Evolution is a tricky and controversial subject. To avoid semantic misunderstanding, lets consider some definitions. The word evolution, could technically speaking refer to practically anything, since so many things can evolve one way or the other. However when most people use the word evolution without clarifying which evolution they are referring to, they usually mean "the evolution of the different species". I can understand why people would simply say "evolution" for practical reasons, but that is somewhat confusing. Because of this, many people think that the the term "evolution of the different species" refers to exactly the same as "biological evolution". I would disagree and say that although the evolution of the different species is indeed a part of biological evolution, the term biological evolution entails a lot more than just that.
Like I said, all to often proponents make it look as if anyone who disagrees with any part of biological evolution; is someone who disagrees with science itself. An often used argument is that evolution is just as much of a "theory" as gravity is. But how much weight does that argument carry? Well to avoid sweeping generalizations, let's consider the current status of these four parts:
|Abiogenesis|| Hypothesis which is incomplete, not testable, not falsifiable and not provable.|
|Micro evolution|| Theory; well established, testable, falsifiable and provable.|
|Macro evolution||Theory; still some lose ends but testable, falsifiable and provable.|
|Common descent||Speculation; completely half baked, not testable, not falsifiable and not provable.|
People who feel I have made an error here and think that Abiogenesis and common descent are either testable, falsifiable or proven,.. Feel free to present your case on my forums.
So my personal beliefs are that, several species were created metaphysically, and that those ones after that they were created all evolved trough physical laws into an even larger variety of creatures. I trust the scientific accuracy of the theory of micro and macro evolution, but I argue that they simply don't cut it to fill in common descent. As for abiogenesis, there are many scientific objections why that is unlikely as well.
Now getting back to the comparison with denial of gravity, if it is directed to someone who denies the possibility of micro and macro evolution, then I agree completely. To deny them is in many ways similar to denying the theory of gravity. If however someone denies Abiogenesis and common descent -like I do- then the comparison is inapt. These two are not scientific theories, denying them does not go in against science. I will discuss in detail how many of the proposed falsifiability, testableness and proofs for each of those are flawed. For now I'll just respond to the reply I often get from those who feel forced to agree that these theories aren't scientific indeed. the reply is, that I'm simply compromising the parts that are proven into my views, and blindly deny those that are not proven yet. A witty reply, but another way to look at it is that the parts of biological evolution that could be considered as somewhat incompatible with religious doctrine are "coincidently" the same that are not proven! Both arguments however are emotive. From a rational perspective both parties would have to agree that the validness of one theory has no bearing on the validity of another, not even if they are in the same field or have overlapping parts. Each theory should be judged only on its own merits. Despite that all four theories are somehow related, proving that two of them are right, doesn't prove the other two right as well. Any scientists with respect for the concept and principles of a scientific methodology should acknowledge that.
Well actually since there are a lot of gaps here -as stated before- abiogenesis is closer to hypothesis rather than a theory. Some scientists speculate that it happened, but they failed to explain in detail exactly how it happened. Since, it's strictly speculation at this point, no proof, no falsifiability and no testability; in all common sense, we shouldn't even label this as science. The confusion though, is that this hypothesis is backed up with some scientific speculation, which makes the hypothesis appear scientific in nature. But that however doesn't change the lack of falsifiability, testability and proofs. That being said, lets look at some of the challenges of this theory.
In 1953 the Miller-Urey experiment was conducted that attempted to mimic the conditions on earth during the time life originated. They mixed water and hydrogen as well as methane and ammonia. Then they used electrodes to emit electrical charges into the mixture. After several days of continuously charging the mixture with sparks, they managed to get about 2% of amino acids. However, much larger percentage of substances that are harmful to life also were created trough the process. Next to that the experiment didn't account by far for all types of amino acids required to make the needed proteins. Furthermore the experiment also failed to explain how these amino acids would then go on to form the required proteins. The experiment also showed some of the building blocks for nuclide acids, but again does not account for how they could have formed DNA/RNA. Furthermore, there were both left handed as well as right handed isomers in a 50% to 50% ratio, whereas only one type is used in our DNA.
Now, often people reply that this experiment only lasted a couple of days or a week, whereas the earth existed millions of years for this process to take place. But how does this change anything? The experiment was a controlled structured environment, whereas earth was an open unstructured chaotic environment, if anything the experiment should bring forth life a lot faster then the earth did, that is off course, if abiogenesis would be true. But let me expose the flaw in this counterargument by making a comparison. Lets say mankind cannot run 100m in 3.2 sec. We are simply unable to do so. Now if a track would run a stretch of 100m on a track of 200m or 300m or even 1000m; that would still not enable anyone to run those 100m of that track in 3.2 sec. In other words the length of the track -as long as it is longer then 100 meter- hardly affects the possibility of the performance because the additional length has no bearing on the likeliness of the performance. Likewise; the many years that the universe existed, and the many planets that were suitable for this process to occur does not influence the likeliness of such a process to be possible. If a process that should take 5 minutes cannot occur in a week, it cannot occur in a million years either. The amount of time available, as long as it is enough, doesn't make the chemically impossible into probable. Just putting ingredients together and stirring it up doesn’t suffice. That’s as ludicrous as saying that if you shake a box of Lego blocks long enough, eventually the building blocks in the box will spontaneously construct the house that is displayed on the front of the box.
But that's just the beginning. Next to the shortcomings of the experiment a lot of other criticism exists as to how representative it was. The experiment did not contain oxygen, since oxygen generally oxidises anything it comes in contact with. This oxidation is quite destructive. Some scientists reply to this that the atmosphere didn't contain oxygen at that time. Be that as it may, no oxygen means that there also was no ozone, which is formed by oxygen. Ozone blocks us from UV light from the sun. Without ozone we'd be bombarded by it. And UV-light breaks down ammonia, one of the major components of the experiment. So I guess you're catching my drift by now. Either the experiment should have contained oxygen, to account for the presence of ammonium or we have to explain the high presence of ammonium despite the lack of ozone.
Another angle to looking at it -panspermia- is even more far fetched. Rather then only suggesting lightning struck at the exact same spot for a whole week, it also suggest that a meteor carrying amino acids also hit the very same spot. Now it is true that some meteors carry amino acids and that under unique circumstances the impact could cause peptides. But these peptides are short chains of amino acids, not the long proteins necessary for life. Furthermore it's even more unlikely considering not just any meteor would fit the bill. It has to be exactly the right size. Not to small so it doesn't burn up in the atmosphere destroying the amino acids, and not to big so the impact isn't to destructive either. At the same time delivering enough energy for the chemical process to take place. Also note, that this shifts part of the problem. It's true that some meteors carry amino acids, but how did those amino acids form in the meteor in the first place? This simply avoids the problem of having to explain how these molecules were formed trough natural processes.
Theory or hypothesis?
The biggest problem of this theory is a concept recently coined as "irreducible complexity". This refers to an organism or part of an organism that is complex in the sense it has multiple components, components which by them self have no function. Because of survival of the fittest, useless components will not evolve. So the only way to account for all components trough evolution, is if all those useless components were created all at once to form a useful organism. That is why the organism is irreducibly complex; it has to have been created at once and cannot be reduced into multiple steps. Some evolutionists have tried to counter this argument by suggesting that components could have been borrowed from other organisms. However this doesn't cut the mustard. Only some of the components which need to be accounted for in organisms are shared with other organisms. Next to that, those shared components that are shared in multiple organisms are often borrowed form yet another irreducible complex organism. So in the end this still doesn't explain how a chemical molecule, which has no function when isolated, could have been selected trough the process of survival of the fittest. A much more detailed explanation of this, can be found in this movie: Intelligent Design - Unlocking the mysteries of life.
Lets pick up where we left of with abiogenesis. Say that for the sake of argument a single-celled self-nourishing and reproducing organism originated. How did it evolve into a multiple-celled organism?
Remember how we talked about most prokaryotes using a very specific enzyme to convert methane out of hydrogen and carbon dioxide in order to harvest energy. Well all prokaryotes (organisms that do have organelles with membrane-boundaries) rely on a different more complex process called the tri-carboxylic acid cycle, or a.k.a. Citric acid cycle. This cycle is a 12-step chemical process. Each step relies on a different enzyme as catalyst, and each step is vital to the chain in order for it to eventually extract raw energy out fats, carbs and proteins. Of course these components need to be broken down by the digestive system first; which is a whole different story altogether. So by what process could one very specific process of energy harvesting evolve into a completely different, complex system? Remember that this is a vital characteristic of life, so an intermediate organism, that isn't able to harvest energy is out of the question. Building a second while the first is still functioning is also very unlikely, since each step wouldn't have any benefits for the organism so it can't rely on survival of the fittest.
This irreducibly complexity does not occur only on the chemical level, but can also be found on a much larger level; with organelles and organs, and even with complete biological systems or animal classes. Although I do grant that most organs and organelles could have evolved out of a more simplified version. At some point, these simplified versions would have some degree of irreducible complexity to. A common argument discussed in this line of argument is the eye. For the eye to do what it's suppose to, it needs several components, a lens, muscles to adjust it, light receptors, nerves, and so on... Recently a reply has been formulated by evolutionists that speculates on how mollusc could have evolved from eye-less to seeing, by intermediate steps. The speculation goes that it went from pigment rich skin, light sensitive spots, light sensitive cavities, light sensitive cavities with liquid in it and finally to light observing with liquid and a lens. And some of the needed intermediate steps have been found among the mollusc. However the speculation is incomplete. For the theory to work; each change should have been possible from a single genetic mutation. So is it possible for a snail to go from light sensitive to light observing cells and at the same time evolve the necessary neural changes for the light impulses to be registered, let alone to make sense? Some might reply, that they could have adapted to the new type of impulses. But somebody who claims that doesn't really understand what adaptation means. Adaptation in biology, is a variation on survival of the fittest. It explains how a feature can be preserved after it mutated. It does not account for the origin of the new feature. So replying to me that they could have adapted is like saying there was a secondary mutation to take care of it. Which brings me back to my original statement, that the organ is irreducible complex since it would have to rely on multiple mutations at once. Similar arguments can be made for all other steps, as well as for other organs and organelles. But more importantly, not only does common descent speculate that an organ like the eye evolved naturally against all odds, it also speculates that this unlikely event occurred multiple times for multiple species! The mollusc for example, are speculated to be from a different branch as the insects; so the evolution of molluscs eyes cannot be used to account for insect eyes, which are a lot more complex by the way. The same goes for other species like mammals; who allegedly formed eyes completely independently.
And we can find irreducible complexity at yet an even larger scale when considering abilities of species. Certain abilities, like flying, breathing underwater, breathing above water, digesting, reproducing trough cell division, reproducing trough male and female, all these abilities rely on multiple organs, organelles and characteristics. That is to say that some animals, or at least some type of animals like fish, bird, mammals, reptiles,... are irreducibly complex. They requires multiple organs and features to do what they generally do. A single of those features does not have a function, and the ability requires multiple features.
Having discussed the biggest challenge to common descent, let us consider some of the common flawed arguments in its defence. The most basic argument in favour of common descent is, that since so many animals are so similar, it's most likely that they evolved from one another. But just because things look alike doesn't prove anything. However I'll discuss the flaws of this type of argument in detail in the next section, so I'll leave it with that for now.
Next to making comparisons, some try to enter the fossil record as proof for common descent. The argument goes, that fossils show up in certain layers of ground which in term are linked to certain eras in time. If you then make a timetable of which time the fossilized creatures lived in, it matches the timetable that common descent proposes. Well first of all, that's hardly any proof, all it does is proof which creatures lived at which time, it doesn't proof which evolved into which. Creationists might just as well claim that this proves at which time certain animals were created. The fossil record does not favour common descent over creation. In fact quite the opposite can be said, the fossil has many issues that reflect bad on common descent. Like the Cambrian explosion. An era where there's a sudden high concentration of entirely new species, as opposed to the slower pace of evolution in other eras. Another problem are the large number of missing links. There are so many proposed intermediate species missing, that some scientists have started suggesting that rather then evolution trough slow steps, there must have been "jumps" to. But that's of course very unlikely. A mutation that carries benefit is in itself unlikely, many mutations at once that carry some benefit is close to impossible. Other than that it needs to be noted that there's a lot of controversy regarding the accuracy of dating fossils. I wouldn't go as far as saying that it's all a hoax, like some Christian creationists claim. But lets just say it does indeed require a lot of work, and the margins of error are larger then usually admitted.
A similar argument, is that if you make a tree of heritage, based on similarities in DNA between creatures, then you have more or less a similar tree to the tree of descent that common descent proposed. But this information is actually false. First of all, only the genome of 4 animals has been decoded so far. (Humans, chimp, mouse and fly). So we're far from making a thorough comparison, more detail about comparing DNA can also be found in the next section. Basically what they compare are karyotypes, not DNA. But even then, the argument is a false. When DNA was discovered, and they started comparing karyotypes, the tree of descent they formed based on this discovery actually contradicted the earlier proposed tree of descent rather then conforming it! So in a way this didn't make the theory falsifiable, but it falsified the theory. Of course the theory wasn't really falsified. They just had a fresh start for evolution and they had to revise the whole theory. So the current tree of descent is based on this comparison of karyotype, and not confirmed by it! However this teaches us an important lesson. The alleged tree of descent cannot be used as falsification for the concept of common descent in itself! No matter how many times you would falsify the tree of descent, proponents of common descent would be able to suggest new alternative trees. So since falsifying the tree doesn't defeat the idea of common descent, that means the tree of common descent cannot be used as falsification for the theory of common descent.
Evolution of mankind is a very specific and dominant part of common descent. Although several proposed links by the three of common descent can provide interesting debates, I feel that this one is most appropriate for two reasons. The firs reason is that it is most relevant in this context of religion. The second reason being that it is the alleged link in the chain that is most studied and documented out of all the links in common descent. Thus it provides for a much more in depth analysis. Some people are under the impression that this part of common descent is as good as proven, but that is far from true. I'll attempt to discuss some of the commonly used, flawed arguments.
This is perhaps the most dominant argument. But it is a slippery slope. The argument holds that things who look alike, must undeniably have evolved from one another. That is off course uncertain. Similarity could just as well mean that they were created by the same creator rather then evolved out of the same specie. The similarity does not prove one viewpoint to be more likely than the other. So since multiple explanations are plausible for explaining these similarities, they cannot be used as evidence. It is often suggested, that although there are indeed several plausible explanations, that common descent is much more plausible due to Ockhams razor. I've already replied to that in my introduction page, where I discussed the weakness of Ockhams razor by example of the anthropic principle.
Also note that the comparisons are usually made in the wrong way. For example, many of the alleged intermediate species between ape and human, are argued to be human after all. Here are some proposed missing links:
I. The Australopithecus
The false claims from Richard Leakey and Donald C Johanson that the Australopithecus walked erected has been refuted and it seems the Australopithecus is more closely related with orang-outangs which according to evolutionists is from a different branch then the one mankind originated from. So the entire Australopithecus genus can be refuted as intermediate link.
II. The Home Genus.
II.i. Homo Habilis 2.2 to 1.6 million years ago (proposed in the 60's as first humanoid that walked erect and used tools). New discoveries in 80's showed a different picture and Bernard Wood and C. Loring Brace said that this was in fact nothing more then An Australopithecus Habilis. So it's just another extinct African ape.
II.ii. Homo Rudolfensis 1.9 to 1.6 million years ago. It refers to a single fragmented skull found in Kenya. However most scientists have accepted it again as nothing more then Australopithecus Habilis.
II.iii. Homo Erectus 2 to 0.4 million years ago. Although this skeleton is exactly the same as some humans have, evolutionists have classified it as a transcending specie, based on the small skull contents (900-1100 cc) and because of the big eyebrows (of the skull). However, there are humans alive today with that skull contents (i.e. Pygmies), and that have such eyebrows (i.e. Australian Aboriginals)! So there is no reason to assume these skeletons are a missing link, they are just humans. In fact the New Scientists of 1998 14 march even wrote an excellent article of how Homo Erectus had the technology to build and use transport ships.
II.iv. Homo Sapiens archaic 400 to 200 thousand years ago. Again there's no reason to assume they weren't human, in fact many researchers have even concluded that they are exactly the same as Australian Aboriginals. They even found skeletons of them showing that this race lived up to fairly recent times in villages in Italy and Hungary. The dramatic pictures of hairy human-like apes you found in school handbooks are just indulgence of imagination, remember we've only found skeletons.
II.v Homo Sapiens Neanderthals 200 to 30 thousand years ago. Erik Trinkus, palaeontologist of university of Mexico writes: detailed study of the skeleton of the remains of the Neanderthals with modern man show that nothing in the anatomy of the Neanderthal such as movement, manipulation, intellect and linguistic capabilities are inferior to that of modern man.So as you can see, with two Genus failing as intermediate, since each consists of many links not holding up to scrutiny, we have quite a big gap in our line of descent. Now I'm not going to claim there's some sort of crazy conspiracy going on here, and that evolutionists purposely create false intermediate species. But perhaps people are just looking so hard for these missing links that they start to see things that aren't there. Also, we need to remember species have both a genotype and a phenotype. The genotype refers to the genes a specie carries, both the dormant as well as the active. The phenotype refers to the physicals characteristics a specie has. To give an example, a person can have the genotype for both blue as for brown eyes, in other words he has both the genes that causes eyes to be blue, as the gene that causes eyes to be brown. However he will only have one phenotype, he will have brown eyes since the gene for brown eyes is dominant over the gene for blue eyes. The reason I bring this up, since evolution takes place on a genetic level, it seems crucial that we'd compare genes, rather then say comparing skulls. I have already illustrated how easy a bias can influence a researcher in comparing morphology of skulls.