Repost: Only in the light of evolution

There are two reasons I want to make a repost of a post from about a year and a half ago. First, it’s always interesting to go back and read old posts for me. From time to time I have no recollection of making a certain post, so when I see it, it’s almost like it’s brand new to me. I do happen to remember this one very clearly, but it is at least understandable why I was skimming posts from May 2009. Second, I average significantly more views now than I did a year and a half ago. I feel this post is a pretty important one, and now that more people can see it, I would like to throw it back up.

~~~

I am following a specific chapter in Jerry Coyne’s Why Evolution is True.

The fossil record: We should see fossils in a certain order if evolution is correct. They should go from simple to more complex overall, and the fossils we see in the most recent strata should resemble extant life much more than the fossils we see in old strata.

We should also see changes within lineages. We should be able to observe instances of gradual change in species that eventually leads up to either current species or at least to the time of extinction for these species.

Here’s a simple timeline of life’s history. Click it.

What the evidence shows is gradual change. First we find simple bacteria which survived off energy from the Sun, then we see more complicated cells known as eukaryotes arise. (You are a eukaryote.) Next we see a slew of multi-cellular animals arise. They’re still simple, but much more complex than the original bacteria. A few million years later more complicated life arrives. Early (and simple) plants begin to take hold. Soon the fossil record begins to show more plant complexity with low-lying shrub such as ferns, then conifers, then deciduous trees, and finally flowering plants. Gradual changes occur in the oceans and fresh waters which lead to fish and then tetrapods (Tiktaalik comes to mind).

One of my favorite fossils is trilobites. They’re extremely common due to their hard bodies. In fact, even their eyes are well-preserved because of their hard mineral make-up. I personally recall entering touristy-stores seeing countless fossils of these guys in the mid-west to the west (which, unsurprisingly, was once a shallow sea). This image shows the different lineages of this organism. Studies show that the ‘rib’ count has changed over time in each individual species, often without regard to how the other species changed. Going back further, there is less and less divergence in each species. Eventually, as evolution predicts, they all meet at a common ancestor.

So naturally the next step is to find fossils which show more significant changes. Let’s take birds and reptiles. They hold similarities between each other, both morphologically (certain shapes and structures) and phylogenetically (genetic sequence). A good hypothesis is that they came from one common ancestor. If this is true, the links between birds and its ancestors and reptiles and its ancestors should lead to the same point. They do. Dinosaurs are the ancestors of both. The links between birds and dinosaurs are so incredibly well established that I’d prefer to not go over them in detail. But for starters, some dinosaurs sported feathers and claws and had the same proteins for the feather-making process as extant birds. The links between reptiles and dinosaurs is easier just on intuition, so I’ll leave it at that for now.

Other transitional fossils include the already mentioned Tiktaalik. A view of the history of life can be see here. This shows the change in head and neck structure. Recent research on long-ago discovered Tiktaalik fossils has shown the importance in the gradual bone changes in the neck. These changes – a hallmark of evolution – were important to the ability to turn its head. This is a hallmark because natural selection only modifies what already exists. This is precisely what happened.

Going further with this example, evolution makes predictions as to how early fish evolved to survive on land. If there were lobe-finned fish 390 million years ago and obviously terrestrial organisms 360 million years ago (which is what the fossil record shows), then if scientists are to find transitional fossils, they should date in between that time frame. There should be an animal that shows both features of lobe-finned fish and terrestrial animals. Tiktaalik is that animal. It has fins, scales, and gills, but it also has a flat, salamander-like head with nostrils on top of its nose. This is a good indication that it could breathe air. Its eyes were also placed there, indicating that it swam in shallow waters. Furthermore, it was lobe-finned, but shows bones (which eventually evolved into the arm bones you used to get out of bed today) that were able to support its weight to prop itself up. And of course, it dates to 375 million years ago.

Next, evolution says the fossil record should show recent fossils being more closely related to extant species than are early fossils. This is precisely what happens. Sixty million years ago there were no whales. Fossils resembling modern whales only show up 30 million years ago. So, again, evolution makes a predication: if transitional fossils are to be found, they will be within this gap. And so it is.

We begin with Indohyus. It was an artiodactyl. This is important because extant whales have vestigial bones which indicate that they came from this order: scientists expected to find this because, again, evolution predicted it. It should be of no surprise that this fossil dates to about 48 million years ago, right in the predicted gap. From here there is a gradual evolution shown in the fossil record which leads up to modern whales.

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21 Responses

  1. The biggest problem with conventional evolutionary thinking is the lack of fossils showing the gradual change you mention.

    Although I think you mean gradual by taking into account the billions of years the earth has existed and the 3.7 (ish) that life has been on earth.

    Substantive changes happen extremely quickly (again in the context of the time frame) and tend to stick around for long periods of time. We just need to figure out why and how.

  2. There is plenty of gradual change shown in the fossil record. In addition, there are more substantial changes that occur around the mass extinction events, such as the end-Permian and the KT extinction. The marine fossils, in places show a very gradual change for certain species, particularly those with shells or corals, where they can actually see down to layers by single year, over hundreds of millions of years in fossilized sediments that cover many kilometers of depth. Land fossils, of course are not as finely laid down.

  3. Forgot to set Notify. Rectified.

  4. Phyletic gradualism is pretty much dead, that is that change occurs gradually and continuously. That’s all I was going for.

    I’m fond of Punctuated Equilibrium. I think it fits the fossil record best, but that’s just me. It’s important to note that the fossil record is actually pretty unreliable and that’s probably why why still don’t know how evolution really works.

    There is at least one other hypothesis out there floating around I can’t remember what they call it though….

  5. Maybe you don’t know how evolution works but many people do. There is natural selection and there is genetic drift and there is parasitism, etc. Punctuated equilibrium has pretty much been discounted for other hypotheses that cover it better.

  6. Also, as I stated and you ignored, the marine fossil record is massive, continuous and mostly complete.

  7. Yes Bob I’m here simply to argue with you, or at least you insist that I am here to do so.

    As you noted the marine fossil record is massive. Can you, perhaps, explain how one could know that it was complete? It is certainly not. There are gaps in everything, that’s not surprising given the extraordinary rarity of fossilization.

    Natural selection, genetic drift and parasitism (and co-speciation) neither prove nor disprove any of the evolutionary theories. They are simply possible mechanisms by which it happens.

    Punctuated equilibrium and punctuated gradualism are the only two models that make any sense at this point.

    I hope you were not trying to defend phyletic gradualism, a pretty impossible thing to do.

  8. I know Dawkins doesn’t like punctuated equilibrium. Plenty of scientists and archaeologists are on my side though, and since we don’t actually know, Bob, maybe you just cool your jets a bit.

  9. There are gaps in everything, that’s not surprising given the extraordinary rarity of fossilization.

    Marine fossils are not rare. You are confusing it with land fossils. There are literally tens of millions of trilobite fossils.

  10. I didn’t say any fossils are rare. Fossils are common.

  11. Oh, No! two more gaps for god to hide in:

    http://blogs.discovermagazine.com/80beats/2010/11/12/worlds-oldest-embryo-fossils-shed-light-on-dinosaur-parenting/

    Extinction events explain the jumps in evolution far better than punctuated equilibrium. I hope you won’t try to defend NOMA next.

  12. I am not seeing what God has to do with this discussion at the moment.

    I’m beginning to doubt whether you have any idea what so ever about what your talking about.

    NOMA?

  13. Steven J Gould, your punctuated equilibrium guy. You never heard of NOMA? Is that because you rely on headlines only? Yet another embarrassing thing that he has had refuted. Also look up spandrels and his mis-application of the term.

    I’m beginning to doubt whether you have any idea what so ever about what your talking about.

    You use YOUR ignorance to paint me with ad-hominen crap. Is that from your Catholic upbringing? Or is it just your lack of education?

  14. Sigh.

    Lets start closer to the beginning here. What theory do you subscribe to? There’s really only 3 choices (possibly 4 but, eh)

    AHA! non-overlapping magisteria! I certainly have, I’ve never seen an acronym in its place however, you could have just spelled it out instead of trying to twist it as if I’m some kind of country bumpkin.

    Finally what do you know about my education?

  15. Perhaps you should take a look at people like Ernst W Mayr.

    Punctuated equilibrium simply contends that species (usually) originate too quickly for normal geological processes to record the event. Like I said, fossilization is an extremely rare process.

    Its said that the species around today represent less than 1% of all the species ever to have existed on earth. We have somewhere in the neighborhood of 1.5 million (some say up to 10 million or more but who knows) species in existence today. Yet in the fossil record has only about 250,000 species represented.

    The problem is that evolution in its entirety is untestable. Fossilization is too rare to have recorded every organism that has ever lived. This leaves us with 3 (major) choices.

    Gradualism: Evolution is continual and ever changing and happens over millions of years to produce new species. The fossil record simply records this progress at intervals and leaves us with big gaps. Given that small populations are more likely to pass on genetic mutations and small populations are less likely to fossilize, the absence of transitional fossils is not surprising. (we have very few)

    Punctuated equilibrium: Evolution happens in quick bursts (tens of thousands or hundreds of thousands of years) and species remain relatively unchanged until extinction or a subsequent evolutionary event leads another branch. The fossil record shows us what we would expect. The exceedingly small portion of organisms fossilized are almost never caught in those short transitional periods.

    Punctuated gradualism: Somewhere in the middle of the above two.

    Again the problem is we are unlikely to discover the answer. If you want to make assumptions than gradualism works fine.

    If you want to rely strictly on the evidence we have (punctuated equilibrium would still give us some transitional fossils, but very very few) than punctuated equilibrium matches with the evidence.

    If you assume some tenets of both are true than punctuated gradualism fits pretty good. It however requires the assumption that gradualism happens commonly enough.

    I’m going to be on the road starting tomorrow afternoon until Tuesday and I’m not likely to have a chance to reply, Bob. I just thought I’d give you something else to chew on while I am away. Even though you haven’t replied to my last post.

  16. So much nonsense from you Nate. Most of it irrelevant to the topic so it will be ignored. You like to throw extraneous stuff in because you have little facts to use for your arguments. Keeping to the topic:

    The problem is that evolution in its entirety is untestable.

    Darwin published the theory of evolution 150 years ago when there were hardly any fossils at all. He did it by relying on evidence of many other disciplines. Since that time that evidence, as well as the hundreds of thousands of fossils have continuously bolstered his main theory. Many disciplines have shown evidential support, including bio-geography, geology, embryology, Mendelian inheritance, and especially molecular biology and DNA. The evidence is overwhelming and is more evidence than exists for the theories of gravity or any other theory. If you, Nate, want to continue to doubt it, that’s your right, but, of course someone who believes in the woo of virgin birth, resurrection and infallibility of a criminal pope upon no evidence whatsoever can just be discounted and laughed at.

    Even though you haven’t replied to my last post.

    I never called you a country bumpkin. I have seen the acronym used all over the place. Again, you use your ignorance to disparage me. I guess this is a theme now. You are the one hurling ad hominems and therefore deserve no response other than responding in kind.

  17. I see this playing out like every other argument we have bob. Let me draw you a picture.

    I say something that if stretched could be considered a personal criticism.

    You go off the deep end and throw a half dozen clear cut attacks back at me.

    For example:

    I said: “I’m beginning to doubt whether you have any idea what so ever about what your talking about.”

    And so I was. It was perfectly true. You responded like this:”You use YOUR ignorance to paint me with ad-hominen crap. Is that from your Catholic upbringing? Or is it just your lack of education?”

    Which is remarkable because typically you lead with that sort of bilge being the main body of you argument.

    As far as the NOMA thing, who cares? I didn’t recognize it. You made a rather sad attempt, as usual, to make a claim that I am ignorant. This time based on my not recognizing a single acronym have little or nothing to do with the topic at hand.

    Further you keep throwing in little interjections about my religion, which I haven’t mentioned, has no bearing on the topic as we have been discussing it and frankly is an extremely boring way to be attacked over and over. At least be creative.

    Not to mention that after calling me ignorant you made some kind of allusion to my education! What does your education consist of? What would it matter anyway? A degree doesn’t mean you know a damn thing, it means you passed tests and wrote reports. After which its all free to leak out of your head, which often times happens.

    So again, tell me about my crappy education.

  18. If you didn’t care about NOMA, then why did you make a big deal of it? Hypocritical.

    I don’t care about your education. Again, you make a big deal about one comment that responded to your ad hominem. Go suck an egg.

    You rarely stay on a topic, you are usually all over the place. This is usually due to not be able to actually address an issue so you disseminate and obfuscate and hope that no one notices. There are probably eight instances of it in this thread. It is tiresome to see the deviousness. Go suck another egg.

    Since you have had no effective argument in this thread. It is finished as far as I am concerned and I will unsubscribe, so you can rant and rave yet again.

  19. Getting to topic.

    I didn’t say evolution was wrong, I said it was untestable in its entirety.

    We can test parts, but parts only. That’s a problem. You are right that there is a mountain of evidence for evolution. There is not a mountain of evidence for gradualism.

    Evolution is clearly a process that is happening and has happened. Thank you for pointing that out, but we would be having a very different discussion if I was trying to say that evolution is false.

    Your also right about the fossils but wrong about what your trying to say. The fossil record contains millions of fossils, however they are representative of only about 250,000 species. Out of a theorized 150,000,000 species (some estimates in the billions) that’s not a very good representation.

    You’ll probably just say, again and wrongly, that everything I’ve said is irrelevant. Than you’ll probably call my mother names to prove that point. You haven’t done that yet, maybe it will prove you right if you do. I have my doubts, but feel free.

  20. But you have unsubscribed, oh well. I feel bad that you always run off instead of taking your point to task.

  21. Yet another example of how evolution is a proven fact and that Nate has his head up his ass.

    There have been testable projections that have been proven. Time and time again and here is yet another of the thousands of cases:

    http://blogs.discovermagazine.com/notrocketscience/2010/11/15/evolutionary-trees-help-to-convict-men-who-knowingly-infected-women-with-hiv/

    Go suck more eggs!

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