Sunday, March 6, 2011

WEIT: The Big Picture

I'm spending a bit longer on Chapter 2 of Why Evolution Is True than I was planning to, but I want to quickly go back to something I skipped over: the overall fossil pattern found within the geologic column.

In the very lowest reaches of the fossil record we have very simple photosynthetic bacteria from roughly 3.5 billion years ago. Further up we find the more complex eukaryotes (~2 bya), then basic multicellular organisms like worms and sponges (~600 mya). Around 400 mya we find tetrapods, then amphibians (~350 mya) and reptiles (~300 mya). Closer to the surface we find mammals (~250 mya) and birds (~200 mya). Humans can be found only at the very top, only about 7 mya. Plants follow a similar pattern: "The oldest are mosses and algae, followed by the appearance of ferns, then conifers, then deciduous trees, and, finally, flowering plants." Below is a depiction of the latter (upper) part of the fossil record:

Coyne also provides some detailed small-scale examples from deep within the fossil record, showing that ancient plankton and trilobites changed slowly over periods of a few million years. He summarizes the "big picture evidence" as follows:
"Simple organisms evolved before complex ones, predicted ancestors before descendants. The most recent fossils are those most similar to living species, and we have transitional fossils connecting many major groups. No theory of special creation, or any theory other than evolution, can explain these patterns."
And he's right. He doesn't mention the creationists' attempts to explain them, but as with their massively flawed explanation of continental drift, I don't blame him. How do creationists explain the exquisite ordering of fossils throughout the geologic column? Their answer once again is essentially "the Flood did it." Basically, they think that denser creatures that lived at lower altitudes would be fossilized at the bottom, and less dense creatures living at higher altitudes would be at the top. They also think dumber, slower animals would be buried more quickly and deeply than smarter, faster animals. It makes just enough sense to convince the creationist crowd, but it's laughable to anyone who thinks about it critically for a few seconds.

I wonder if the creationists can tell us why fossils of helpless infant specimens are buried at the same level as their intelligent, mobile adult counterparts. If their ideas are correct, I wonder why birds, which have hollow bones and could fly to escape the flood waters, aren't virtually all found at the very top of the geologic column alongside humans. I wonder why the land mammal and early whale transitional Indohyus, which has unusually dense bones, didn't sink significantly deeper than other similar creatures. I wonder why we observe the delicate small-scale plankton and trilobite patterns that Coyne mentions in spite of the upheaval and chaos that would accompany a global flood. I wonder why we don't find a single fossil rabbit in the Precambrian.

The principles that the creationists propose are so weak that even if they were true, we would still expect there to be a huge standard deviation in burial point. There should be outliers: a few humans and penguins and flowering plants that for one reason or another were buried much deeper than the rest. Yet the fossil record is far too consistent for their ridiculous sorting mechanisms to account for. So I guess I'll continue to wonder how creationists can ever hope to explain away all the problems with their claims—I don't expect decent answers from them anytime soon.


  1. if we started off with single celled organisms how did that transition over to creatures such a seaweed ans sea sponges?

  2. so i have read through your page and to be honest i find no huge fact section within your writing apart from your photos,(if those can be called fact) rather that "being moved by the flood", as u so put it, another reason for the creatures to be on all the continents, at the same time in the fossil record is because they were created and not placed in one specific area, but rather spread among this world.And please enlighten me on what you would characterize as a simple organism. Because if asked what you how the eye was formed how would you explain that to me, i truly want to know your input, rather than read this "website" that rather than state "facts" actually bashes creationists with a stereotypical point of view
    as well as telling me do u know the difference between Micro and Macro evolution, and please, tell me the truth rather than those two words in your response

  3. please, honest check out the website and read all the way through

  4. Anonymous,

    Welcome. That's quite an assortment of questions you have! I'll try to answer them as briefly as possible.

    First you say that creatures were "spread among this world." I'm not quite sure of the point you're making here. This post is about the geologic column, not the worldwide geographical distribution of life. Next you ask the following:

    1. How did unicellular organisms evolve into seaweed and sea sponges?
    Based on your link, I suspect that your objection here is related to the Cambrian explosion. First, realize that the life we find from 600 million years ago is far more primitive than what we see today. Second, keep in mind that Precambrian life generally lacked parts that could easily fossilize. And finally, in spite of this, we do have evidence of basic multicellular organisms that preceded both algae and sponges, as well as silica spicules like those of sponges dating to 750 mya.

    2. What would you characterize as a simple organism?
    Certainly none of the organisms we see today! In fact, the simplest of organisms would not even be a basic prokaryote (lacking a nucleus and organelles), but rather a self-replicating molecule—perhaps a precursor to RNA.

    3. How was the eye formed?
    It began with a patch of light-sensitive cells. This patch became concave to sense direction. Then it folded in on itself to make something like a pinhole camera. Next the inside filled with viscous some of which solidified to form a lens, and tiny muscles attached to the lens for focusing. It's actually pretty simple, and we have living examples for each of these steps to prove their viability.

    4. What's the difference between microevolution and macroevolution?
    Basically it's evolution on a small versus a large scale, but there's no impenetrable barrier between the two, despite what creationists claim. We've directly observed the formation of new species and new biological features; the only factor that prevents us from observing even more dramatic changes is time.

    I skimmed through your link, and it looks like a rehash of a lot of the common creationist claims, along with a grab bag of out-of-context quotes. I would advise checking out the Talk Origins Archive and PhyloIntelligence; they provide answers in much more detail than I'm able to give here.

  5. i'm shocked that you can even say that the creation of the eye is simple in any terms and you did not quite answer my question on how unicellular organisms transformed into multicellular organism, it is completely understandable that they may be unable to fossilize but how do u explain to me that we jumped from unicellular organisms over to sponges and is "we" have this evidence then please provide me with some. also if these structures did transform then where is the transformations from "simple" to a trilobite Micro evolution is the"most fit" theory which i agree is completely true. but Macro evolution is life stemming from "simple" organisms and some how making there way over to what we see today. micro evolution does not interfere or bother with how it all started but macro evolution does, so there is a significant difference. also i would encourage you to read the portion of the url i gave you that explains how the structure of and eye for example is not so simple. i would like you to investigate the structure of a bacterium flagellum, which has the complex structure of the motors we use today, this complex motor is hard to investigate and still believe it was formed by the structure of proteins which are formed from the precise formation of amino acids and if an amino acid structure is not correct the cell will end up trashing the amino acid structure
    also if you know of reasons why you believe macro evolution is true i would prefer to read about it rather that read your bash on creationists
    also the organisms could have spread by previous formation, Pangaea, as well has humans migrating from place to place bringing with them animals, similar to humans carrying diseases

  6. Hi Anonymous,

    First of all, please make paragraphs. Putting all your text in one big block makes it a pain to read. Second, you're putting forth a lot of objections in a very small space. I would prefer it if you stuck to the few issues that you most want to discuss; otherwise we won't get very far with any of them. And third, I get the impression that you didn't check any of the links I gave you in my previous post; they're there for your benefit and back up my points.

    I'm sorry I wasn't clearer in what I meant by eye evolution being "simple"—the term is of course relative in this context. The process of eye evolution is straightforward, linear, and fairly well-understood. Hopefully that makes more sense.

    You wanted evidence for the evolution of early life. Click the "Early Life" tab on this page.

    The definitions of "micro-" and "macroevolution" you're using here are not, to my knowledge the ones used by working biologists, but rather are the ones used mainly by creationists.

    I'm quite familiar with the arguments about irreducible complexity with regard to both the eye and the flagellum. This video gives a fantastic explanation of why they (as well as others) don't hold water.

    Of my time spent discussing evolution, relatively little of it falls into the category of "bashing creationists." This post is just one in a series discussing the evidence for evolution, including what you would call "macroevolution."

    And finally, I still think you're missing the point with your examples (i.e. "humans bringing animals"). I don't see how they're supposed to explain the ordering of fossils within the geologic column. You seem to be talking about biogeography—which, while interesting, isn't really what I discuss in this post.

    If you're looking for a site that succinctly lays out the evidence for evolution, I would again recommend PhyloIntelligence or Talk Origins (especially this page).