Tuesday, October 9, 2007

The Fossil Record: Insurmountable Creationist Dilemma

A Genuine Problem

The fossil record reveals innumerable strange species of organisms, both plant and animal (and other), that are not alive today. It exhibits a high degree of order in the way in which these species are arranged. Based upon careful observation of nature---such as the cataloguing of both living species and those in the fossil record---scientists' best estimates are that more than 99% of all species that have ever existed on Earth are now extinct. In short, the fossil record begs for an explanation.

So far as I know, Christendom did essentially nothing to try to explain the fossil record prior to the establishment of the scientific method. Only after science came along were Christians forced to seriously consider the problem. And, as a result of scientific progress, many Christians now subscribe to a long-age Earth and even to evolution. This transition has not been without great resistance, and there are still a few on the fringe who cling to creationism (ex nihilo, in six literal days) and a young-age Earth (roughly 6-10 thousand years). I hereafter refer to them as "creationists", and it is about them that I write this blog---because they can't explain the fossil record.


Evolutionary Considerations

A ubiquitously common tactic creationists use is the setting-up of a false dichotomy: they try to poke holes in a scientific idea, and if they think they've succeeded, then they feel justified in claiming their own theory was right all along, afterall---as if there's no other explanation imaginable. They think you don't need to critically examine their theory because, "hey, it's the only remaining option." In other words, rather than presenting a positive case for the truth of their own theory, they present a negative case for an opposing theory, as if disproving it somehow proves their own (which, of course, it does not).

This is a terribly dishonest way to go about doing things. But what transforms it into something (almost) comical is how stunningly creationists display their total lack of understanding of the scientific theories they seek to disprove. They concoct hare-brained ideas to supposedly refute points that aren't even made by a theory, or they mistakenly assert (due to misunderstanding) that other scientific theories contradict the targeted theory, or they flat-out lie about things, or they latch onto ideas that allegedly contradict a theory that, upon closer inspection, actually necessarily support it! They prance about, vividly displaying their abject ignorance with all the confident pomp of a strutting peacock during mating season, but with the fidelity and intellectual content of a peanut-replete turd. (I describe a few of these idea-turds in the next section.)

For example, probably the most common claim made by creationists about why the evolutionary explanation of the fossil record fails is the so-called "missing link". (I won't even bother to get into the whole ladder- versus tree-of-life misconception.) Let's consider this for a moment. Suppose evolution is true (even if you don't think it is); everything got here through countless small changes from some common ancestor billions of years ago. Organisms continuously transition from one to another (as opposed to saltationism; large, abrupt, single-generation "transitions"). Each organism's entire ancestry plays more like a full-speed movie than a discretely-changing slideshow. What, then, should we expect to see in the fossil record?

Should we anticipate a fossilized sample of every "species" that has ever existed? Of course not! Fossilization conditions occur only very rarely, so we should expect quite a few "missing links"---much more like a slideshow than a movie. It's like filming a ballet with a movie camera containing a reel of faulty film that only records one-in-a-hundred frames to which it is exposed. When you have a friend watch it later, it will look like a slideshow, not a continuously-changing dance; she'll be forced to interpolate the differences, to infer what actually happened in the gaps. But, her "dance hypothesis" is obviously far from being disproved by these gaps. It is, in fact, in perfect accord with them.

Furthermore, even when the rare conditions for fossilization do occur, there are many organisms that simply don't fossilize, due to their size and physical composition. For example, soft-bodied organisms are notoriously rare in the fossil record because they quickly decompose, whereas the fossilization process typically takes quite some time.

Finally, even if a specific fossil really does exist, it is still very difficult for people to actually find it! So, a "missing link" is not just a failed disproof of evolution; it is actually a fulfilled prediction of the science, and of common sense! (Fortunately, some ancestral lines are better-preserved than others, so we are not forced to rely entirely upon "the slideshow". In particular, there is a very good line-up of cetacean evolution, as well as teosinte/corn and sticklebacks and several other organisms.)

Creationists also commonly cite the Cambrian explosion as being outside the capabilities of evolution to explain. However, not only is the Cambrian explosion of great interest to evolutionary scientists and the subject of much active research to improve understanding, but the overarching theory of evolution explains the emergence of new life quite adequately (especially in light of the plethora of other lines of evidence and the relatively sparse evidence surrounding the so-called Cambrian explosion). It is true that there are some unknowns surrounding the Cambrian explosion---although probably a lot fewer than many creationists think---but that's precisely why it is the subject of research. Creationists aren't out there trying to answer these questions, and they seem oblivious to the fact that the Cambrian explosion blatantly contradicts their own "six-day creation" theory. (See wikipedia for a brief overview of the Cambrian explosion.)


Creation/Flood Considerations

Now, let's do something creationists don't seem to ever do: critically examine creationist claims. I have heard several arguments set forth by them, but I can't think of any that are valid. All of them are so superficially contrived as to be laughable, often times being transparently self-problematic.

For example, when asked about the apparent age of the Earth/universe/etc., I have heard creationists seriously respond with the metaphor, "When God made a tree, he made a whole tree." In other words, "God just made the universe to appear ancient, even though it's really not!" And, so ends their "argument"; they conduct no follow-up implications or analysis or anything. I'll fill-in one obvious implication that contradicts their own beliefs immediately: if such an argument is based on truth, then God is a trickster, a liar; he purposely deceives us by planting fake fossils. Since the idea creationists are defending is a creator-God that is good and just and loving and so forth, the argument reaches a contradiction and invalidates itself. (The absurdity of this argument as a defense is made even more apparent when you recognize that it could just as readily be used to claim that all things, including you, were created one second ago. That's right: you did not just read that sentence; you just think you did. Riiiiight.)

But, there are other creationists who are at least willing to accept that things are the way they are because "some natural process(es)" made them that way. The problem is that their attempts at explaining things "naturally" within a creationist timeframe are geriatrically feeble to a Methuselah degree.

Consider the exact ordering and segregation of species in the fossil record. Evolution explains this; in fact, it depends upon it. (Different types of organisms found only in distinctly different layers simply did not co-exist. Various forms of dating the layers concur.) When asked what might disprove evolution, J. B. S. Haldane famously and confidently retorted, "Fossil rabbits in the pre-Cambrian." But, there are none to be found---because rabbits did not exist then. So, what might a creationist's attempt be at explaining fossil segregation and ordering, or even the mere existence (in any form) of the fossil record itself?

Noah's Flood. (Nevermind that there isn't the slightest shred of evidence, geological or otherwise, for a world-wide flood having ever occurred, much less in the past few thousand years.) Creationists believe the fossil record was created during this great deluge, but the problem is that it can't really explain anything at all about the fossil record: it would jumble-up everything, not create nicely ordered, neatly separated layers; and, it doesn't explain the divergent ages of the different layers either.

Some creationists suggest that big/strong/fast/smart organisms tended to retreat from the rising waters, thereby dying on higher ground than other smaller/weaker/slower/stupider organisms. But, the holes in this idea leak worse than a sieve. First, we know a thing or two about floods. They devastate areas, ripping up trees and moving cars and eroding gorges. They don't leave things where they drown them; they move them around. So, the organismal layer-ordering shouldn't tightly depend upon the order in which the waters overtook those organisms. (There should be rabbits "everywhere".) But, even if we suppose the organisms do somehow remain "glued to an unchanging Earth-surface" (if the surface moves, the organisms move), we still have problems because the geometric distribution of the fossil record doesn't match. Specifically, fossils occur in layers of "stacked planes" (in 3D), not in "layers" of contour lines (in 2D). In other words, if the fossil layers were simultaneously laid-down according to this crackpot theory, then they should exist only as a "thin film" that follows the contours of the landscape; no fossils can exist above the land, or inside (initially); they must be placed on the surface, and all at once. This means that mostly-horizontal layers can't be stacked-upon (since all layers are laid-down at once), and mostly-vertical layers can't have both length and width (because to do so, they would have to extend inside the unmoving hillside). To clarify, consider a hypothetical "sabertooth contour line", representing the altitude at which sabertooths are overtaken, drowned, and fossilized. The shape of this contour line would be a "ring around a hill"; you would find sabertooth fossils along the surface of the hill at that altitude, but none inside the hill; it would not be a stacked planar layer (as actually exist). Do I even need to mention the basic stupidity in claiming that fossils around the globe are laid-down in the same basic order simply because the respective species have such perfectly consistent and precise physical "retreat capabilities" and the water rose at exactly the right speed everywhere? And, do I even need to mention the immobile organisms, such as plants, that are also neatly ordered and segregated? And the aquatic species? And insects? And microbes? etc. (This "run away" theory also does not explain the different types of sediments found in different layers.)

The creationist "explanation" of the fossil record is already in tatters. But, what about the layer dating? How do creationists try to explain away how radiometric dating (to choose one type) yields such widely divergent ages for the various fossil layers? The answer, again, is Noah's Flood. The claim is that carbon (for example) is leached out of the corpses of organisms in an aquatic environment, thereby inducing age measurements to be artificially large. Alas, this idea, too, is birthed brain dead, as will soon be seen.

The basic idea behind radiometric dating is this: different chemical elements exist in multiple forms called isotopes; some of these isotopes, called radioisotopes, are radioactive and decay into other chemicals at measurable rates; if you can reasonably estimate the starting quantity of radioisotope, you can compute the age of something based upon the remaining quantity of radioisotope. For example, carbon exists naturally on Earth as carbon-12 (about 99%; 6 protons, 6 neutrons), carbon-13 (about 1%; 6 protons, 7 neutrons), and carbon-14 (trace amounts; 6 protons, 8 neutrons). Carbon-14 is a radioisotope; through beta decay, it turns into nitrogen-14. It has a half-life of 5730±40 years. This means that every 5730 years, the amount of remaining carbon-14 in a sample has been reduced to half of what it was at the start of the 5730 years. If you start with 1 gram: you will have 1/2 gram at 5730 years, 1/4 gram at 11460 years, 1/8 gram at 17190 years, 1/16 gram at 22920 years, etc. Clearly, this decay behavior follows an exponential curve.

At first glance, this carbon-leaching idea may seem clever. But, when you look at the actual data and follow-up on the implications of the suggestion, it rapidly becomes clear that it fails miserably to explain anything real. First, let us note that in order to induce any sort of age difference across layers, the layers must be laid-down very rapidly (since the Flood is reputed to have lasted a mere forty days and nights) so that they cannot each be equally affected by the leaching---otherwise, it induces no cross-layer difference in age measurement. (Upper layers must "shield" lower layers from leaching, reducing the rate at which they lose carbon-14.) Second, the leaching itself must be quite "vigorous" in order to achieve in only 40 days the enormous age discrepancies claimed by creationists (4-6 thousand years versus, say, a billion-plus years; so, roughly a million times the age). (As a side note, I suppose I should mention that I'm well-aware of the fact that radiocarbon dating is not the type of radiometric dating used for millions-of-years age-dating, but rather only for a few thousand years. I focus on it only because creationists seem unaware of this fact, and because my deconstruction of their argument is relevant for all radiometric dating with respect to "flood leaching".)

Given these necessities, and that all the materials started with essentially equal quantities of carbon-14 (since they were laid-down simultaneously), one would expect the "final" distribution of carbon-14 concentrations across all the layers to be (at least nearly) continuous; age measurements should roughly match-up at layer boundaries, gradually changing not just inter-layer, but also intra-layer. This is not what the fossil record shows. Sometimes adjacent layers have greatly different ages, and sometimes they do not; and I know of no one who has ever recorded a gradually changing age inside a given layer. Furthermore, not only would we expect the distribution of carbon-14 to be roughly continuous, but we should also be able to predict that its distribution follows some sort of "decay curve" (rather than a linear distribution, for example). This can be modeled using differential equations, but without getting into all the nitty-gritty math, it's readily understood intuitively with the metaphor of heat: the greater the difference in temperature between a hot object and its surroundings, the faster it will transfer heat to those surroundings; as the difference diminishes, so also does the rate at which heat is transferred. (The exact temperature curve of a cooling object is dependent upon such things as thermal conductivity; but, the overall exponential "decay shape" of the curve remains true whatever its precise curvature characteristics may be.) The idea of carbon-leaching suggests that carbon-14 concentration is analogous to temperature: the greater the difference between an object's carbon-14 concentration and that of its surroundings, the faster it will transfer carbon-14 to those surroundings. So, as we descend through the layers, we should expect a "decay curve" to fairly neatly fit our measured carbon-14 concentrations; the top layer concentration should be the most changed (due to the adjacent leaching water), the bottom layer should be the least changed, and the intermediate layers should have intermediate values that roughly fall along a decay curve connecting the two extremes. Again, this is not the case for the fossil record.

But, finally, here's the real clincher to this already-disproved theory. (Perhaps you have spotted it by now, since it's been lurking there throughout the preceding discussion.) The reason carbon-leaching was suggested in the first place was to induce artificially large age measurements; and, the reason it needed to act "through other layers" was to induce an age discrepancy across the layers. But---even without the other noted failures---the idea falls flat on its face because it leaches the most carbon-14 out of the top layers and the least out of the bottom layers. In other words, the theory suggests that the top-most layers should be measured as being the oldest (since they're most deficient in carbon-14), and the bottom-most layers should be measured as being the youngest---exactly the opposite of what the global fossil record exhibits! (I exclude the relatively rare exceptions of geologic inversions. The only way I can immediately think of to circumvent this problem is to hypothesize some sort of global cavern immediately beneath the fossil beds, into which the Flood waters seeped. But, if that's the case, then how would the organisms die in such a way as to form the ceiling of such a cavern? Did they all levitate after they died so the water could get under them? They had to have something to rest upon in order to be deposited in layers. And, certainly it's not even remotely imaginable that such a widespread geologic phenomenon would leave no trace!)


Conclusion

Evolution explains the fossil record---which is nice, since it is so overwhelmingly mutually supported by everything else: biogeography, DNA evidence, and much more. But, then, it's not exactly a coincidence that what has actually happened is also supported by the evidence, and explains it.

On the other hand, creation and a flood cannot, under any circumstances, explain the segregated layering and different ages evident in the fossil record. I do not know if creationists subconsciously understand this and resort to lying and setting-up false dichotomies to "defend" their false beliefs, or if they are simply too dim or ignorant to recognize this fact. Regardless though, creationists cannot generate a single workable hypothesis to explain the fossil record, nor do they seem capable of identifying a legitimate complaint against the validity of evolutionary explanations.

Bottom line: creationists cannot explain the fossil record; evolutionists can. Creationists should simply admit they are wrong and relinquish their antiquated fantasies, letting them go the way of the flat Earth and geocentrism.

"It is far better to grasp the universe as it really is than to persist in delusion, however satisfying and reassuring." -Carl Sagan

2 comments:

Iron Soul said...

"That's right: you did not just read that sentence; you just think you did. Riiiiight."
This line of thinking has spawned one of my favorite parody religions: Last Thursdayism )http://en.wikipedia.org/wiki/Last_Thursdayism)

Reverted said...

I dunno, Jeff. I think I kind've like this sentence about creationists:

"They prance about, vividly displaying their abject ignorance with all the confident pomp of a strutting peacock during mating season, but with the fidelity and intellectual content of a peanut-replete turd."

(Incidentally, I think the turd may actually have greater intellectual content and fidelity! lol)