Attempts to explain away the problem of the Cambrian explosion have continued since Darwin fist recognized the issue. The Cambrian explosion, and the Precambrian mini explosion before it, pose a direct challenge to evolutionary theory because the life forms that appeared in those relatively shorts periods of time arose suddenly and without apparent ancestors, at least as revealed in the fossil record. That they appeared suddenly defies the evolutionary necessity of long periods of time of gradual evolutionary change. That they appeared without apparent prior ancestors, obviously, negates the idea of an evolutionary tree altogether.
Darwin assumed that subsequent discoveries would fill in the gaps. Subsequent archaeology, far from filling in the gaps, has only exposed the gap to be wider than first believed. The gap in the record before the Precambrian period and the much wider gap from the Precambrian period to the Cambrian remains. The “lost” intervening fossils have never been found and are not likely to be found; so, other explanations are needed to sustain Darwinian Theory.
That is the subject of chapters 7-8 of Stephen C. Meyer’s book, Darwin’s Doubt. I lay out the basic problems in the first article in this blog series exploring chapters 1-4, and dig deeper into the problem Meyer explores in chapters 5 & 6 in a subsequent article. In this third article in the series, we dig deeper and wider still looking for possible solutions to the dilemma that still remains.
We begin with “punctuated equilibrium” as a possible solution. Niles Eldridge seized upon the idea and coined the phrase after observing that the long periods of stasis suggest the possibility that evolutionary change happens much more quickly than previously thought, so fast that the progression of the change may not be captured in the record. Eldridge developed the idea of “rapid speciation” (following these long periods of stasis), which would certainly be a convenient answer to the problem, but attempts to confirm it have proven problematic.
In searching for a “fast evolution engine”, Eldridge and Stephen Jay Gould proposed that change occurs rapidly at the species (macro-evolutionary) level. They called this “allopatric speciation”. Models made to demonstrate rapid speciation at work, however, proved to be incapable of the task.
“[A]llopatric speciation requires too much change too quickly to provide the theory of punctuated equilibrium with a biologically plausible mechanism for producing new traits or forms of animal life.” (p.147)
The reasons why are explored in some detail in Chapter 7 of Meyer’s book.
Another problem is that the process proposed by Eldridge and Gould assumes species and traits that were already existing, without any explanation of the origin of the species and traits necessary to make the process work. It turns out that their answer begged the very question they sought to answer.
This is also a fundamental problem with Darwinian Theory: natural selection works on traits that already exist; natural selection does not create the traits on which it necessarily depends to work. Richard Dawkins has said of this point:
“Nobody, not even the most ardent species selectionist, thinks that species selection can do this [explain the origin of complex new traits].”(quoted at p. 148)
James Valentine and Douglas Erwin agree that the “contending theories of evolutionary change at the species level” are not plausible explanations “of the origin of new body plans”. (quoted at p. 151) So, what’s next?
Darwin favored the idea of blending inheritance, which is the idea that existing traits blend to form new traits. The range of traits that could arise from the blending of existing traits, however, is necessarily limited by the existing traits that are blended. Meyer demonstrates how this theory could only lead to “a bland, homogenous, variationless state in a population” with a discussion of birds with two different colored wings. (p. 156)
The blending of traits could only possibly result in variations of the two colors; it could not produce a third color that was not a combination of the two colors that already existed.
This is the same problem that Eldridge and Gould experienced in trying to overcome the nonexistence of fossils in the record to explain the Precambrian mini explosion and the later Cambrian explosion. Neo-Darwinism has been born out of these dilemmas. Scientists has to start looking in a different direction for answers. Genes are the place they began looking.
Genes, of course, are the words, pages and books in the Library of Congress of life. the same problem exists with genes.
It turns out, though, that similar problems exists with genes. For simpler organisms to become more complex organisms, new information is necessary. Any theory that postulates the recycling of existing information is simply begging the question that needs to be answered: how does the new information arise that leads to evolutionary change?
Herman Muller’s experimentation with X-rays and resulting mutations gave rise to Neo-Darwinian theory. The assumption ever since is that mutations are the “creative process” on which natural selection works to weed out the non-functional forms from the functional forms. The mutations provide the “new” information necessary on which natural selection works. So exciting was this new twist to Darwinian Theory that T. H. Huxley announced in a centennial address on the theory of evolution that “Darwinism has come of age…. We are no longer having to bother about establishing the fact of evolution.” (quoting at p. 159)
James Watson and Francis Crick drilled down from genes to DNA in the 1950’s, looking for the process by which evolutionary changes are made at the cellular, DNA level with great hope. For many reasons that Meyer elucidates in detail, the hope of finding plausible answers to explain the generation of “new information” in DNA that could explain the evolutionary process have dimmed substantially as negative probabilities have grown exponentially.
Part of the reason for this is suggested in the article above. The fundamental question that must be answered defies explanation: where did the matter or information come from in the first place that was reworked by mutation and natural selection to create new life forms? But there is more bad news that I will cover in the next blog in the series.