The Cambrian Explosion And Evolution

https://www.cell.com/current-biology/fulltext/S0960-9822(15)01177-X

This is an important paper that I don’t see being discussed too much

It is important to provide more context. At minimum, put the title of the paper and the abstract, if not a few key quotes and figures.

Have you even read my response? How long do you think this amount of time was? How much change do you think was?

I try to. I copy and paste stuff and it appears then disappears after I hit reply. Don’t knkw if it’s my phone or what

I don’t believe I did. I don’t even think your response was up yet when I hit the reply button to @T.j_Runyon (who I will be in my prayers tomorrow, and whom I will miss around here, and with whom I agree that his second link was an important paper that did not get enough attention), so I likely did not even see it at the time.

I don’t doubt that what you say is true Joshua, but I hope you understand that the result is consistent with what you would expect to find if what I or @jongarvey propose is the way that it happened.

Consider these two highlighted findings from T.J’s second link…

•Molecular clock analysis indicates an ancient origin of animals in the Cryogenian
•Diversification into animal phyla occurred in the Ediacaran, before the Cambrian

If their analysis is correct then the differences in genetics began much further back in time than the fossil evidence indicates- that’s one interpretation. Another interpretation is that the changes occurred at the rate the fossils say that they did but that the rate was much much higher than the rate we observe now. And this is what I have been pointing to all along wondering if there are not spots where the earth “had help” with evolution.

Now it could be as I think you are saying- that the genetic clock just doesn’t work at these kinds of distances. That would also be consistent with what I suspect (based on the text of early Genesis more than the science at this point in time). Molecular genetics works better for more closely related groups than for more distantly related groups because the former probably really did evolve from a common ancestor via known evolutionary processes. Or perhaps only a Divine nudge here or there was required. As you move further out, common ancestry via natural descent doesn’t show up in the numbers as well because there was a lot less of it.

Now what I just wrote is only my speculation on the evidence. As you point out, there may be limits on what the tools can tell us and this is all that we are seeing here. The limits of scientific inquiry is one of your themes I believe, and I share it to a large extent. Yet while it is not overwhelming evidence for one position or the other by any means, it is a data point. And this one happened to come down on the side that the changes occurred faster than we might expect based on known natural processes.

Maybe we just don’t know enough yet. Maybe we will find out the clock is wrong or maybe we will find the fossils were there after all, but based on what we know right now, we have a data which seems to suggest that known evolutionary processes have a rate problem when it comes to the “Cambrian Explosion”. Perhaps science will reconcile the clock to the fossils with more research and I am all for that effort. Right now though, those two conclusions are where they are now.

This is just finding patterns in the noise, based on very unclear measurements. We do not know from the fossil records how animals diversified before they had hard parts to appear in the fossil record. Moreover, the molecular clock becomes less valid the father back we go in time.

This is not an argument against God’s action, but it is an argument against the notion that this actually suggests His action. It just does not. This is not a problem, unless we just ignore all the the things we do know, and the critical uncertainties.

That is right.

It is not evidence against evolution. Period. Of course, it is also consistent with special creation too, because special creation is consistent with any observation. The original question, to be clear, was about whether or not this is a “problem” for evolution. It is not a problem.

No, as I’ve explained, we have given several reasons why this not a problem. We do not expect non-calcified animals to leave their remains, and we have already discovered fossil evidence of their existence (e.g. burrows). Your argument is just missing the point.

That is a key point. All these problems go away when we look at human evolution from common ancestors with the great apes. This happens starting 6 million years ago, stretching to today, rather than just under 600 million years ago.

If God made humans with common descent, there is zero reason to object to him making other animals by common descent. There is precisely zero people arguing simultaneously that (1) Cambrian explosion was not be common descent, but (2) human evolution was by common descent. That would be a totally incoherent position. This is why it makes most sense to focus on human evolution, where the theological challenges are greatest, and the scientific evidence is strongest.

@swamidass
Purely out of curiosity, do we have photographs of these burrows (or are they too small to see)? It would be interesting to see some diagrams etc. as well…I may search out some of those things to post…

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Fascinating! Thanks for sharing!

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40 millions years is well more than half the time between the dinosaur extinction and present day. That’s a long time.

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Why do I get the feeling that if the clock data had matched up with the fossil data it would be hailed as “a stunning confirmation of evolution”? Maybe because on the occasions on which it does, it is. But the clocks don’t work across large genetic distances. This paper is not the only one to point that out. Micheal Behe did the same in “Darwin’s Black Box”. It is very possible you are right about why, but more on that in a bit.

If indeed this is just a limitation on the science of genetic clocks then its not a problem for evolution. Or if its just a limitation on fossilization of myriads of diverse creatures that were there but didn’t leave traces its not a problem for evolution. You seem utterly convinced of both, but I don’t see the basis of your certainty.

Surely you see the circularity in the belief that since these measurements fail to confirm known evolutionary processes the measuring sticks must be broken? The failure to confirm evolution by known processes is not de facto proof that they are flawed instruments of measurement (but accurate instruments when they confirm evolution by known processes).

You have advanced several explanations as to why this is not a problem. I’m just saying if we can test these explanations more and they check out then they would become more convincing than if we test them less. We may not expect non-calcified remains as the norm, but they still happen under low-oxygen conditions with rapid burial.

Which are far later in the fossil record than the times indicated by the molecular clock data. Therefore isn’t it so that even if those are burrows left by “worms” and those worms gave rise to every body plan that popped up in the Cambrian they still show up too late to fit the molecular clock data in the paper TJ posted with the fossils? I will show the diagram from that paper below…

So really the clock has to be wrong to make your case, doesn’t it? Those “burrows” are still too late. If the clock is not broken then those things “evolved” too fast compared to the rate for known processes.

Well now that is a very strong point. I agree with you that this would seem incoherent. I don’t think that this is what happened. It is very late and I’d like to sleep on this one. Good night all.

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And in Human evolution, there is just an immense amount of evidence for it, with far more certainty than we see for the Cambrian Explosion. You do not have to agree with it, but that is the place to focus the conversation if you want to get to the bottom of what the evidence shows.

@anon46279830,

I find it most odd that you work so hard to oppose speciation. Do you oppose speciation in principle? Or do you allow for speciation when there is “enough time for it to occur”?

Part of the circumstances of a Genetic Clock is now quickly environmental factors can change in a way that brings some new genetic factor or allele to the forefront. We aren’t even clear on how entrenched gender differentiation applied to some of these weird monsters of the Cambrian Age.

Sexual Reproduction was a way for creatures, who had developed strong mechanisms for precise DNA replication to still introduce novelty into each generation. Prior to the arrival of Sexual Reproduction, you can imagine how “self-cloning” could lead to dozens of new populations… each with their own genetic properties… exploring all sorts of niches and micro-niches.

But as these life forms also evolved more precise replication mechanisms, they started losing their flexibility. The accident of Sexual Reproduction became a survival technique all its own.

I don’t oppose speciation.

@anon46279830

So do you think God individually created all these hundreds of species … some wormy, others blobs of jelly, others like shell-fish with jaws of death? To what end do you pile up this skepticism about the one epoch that we could almost imagine God treating as a giant chore?

Just a reminder that when you are infinite and omipotent there is no work that is a chore - Aquinas was very keen to point that out when people baulked at God’s being a micro-manager (yes, that accusation was alive and well in the 13th century).

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George my children play this game on the computer. I can hardly get them off of it. In the game they get to select traits for new “life forms” and then guide them in the “wild”. At certain points they get to add other traits. It seems to me that if we humans do that for fun then our Template in whose likeness we are created might enjoy it as well.

What I get from the text of Genesis chapter one is that there is a realm below and a realm above. When God speaks, the realm above responds to it just as He intended quickly and perfectly. The land brings forth creatures itself, without His further intervention. It would be like theistic evolution if seen in slow motion. In this realm, things are in slow motion. Like us, this creation responds to His word slowly, haltingly, and with many errors and misteps along the way. And like us, without His intervention it couldn’t do it at all.

That’s how I read the text, and so I am looking for His “fingerprints” where nature had to get help. Just to get the ball rolling mind you. Nature took it from there. This event, where new 70 phyla show up within 4-8 million years, is a good candidate. I mean things don’t change that fast with known processes do they?

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@anon46279830

Continuing the “chore” aspect, I remember Tony Campolo picturing God making the first daisy, and then in delight saying, “Let’s do it again!” And so on ad infinitum.

It’s puerile, of course, but underlines a key truth about the God of the Bible - he loves infinitely what he has made, so that anything a human might care about, he cares about (and for) more. And that goes beyond just andwering prayer about insignifant little Jimmy.

Someone likes grand scale cosmology? God is as big as the cosmos. Someone else studies particle physics? God is involved in each particle. Or someone is one of those geeks doing taxonomy on near-identical mosquitoes, and boring everyone with his enthusiasm for these “wonderful creatures”? He’s only thinking God’s thoughts after him, or a pale reflection of them.

I can’t imagine that God is less interested in anything than I am.

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@anon46279830

Did you read my prior post at all?

Imagine a world where creatures reproduced by asexual cloning. Imagine what that means. It means that in the very beginning, each creature has the potential of starting its very own “population” of successors. Genetic changes that affect one clonal creature has zero effect on any of its cousins… it can’t, right? There is no sexual reproduction.

And so instead of having a few large populations, functioning as dampeners for any genetic novelties (the larger the population, the more dampening there is)… what we have instead is:

… hundreds and thousands of initially similar populations of descendants. And every generation, for these thousands of populations… the potential to differentiate from the common ancestor continues to proliferate.

This is because in the beginning, the replication of DNA for the next generation is very likely to be a little sloppy. So… try as life may to recreate the new generation to be identical to the existing generation, there really is no reliability to this process (in comparison to what sexually reproduced life forms of the current Earth are capable of).

In other words… these populations begin to fill all the niches of the Earth with highly diverse genetic profiles… because the early life forms weren’t very good (in a relative sense of course) at precise replication. But like all Natural Selection, the ability to reliably replicate genetic information becomes better and better.

But this opens up Earth’s life forms to the opposing force… that the more a population improves it’s ability to precisely replicate genomes, populations become increasingly uniform. And this is actually a liability in a world where Environmental factors continue to change in lots of different directions.

The populations that used to fill myriad niches easily (because of sloppy replication) are now becoming so uniform, they are more easily wiped out without any straggling survivors because of the lack of diversity.

At some point, life forms that developed sexual reproduction, begin to step into the limelight. It becomes the principle way that certain classes of life forms maintain adequate levels of diversity - - without going overboard.

In my view, the Cambrian was the time of going overboard… the natural result of a tremendous number of inevitable dead-ends. How do we know most of these lines are dead-ends? Because they disappear!

Now, of course, being a good BioLogos supporter, I am perfectly delighted with the idea that the Cambrian “expansion” (instead of explosion) was God-Guided. Your objections about the Cambrian seem to be arguing that Darwinism couldn’t accomplish this.

I would agree. So what’s your point? Even BioLogos folks chase the red herring of Darwinism. But you shouldn’t be the one to throw the red herring. Most of us concur that God-Guided evolution … even in the Cambrian.

So… you must be quite relieved, yes? And my discussion above gives you a sense of how God did it… by creating a lot of different life forms that created (de-facto) a great number of unique populations because widespread asexual cloning automatically makes that possible.

That is not at all my point. Are you sure you heard me?