Dr. Fazale Rana of Reasons to Believe takes on a new paper that claims that the evolution can explain the Cambrian explosion.
They linked to this article from NBC News, showing how the paper was popularized.
The team found that the emergence of many sea creatures during the Cambrian explosion could be explained by an accelerated — but not unrealistic — evolution by way of natural selection, or the process in which organisms change over time due to changes in heritable physical or behavioral traits. (For instance, changes that give an organism a leg up will help it survive to pass down that trait to offspring.) The team focused its study on animals related to arthropods, the group that includes crustaceans and other insects.
“In this study we’ve estimated that rates of both morphological and genetic evolution during the Cambrian explosion were five times faster than today – quite rapid, but perfectly consistent with Darwin’s theory of evolution,” Lee said.
That’s the challenge. If you can’t listen to the entire podcast, then let me say that the problem with the paper is the way that they are measuring the “rate of change”. They are only measuring the rates of change in genes and phenotypic characters. They are not measuring other important requirements for the new body plans, like the network interactions and regulatory elements of the network. Also, they haven’t demonstrated a mechanism for even the rapid change they do measure in the genes and phenotypic characters.
Here’s is the MP3 file. (29 minutes)
The interviewer is Joe Aguirre and the scientist is Dr. Fazale Rana.
- JA: Does this paper explain the sudden origin of the Cambrian era fossils without the need for an intelligent cause?
- FR: The paper claims that the rapid rate of change in the Cambrian explosion is within the capability of Darwinian mechanisms
- JA: What is the Cambrian explosion?
- FR: Sudden appearance in the geological record of 50-80 percent of the animal body plans that have ever existed
- FR: Prior to that there were single-celled organisms
- FR: The only multi-cell organisms (Ediacaran fauna, etc.) are not precursors to the new body plans
- FR: This is not a diversification of plans from existing plans, this is about 30 new body plans
- FR: Not just body plans, but complex organs like eyes appear suddenly
- FR: The paper focuses on one body plan – arthropods (crustaceans, arachnids and insects)
- FR: The paper looks at anatomical features as well as genes
- FR: Paper says the rate of evolutionary change needed would be about 5 to 6 times the normal rate of change
- JA: Has the rate been the same since that time
- FR: No the rate of change we see is a fifth of what is seen in the Cambrian explosion, and it is constant
- FR: The claim is that the rate of change of 5X is anomalous, but is reasonable
- FR: The researchers established that what happened in the Cambrian explosion is unusual
- FR: The researchers just assert that the faster rate of change is plausible
- FR: They have not provided a mechanism for this faster rate of change
- JA: Has anyone come up with a mechanism for the higher rate of change?
- FR: No. There are speculations, but no one has published a robust, defensible explanation
- FR: They are saying, if you embrace the evolutionary paradigm, then the rate of evolution has to be 5 to 6 times faster
- FR: But they haven’t demonstrated a mechanism that can produce that rate of change, they just asserted that it’s no big deal
- FR: To me, a requirement for an accelerated rate of evolution is an argument for intelligent design
- JA: Why aren’t people working on the mechanism?
- FR: The Cambrian explosion happens at a time when Earth is exiting a frozen stage
- FR: The environment becomes hospitable to life as we exit this “snowball event”
- FR: But just because the environment is now hospitable, that does not mean that the genetic changes are automatic
- FR: On a Genesis creation account, the Cambrian explosion is described in the 5th day
- FR: God creates the new animal types when the environment can accommodate them
- JA: Can the naturalist explain how they go from single-celled organisms to compound eyes with 3000 lenses?
- JA: Why did evolution-agitator Eugenie Scott say that the Cambrian proceeded “at a leisurely pace”?
- FR: doing a calculation like from single cells to compound eyes is difficult
- FR: these visual systems are intricate and sophisticated, with respect to field of depth, resolution, etc.
- FR: additionally, the eye requires support systems in order to function
- FR: The Cambrian era goes from 540 mya to 490 mya
- FR: The two most important sites to study it are the Burgess Shale and the Chengjiang Valley
- FR: The Chengjiang site shows the earlier period of the Cambrian, and the animals are there in the first 5 million years
- FR: The period is at most 5 million years
- FR: We are talking about completely different body plans and architectures
- FR: It’s been shown that you cannot go from one body plan to another body plan, it will kill the intermediate forms
- JA: You have to explain how ALL of the phyla came in together in a short period
- FR: Yes. When evolutionists just assert that higher rates of change are “plausible” without specifying a mechanism, that’s not good science
Uncommon Descent had another response to the paper.
I’d like to make two very general observations here. First, measuring rates of change in existing traits is not the same thing as measuring the rate at which new traits appear.
Second, the rapid appearance of new body traits that occurred during the Cambrian explosion could never have taken place without a host of underlying changes at the genetic level. It is these changes that we need to explain. How do we explain, for instance, the sudden increase in the number of new cell types that occurred during the early Cambrian period? Lee et al. do not even discuss this question in their paper: a search on the phrase “cell type” turns up empty.
[...]In a recent post over at Evolution News and Views, Casey Luskin drew readers’ attention to a new book by paleobtologists Douglas Erwin and James Valentine, entitled, The Cambrian Explosion: The Construction of Animal Biodiversity (Roberts and Company, 2013). The authors, who are recognized authorities in their field, are no friends of Intelligent Design, but they firmly reject the standard neo-Darwinian explanations that have been put forward for the Cambrian explosion. In particular, they take issue with the claim that macroevolution is nothing more than an extrapolation of microevolution.
He then prints a few excerpts from the Erwin and Valentine book.
Increased genetic and developmental interactions were also critical to the formation of new animal body plans. By the time a branch of advanced sponges gave rise to more complex animals, their genomes comprised genes whose products could interact with regulatory elements in a coordinated network. Network interactions were critical to the spatial and temporal patterning of gene expression, to the formation of new cell types, and to the generation of a hierarchical morphology of tissues and organs. The evolving lineages could begin to adapt to different regions within the rich mosaic of conditions they encountered across the environmental landscape, diverging and specializing to diversify into an array of body forms.
Like Dr. Rana said, the new paper never takes these factors into account.
Reading through the introduction, it is readily apparent that Erwin and Valentine have thought long and hard about the issues relating to the Cambrian explosion, and that they truly appreciate the magnitude of the problem of explaining this seismic event in the history of life. By contrast, the new study by Lee et al. fails to grapple with the deeper issues: its aim is merely to defend Darwinism, and it “succeeds” only by shrinking the problem by focusing on minutiae such as rates of change in genes and phenotypic characters. No wonder, then, that the study’s authors perceive no threat to Darwinian evolution in the Cambrian explosion.
So should we be concerned about this paper? I don’t think so – not until they have a mechanism that can drive the required level of innovation. The paper pushes a naturalistic explanation, and so we are within our rights to ask for a naturalistic mechanism. Even if they had the mechanism, they still aren’t taking into account everything that needs to be explained – like regulatory elements in the coordinated network that Erwin and Valentine mentioned.
UPDATE: Kylie asked me a question that caused me to update this post. She asked me what about Behe’s work that shows that Darwinian mechanisms cannot even account for the NORMAL rate of change? I just want to be clear and say that I don’t think that Darwinian mechanisms can even account for that. What the paper does is assume that Darwinian mechanisms can account for the 1X “rate of change” they see. Then they further assume that evolution is able to do the 5X change rate as well. All they did was measure the amount of change and then assert that it’s not that far off of normal. But I don’t accept that Darwinian mechanisms can even do the normal rate of change, because of Behe’s book on the limits of Darwinian mechanisms to drive change.