Tag Archives: Darwinism

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New study: rising oxygen levels rejected as explanation of Cambrian explosion

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Christianity and the progress of science
Christianity and the progress of science

So, just to refresh everyone, the Cambrian explosion was an event that occurred about 543 million years ago. In a very short period of time, less than 10 million years, probably 3-5 million, all of the major animal body plans emerged.

Here’s what the Cambrian explosion looks like:

Cambrian Explosion
Cambrian Explosion

The Darwinian theory says that there should be precursors to all of the new phyla that appear. But we have never been able to find any precursors. We’ve been looking in the fossil record for the slow transition from simple life to complex life that Darwin predicted, but we’ve never been able to find anything that explains the sudden emergence of the body plans in the Cambrian explosion.

There is no known naturalistic explanation for the rapid emergence of these “phyla”. But, naturalists were holding out hope that maybe a sudden rise in the level of oxygen might have “triggered” the required increase in complexity.

This is from Science Daily.

Excerpt:

Oxygen is crucial for the existence of animals on Earth. But, an increase in oxygen did not apparently lead to the rise of the first animals. New research shows that 1.4 billion years ago there was enough oxygen for animals — and yet over 800 million years went by before the first animals appeared on Earth.

Animals evolved by about 600 million years ago, which was late in Earth’s history. The late evolution of animals, and the fact that oxygen is central for animal respiration, has led to the widely promoted idea that animal evolution corresponded with a late a rise in atmospheric oxygen concentrations.

“But sufficient oxygen in itself does not seem to be enough for animals to rise. This is indicated by our studies,” say postdoc Emma Hammarlund and Professor Don Canfield, Nordic Center for Earth Evolution, University of Southern Denmark.

[…]The new study is published in the journal Proceedings of National Academy of Sciences.

[…]The results differ from other studies and raise several questions, such as: Why then did animals rise so late in Earth’s history?

“The sudden diversification of animals probably was a result of many factors. Maybe the oxygen rise had less to do with the animal revolution than we previously assumed,” says Hammarlund.

Now look here. I don’t see how a rise in oxygen level can create new body plans. Body plans are written in sequences of symbols – in proteins and DNA. I can no more believe that a rise in oxygen levels could create new animal body plans than I could believe that raising the level of oxygen in a computer lab could explain the new code that is being written by the software engineers. Body plans are information, and new body plans require new information. Information comes from software engineers – intelligent agents – not from rising oxygen levels.

In any case, the hypothesis was falsified. It isn’t the first time a naturalistic hypothesis for the Cambrian explosion was shot down (see below) and it won’t be the last.

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Polemics

John C. Sanford’s genetic entropy hypothesis

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Christianity and the progress of science
Christianity and the progress of science

JoeCoder sent me a recent peer-reviewed paper by John C. Sanford, so I’ve been trying to find something written by him at a layman’s level so I could understand what he is talking about.

Dr. Sanford’s CV is posted at the Cornell University web page.

I found this 20-minute video of an interview with him, in which he explains his thesis:

The most important part of that video is Sanford’s assertion that natural selection cannot remove deleterious mutations from a population faster than they arrive.

And I also found a review of a book that he wrote that explains his ideas at the layman level.

It says:

Dr. John Sanford is a plant geneticist and inventor who conducted research at Cornell University for more than 25 years. He is best known for significant contributions to the field of transgenic crops, including the invention of the biolistic process (“gene gun”).

[…]Sanford argues that, based upon modern scientific evidence and the calculations of population geneticists (who are almost exclusively evolutionists), mutations are occurring at an alarmingly high rate in our genome and that the vast majority of all mutations are either harmful or “nearly-neutral” (meaning a loss for the organism or having no discernible fitness gain). Importantly, Sanford also establishes the extreme rarity of any type of beneficial mutations in comparison with harmful or “nearly-neutral” mutations. Indeed, “beneficial” mutations are so exceedingly rare as to not contribute in any meaningful way. [NOTE: “Beneficial” mutations do not necessarily result from a gain in information, but instead, these changes predominantly involve a net loss of function to the organism, which is also not helpful to [Darwinism]; see Behe, 2010, pp. 419-445.] Sanford concludes that the frequency and generally harmful or neutral nature of mutations prevents them from being useful to any scheme of random evolution.

[…]In the next section of the book, Sanford examines natural selection and asks whether “nature” can “select” in favor of the exceedingly rare “beneficial” mutations and against the deleterious mutations. The concept of natural selection is generally that the organisms that are best adapted to their environment will survive and reproduce, while the less fit will not. Sanford points out that this may be the case with some organisms, but more commonly, selection involves chance and luck. But could this process select against harmful mutations and allow less harmful or even beneficial mutations to thrive? According to Sanford, there are significant challenges to this notion.

Stanford is a co-author of an academic book on these issues that has Dembski and Behe as co-authors.

Now, I do have to post something more complicated about this, which you can skip – it’s an abstract of a paper he co-authored from that book:

Most deleterious mutations have very slight effects on total fitness, and it has become clear that below a certain fitness effect threshold, such low-impact mutations fail to respond to natural selection. The existence of such a selection threshold suggests that many low-impact deleterious mutations should accumulate continuously, resulting in relentless erosion of genetic information. In this paper, we use numerical simulation to examine this problem of selection threshold.

The objective of this research was to investigate the effect of various biological factors individually and jointly on mutation accumulation in a model human population. For this purpose, we used a recently-developed, biologically-realistic numerical simulation program, Mendel’s Accountant. This program introduces new mutations into the population every generation and tracks each mutation through the processes of recombination, gamete formation, mating, and transmission to the new offspring. This method tracks which individuals survive to reproduce after selection, and records the transmission of each surviving mutation every generation. This allows a detailed mechanistic accounting of each mutation that enters and leaves the population over the course of many generations. We term this type of analysis genetic accounting.

Across all reasonable parameters settings, we observed that high impact mutations were selected away with very high efficiency, while very low impact mutations accumulated just as if there was no selection operating. There was always a large transitional zone, wherein mutations with intermediate fitness effects accumulated continuously, but at a lower rate than would occur in the absence of selection. To characterize the accumulation of mutations of different fitness effect we developed a new statistic, selection threshold (STd), which is an empirically determined value for a given population. A population’s selection threshold is defined as that fitness effect wherein deleterious mutations are accumulating at exactly half the rate expected in the absence of selection. This threshold is mid-way between entirely selectable, and entirely unselectable, mutation effects.

Our investigations reveal that under a very wide range of parameter values, selection thresholds for deleterious mutations are surprisingly high. Our analyses of the selection threshold problem indicate that given even modest levels of noise affecting either the genotype-phenotype relationship or the genotypic fitness-survival-reproduction relationship, accumulation of low-impact mutations continually degrades fitness, and this degradation is far more serious than has been previously acknowledged. Simulations based on recently published values for mutation rate and effect-distribution in humans show a steady decline in fitness that is not even halted by extremely intense selection pressure (12 offspring per female, 10 selectively removed). Indeed, we find that under most realistic circumstances, the large majority of harmful mutations are essentially unaffected by natural selection and continue to accumulate unhindered. This finding has major theoretical implications and raises the question, “What mechanism can preserve the many low-impact nucleotide positions that constitute most of the information within a genome?”

Now I have been told by JoeCoder that there are many critical responses to his hypothesis, most of which have to do with whether natural selection can overcome the difficulty he is laying out. But since this is not my area of expertise, there is not much I can say to adjudicate here. Take it for what it is.

Positive arguments for Christian theism

Videos

Stephen C. Meyer and Marcus Ross lecture on the Cambrian explosion

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Cambrian Explosion
Cambrian Explosion

Access Research Network is a group that produces recordings  of lectures and debates related to intelligent design. I noticed that on their Youtube channel they are releasing some of their older lectures and debates for FREE. So I decided to write a summary of one that I really like on the Cambrian explosion. This lecture features Dr. Stephen C. Meyer and Dr. Marcus Ross.

The lecture is about two hours. There are really nice slides with lots of illustrations to help you understand what the speakers are saying, even if you are not a scientist.

Here is a summary of the lecture from ARN:

The Cambrian explosion is a term often heard in origins debates, but seldom completely understood by the non-specialist. This lecture by Meyer and Ross is one of the best overviews available on the topic and clearly presents in verbal and pictorial summary the latest fossil data (including the recent finds from Chengjiang China). This lecture is based on a paper recently published by Meyer, Ross, Nelson and Chien “The Cambrian Explosion: Biology’s Big Bang” in Darwinism, Design and Public Education(2003, Michigan State University Press). This 80-page article includes 127 references and the book includes two additional appendices with 63 references documenting the current state of knowledge on the Cambrian explosion data.

The term Cambrian explosion describes the geologically sudden appearance of animals in the fossil record during the Cambrian period of geologic time. During this event, at least nineteen, and perhaps as many as thirty-five (of forty total) phyla made their first appearance on earth. Phyla constitute the highest biological categories in the animal kingdom, with each phylum exhibiting a unique architecture, blueprint, or structural body plan. The word explosion is used to communicate that fact that these life forms appear in an exceedingly narrow window of geologic time (no more than 5 million years). If the standard earth’s history is represented as a 100 yard football field, the Cambrian explosion would represent a four inch section of that field.

For a majority of earth’s life forms to appear so abruptly is completely contrary to the predictions of Neo-Darwinian and Punctuated Equilibrium evolutionary theory, including:

  • the gradual emergence of biological complexity and the existence of numerous transitional forms leading to new phylum-level body plans;
  • small-scale morphological diversity preceding the emergence of large-scale morphological disparity; and
  • a steady increase in the morphological distance between organic forms over time and, consequently, an overall steady increase in the number of phyla over time (taking into account factors such as extinction).

After reviewing how the evidence is completely contrary to evolutionary predictions, Meyer and Ross address three common objections: 1) the artifact hypothesis: Is the Cambrian explosion real?; 2) The Vendian Radiation (a late pre-Cambrian multicellular organism); and 3) the deep divergence hypothesis.

Finally Meyer and Ross argue why design is a better scientific explanation for the Cambrian explosion. They argue that this is not an argument from ignorance, but rather the best explanation of the evidence from our knowledge base of the world. We find in the fossil record distinctive features or hallmarks of designed systems, including:

  • a quantum or discontinuous increase in specified complexity or information
  • a top-down pattern of scale diversity
  • the persistence of structural (or “morphological”) disparities between separate organizational systems; and
  • the discrete or novel organizational body plans

When we encounter objects that manifest any of these several features and we know how they arose, we invariably find that a purposeful agent or intelligent designer played a causal role in their origin.

Recorded April 24, 2004. Approximately 2 hours including audience Q&A.

You can get a DVD of the lecture and other great lectures from Access Research Network. I recommend their origin of life lectures – I have watched the ones with Dean Kenyon and Charles Thaxton probably a dozen times each. Speaking as an engineer, you never get tired of seeing engineering principles applied to questions like the origin of life.

If you’d like to see Dr. Meyer defend his views in a debate with someone who reviewed his book about the Cambrian explosion, you can find that in this previous post.

Further study

The Cambrian explosion lecture above is a great intermediate-level lecture and will prepare you to be able to understand Dr. Meyer’s new book “Darwin’s Doubt: The Explosive Origin of Animal Life and the Case for Intelligent Design“. The Michigan State University book that Dr. Meyer mentions is called “Darwin, Design and Public Education“. That book is one of the two good collections on intelligent design published by academic university presses, the other one being from Cambridge University Press, and titled “Debating Design: From Darwin to DNA“. If you think this lecture is above your level of understanding, then be sure and check out the shorter and more up-to-date DVD “Darwin’s Dilemma“.