Insects, birds, and bats all have wings adapted for flight. Yet, since they all evolved wings independently, from flightless ancestors, the wings are completely different. Same function – totally different anatomy. What’s the point? The point is that it isn’t enough for the creationist to simply dismiss similarities between species on the grounds that different species need closely similar anatomical structures to perform similar functions. There are many different potential designs that can get the same job done.



Again, evolution tells us when to expect anatomical similarities, and when to expect differences. Stated generally, if anatomical feature “X” was present in the common ancestors of species “A” and species “B”, then we expect X to be homologous (i.e. anatomically similar). On the other hand, if X was not present in the ancestors of A and B, then X should show many anatomical differences, because X must have evolved independently in A and B. (In other words, X should be analogous.) Applied to the current examples, we see that the bones of the forelimbs (whether they are arms, legs, or wings) were present in the common ancestors of all of the species we’ve discussed. As predicted, the same bones are found in bats, birds, humans, mice, reptiles, dogs, etc, etc, etc. On the other hand, the various adaptations that specifically allow for flight were not present in the reptiles that birds and mammals evolved from. Since this means that wings must have evolved independently in birds and bats, we expect to see different solutions to the problems posed by the need for flight. As predicted, we do.



Here, a smart creationist might accuse me of circular reasoning. After all, if I am using evolutionary relationships to predict when creatures should share anatomical similarities, how can I then turn around and infer common ancestry on the basis of those same predictions? However, the circularity is only apparent. The important point is this: if the various species of life on earth had been created independently, then we should find many gross inconsistencies when this analysis is performed on different anatomical features in different species.



For example, why couldn’t bats have had the kind of long flight feathers that birds have, instead of membranous wings? The wings of birds show us very clearly that such a design works just fine. If a bat were ever found with feathers, it would be very difficult to explain in terms of evolution. In every other respect, our feathered bat would be a mammal – it would have mammalian teeth, the females would bear live young instead of laying eggs, mothers would nurse their young, males would have a penis, etc, etc, etc. So, where could we place this animal on our phylogenetic trees? If we say that it evolved from mammals, then we would have no good explanation for where its feathers came from. If we say that it evolved from birds, we would have no plausible explanation for where its mammalian features came from. We could try to claim that both birds and mammals evolved from very ancient feathered reptiles, but that would leave us wondering why no other mammal species has ever been shown to have feathers. It’s easy to see that it would only take a small number of such examples to completely destroy evolution. Our hypothetical feathered bat is a perfectly reasonable organism that doesn’t even begin to fit anywhere on our phylogenetic trees, and there is no good way to modify those trees to accommodate it.



What all of this is leading up to is the observation that there is an orderly, highly predictable pattern to the anatomical similarities found between species. When we look at life on earth, we find that organisms can be classified into a hierarchical pattern of groups, based on anatomical considerations such as the ones we’ve been discussing. These various groups form what is referred to as a phylogenetic tree – a gigantic family tree, encompassing all known life forms that have ever existed on earth. Creationists often argue that these phylogenetic trees are completely subjective, but that’s clearly not true. Consider the following creatures, and classify them into two groups: penguin, chimpanzee, human, eagle, dog, ostrich, owl, sparrow, cat, lion, wolf. Would anyone seriously argue with the idea that “birds” and “mammals” are separate groups? There are certainly other classification schemes that one could use. For example, one could group those organisms according to adult average weight – above 100 lbs or below 100 lbs, maybe. But, if you did that, people would think it a bit odd. Why? Because most people realize that there are a large number of anatomical features that “birds” have in common with each other, and that are distinct from “mammalian” features. Now, we can take it a step farther. Consider the mammals on that list: chimp, dog, human, cat, wolf, lion. If asked to classify those creatures into subgroups, most people would come up with: Primates – human, chimp. Canines dog, wolf. Felines – cat, lion.



In other words, life on earth can be objectively classified into a nested pattern -- groups within groups. There are very few things in the world that are like that. The best creationist reply I could think of would be books in a library. You could classify them into “fiction” and “nonfiction”. Then, you could classify the “nonfiction” books into a few groups – things like “science”, and “economics”. But, if you did that, you would quickly run into a hopeless number of inconsistencies and conflicts. First of all, you’d find different classification schemes used by different people. For you, the first level of classification beyond “nonfiction” might be things like science, philosophy, religion, economics, etc. Someone else might have an additional level of classification – textbooks vs. books for the popular press, for example. Beyond that, you’d run into more serious problems. You’d quickly start to find a lot of books that couldn’t be conveniently classified. What about a book like “Consciousness Explained”, by Daniel Dennett? It has clear elements of both science and philosophy. Dennett is a philosopher, so you might be tempted to classify it as philosophy. Yet, there is a tremendous amount of neuroscience data discussed in the book. What about a book about biology, written for children under 10? Should it be classified as “science” or a “children’s book”? Most bookstores would put such a book with the other children’s books, but that’s solely a matter of opinion. The book itself is a great example of a science book. It’s also a great example of a children’s book. At every single level of classification, from the highest to the lowest, you would find large numbers of books that just don’t quite fit. There are even books that are a mixture of fiction and nonfiction (a dramatization based on real life events, for example).



The situation is very different in biology. Suppose an evolutionarily “disallowed” animal were discovered – something like our hypothetical feathered bat for example. If I am right when I say that evolution makes testable, falsifiable predictions about what kinds of organisms are “allowed” and which are “disallowed”, then the discovery of a clearly disallowed creature would be powerful evidence against evolution, and creationists would surely waste no time writing articles about it. No such “disallowed” creatures have ever been discovered, but that hasn’t stopped creationists from trying to “invent” one.



Enter the platypus.



The platypus is a monotreme, related to the spiny anteater. Both are from Australia. The platypus is a weird mammal, to be sure. To the untrained eye, it looks like a bizarre combination between mammal, bird, reptile, and possibly more – like something straight out of “Impossible Creatures”. Not surprisingly, every single creationist website I checked has articles on the platypus. Most have multiple articles on it.



Ken Ham, of the Institute for Creation Research writes:

"But what about the most perplexing Australian animal of all, the Ornithorhynchus anatinus, or platypus? This is a real evolutionary enigma. This mammal has a duck-like bill, a beaver-like tail; webbed feet like an otter, hair like a bear, and claws like a reptile. It lays eggs like a turtle and feeds its young on milk like a mammal. It is able to detect electrical impulses, and builds a burrow, like a rabbit, for a lair. What a mixed-up animal! Evolutionists have a real problem with this little animal. It did not evolve from anything, and it is not evolving into anything, but it is a mixture of all sorts of things. I often wonder if God made the platypus especially to confuse those who believe in evolution."



I think that God is smart enough that, if He wanted to confuse evolutionists, He could have done a better job than this. There is no reason for evolutionists to be confused by the platypus at all. First of all, the “ducklike” bill that is such a favorite of creationists is only similar to a duck’s bill to the untrained eye. Anatomically, a duck’s bill and a platypus’ bill are totally different structures that have very little in common (beyond the basic shape). Here is a comparison of features of platypus and duck bills:



Platypus bill:

1. Covered by soft skin.

2. Entire surface is covered by sensitive nerve endings, including some that can sense minute electrical impulses generated by small organisms that it preys upon.

3. Soft and (to some extent) flexible.

4. Basic structure is bone (basically, just an extended upper and lower jaw).



Duck bill:

1. Not covered by any skin.

2. Contains fewer nerve endings and no electrical sensors.

3. Rigid and immobile.

4. Basic structure is made of keratin (the same protein that forms our fingernails and reptile scales).



In short, the platypus’ “bill” is really just an elongated mammalian jaw covered by skin. By now, the reader should recognize the platypus’ bill and the duck bill as good examples of analogous structures. For further reading and some good photos check this site. In particular, check the section on “eyes, ears and nose”, and look at the photo of the open platypus bill. That’s no duck bill, no matter how badly the creationists may wish it was.



The other “anomalous” features described by Ham and the other creationists are either similarly misleading anatomical descriptions, or they are unsurprising features, given the fact that mammals evolved from reptiles. (For example, as the above link discusses, the platypus’ tail is not really that similar to the beaver’s tail at all). Finding legitimate (homologous), complex “bird-specific” features on a mammal would be a tough one to explain for evolutionists, because the fossil record (and comparisons of DNA) tell us that mammals evolved from reptiles, not birds. On close examination, the platypus has no legitimate bird-specific features at all. On the other hand, since mammals evolved from reptiles, it isn’t at all surprising to find a mammal that shares some reptilian features. And, consistent with evolution, the reptilian features are legitimate similarities:



1. The female platypus lays eggs like a reptile.

2. The skeleton of the platypus has a number of features that are found only in monotremes and the group of extinct mammal-like reptiles that mammals are thought to have evolved from.

3. Common rectal and urogenital opening.

4. Genetic similarities.



Far from being evidence against evolution, the platypus provides evidence for evolution because of the numerous characteristics it shares with the reptiles that mammals evolved from. It’s a good example of exactly what I was talking about when I compared homologous and analogous structures in the discussion above. Evolution makes testable, falsifiable predictions about the patterns of anatomical similarities that should be possible. The creationists evidently agree with me on that point – otherwise, they wouldn’t be so much in love with the platypus, and creationists like Ken Ham wouldn’t be writing things like the quote above.



New species are discovered by biologists all the time – thousands of them have been discovered since Darwin published The Origin of Species. And every one of those new species is another test of the predictions of evolution. Evolution has survived every single one of those thousands of tests – not a single species has ever been found that doesn’t fit somewhere within the great family tree of life.



CREATIONISTS RUN AWAY WITH THEIR TAILS BETWEEN THEIR LEGS



As time goes on, and evolution occurs, sometimes it is advantageous for a species to lose an existing anatomical feature. As the environmental conditions change, sometimes an anatomical feature that was once useful becomes useless, or even a liability. In these cases, a mutation that results in the loss of the unnecessary body part(s) may be favored by natural selection. The eyes of the blind cave fish (see the mutation section) is one example. The loss of the primate tail in our ancestors is another example. When this happens, most or all of the genetic information necessary for the development of the “lost” body part is still present. On rare occasions, a mutation or an environmental condition can “reactivate” the development of the lost body part. Let’s talk briefly about a startling example: the rare human born with a tail.



As human embryos develop, the tail begins to grow as it does with mammal species that have tails. In humans, downregulation of the expression (the making of a protein from the gene) of a gene called WNT-3a induces apoptosis (programmed cell death) that eliminates the tail. Very rarely, a mutation or an environmental condition maintains expression of this gene, and the tail continues to grow. If humans did not evolve from ancestors that had tails, then why do we still have the genetic information necessary to grow tails? Note that all humans have the genes necessary for tail development. It’s just that the tail normally is eliminated during embryonic development. This makes perfect sense if you believe in evolution. If you don’t, it’s a bit hard to explain.



At this point, creationists usually claim that the tail is not a true tail at all. They claim that these tails do not have bones like a true tail would. Apparently, they have never seen the X-ray shown here. Scroll down a bit, and look at figure 2.2.2. Those sure look like bones to me.



Furthermore, the only atavisms that have ever been observed are those that make evolutionary sense. For example, since humans evolved from ancestors with tails, a human born with a tail is evolutionarily “allowed”. On the other hand, a mammal born with feathers is not “allowed”, because bird feathers did not arise until long after the split between the two reptile groups that would eventually evolve into birds and mammals. A large number of atavisms have been discovered in many species. Just as evolution predicts, ALL of them involve the reappearance of anatomical features that were present in species that are believed to be ancestral, according to our phylogenetic trees. In other words, not a single atavism has ever been found that doesn’t fit within the great family tree of life that scientists have pieced together from the fossil record and comparisons of DNA.



GENETIC SIMILARITY BETWEEN SPECIES



If the different species on earth today share common ancestors, then we should expect them to be genetically similar also. The more recent the common ancestor, the more similar they should be genetically. One example of this is the fact that humans and chimpanzees are almost identical genetically (the percentages I’ve seen range from 95% identical to 99%). Now, obviously, humans and chimps look very similar in many ways, so it isn’t surprising that our DNA is similar. But, the fact is that human and chimp DNA is a lot more similar than it needs to be. I say this for several reasons. For one thing, remember from section 1 that a given amino acid can be coded for by any of several different codons. Since genes are generally thousands of base pairs long, this means that there are a vast number of different nucleotide sequences that result in exactly the same protein(s). In other words, for every gene, there are a huge number of alternative sequences that would be functionally 100% equivalent. For example, when we look at the gene for cytochrome C, we find that there are 10^46 different possible nucleotide sequences that code for exactly the same protein (Theobald, 2003). The human and chimp versions of this gene differ by only one nucleotide. The point is that there is no need for humans and chimps to be as similar as they are, unl

[RunningMn9]

The original poster was Gebeker. I don't know whether or not he's been here yet, but I can send out the bat signal.

Oh - and your post seems to be cut off. I'm sure Geb has the original though, I will make him post it in it's entirety.

[Gizah]

This piece of GG history MUST be preserved.

[Vegetable Man]

I think I have it saved in a word doc, too. I'll check if it matches up, still one of the best thread titles in GG history.