The Cambrian Explosion And Evolution


(Jonathan) #1

The “Cambrian Explosion” has been said to be a problem for evolution…Is this the case?


Cambrian 'Explosion' - "Hypoxia-Inducible Factors" & Surviving Oxygen Surplus
A Genealogical Adam and Noah
(George) #2

@J.E.S, no. Not really a problem. YECs try to say that there wasn’t enough time for all these life forms to evolve so quickly. But without the genomes, there’s really no way to prove or disprove such an accusation.

[See below for an abstract of an exciting article on Oxygen levels being a driving component of the Cambrian Explosion! … Great graphic in the article!


(Jonathan) #3

In a way, this question comes down to: can evolution pragmatically work?


(George) #4

I suppose you could use the word “pragmatic”. A person could support the theory of speciation… but find its actual occurrence to be more difficult than researchers think it is.

But usually the objection is that speciation is theoretically impossible … Because Chromosomes are Stubborn?


(S. Joshua Swamidass) #5

@J.E.S, thanks for the question. No, the Cambrian Explosion is not a problem. There is a lot of confusion, first of all, about:

  1. How long it lasted (this “sudden” explosion) was more than 40 million years.
  2. The complexity of life during the explosion (there way high diversity, but also these were primitive animals).
  3. The complexity of life before the explosion (we see evidence, such as burrows, of soft-bodied animals of comparable complexity before).
  4. The climate changes at the time (which might have suddenly enabled a bunch of animals to form calcified parts, which is why we see their remains).

For all these reasons, it is really hard to call the Cambrian Explosion an “explosion” or an unsolved puzzle. When you are looking at a geological formation, scanning across rocks formed over the course of millions of years in a second, it certainly might look “fast” (perhaps @T.j_Runyon can comment), but 40 million years is certainly not “fast” as I understand it.

We have more than enough information about this time to be untroubled about it. Of course, we do not know all the details. No one does. Maybe God did intervene at times (evidence does not tell us one way or another). However, it is very hard to see this as evidence against common descent, or even unguided evolution.


(Vincent Torley) #6

Hi everyone,

Here’s a recent article which may be of relevance to the present discussion:

Scientists Reconstruct the Genome of the First Animal by Jordi Paps (Real Clear Science, May 4, 2018)

Our results suggest the genomes of the first animals were surprisingly similar to those of modern ones, containing the same proportions of biological functions. Around 55% of modern human genes descend from genes found in the last common ancestor of all animals, meaning the other 45% evolved later…

… We discovered the first animal had an exceptional number of novel genes, four times more than other ancestors. This means the evolution of animals was driven by a burst of new genes not seen in the evolution of their unicellular ancestors…

Finally, we looked at those novel genes from the first animal that are still found in most of the modern animals we studied… These novel genes that are still widely found today control essential functions that are specifically related to lifeforms with multiple cells. Three groups of these genes are involved in transmitting different nervous system signals. But our analyses show that these genes are also found in animals that do not have a nervous system, such as sponges. That means the genetic basis of the nervous system may have evolved before the nervous system itself did.

And here’s the technical paper it’s based on:

Reconstruction of the ancestral metazoan genome reveals an increase in genomic novelty by Jordi Paps and Peter W. H. Holland (Nature Communications, 1730 (2018), doi:10.1038/s41467-018-04136-5)

Jordi Paps is a Lecturer at the School of Biological Sciences, University of Essex.

Thoughts? @swamidass?


(S. Joshua Swamidass) #7

My thoughts are that this is a genetic analysis that has very little to do with the Cambrian Explosion.

It is also widely known that several essential elements of animals have a very deep history, so far in the deep past the details will always be murky and intermediate forms (especially of molecular elements) will often be long lost.


(Mark M Moore) #8

I’d say its a problem but whether they admit it or not is a separate question. Even if evolution can do everything they say it can given enough time, this is one of the prime places I have to point to and say “what mechanisms do we know about can cause THAT MUCH change in that amount of time?”

I know millions of research dollars have been spent hoping to eliminate or reduce the rate problem they have here, with some progress but not nearly enough IMHO. And I don’t begrudge them trying but it still looks from here like a prime candidate for the Fingerprints of God.


(T J Runyon) #10

https://www.nature.com/articles/s41467-018-04195-8

This paper came out just a few days ago


(T J Runyon) #11

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


(S. Joshua Swamidass) #12

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.


(S. Joshua Swamidass) #13

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


(T J Runyon) #14

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


(Mark M Moore) #15

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.


(S. Joshua Swamidass) #16

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.


The Explanatory Power of Darwinism
(Jonathan) #17

@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…


(S. Joshua Swamidass) #18


(Jonathan) #19

Fascinating! Thanks for sharing!


(George) #20

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


(Mark M Moore) #21

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.