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June 17 - August 8, 2019
This revolution was launched by an unlikely but now immortalized pair of scientists, Francis Crick and James Watson.
the 1950s, when Watson and Crick first illuminated the chemical structure and information-bearing properties of DNA,
living things, as much as high-tech devices, depend upon digital information—information that, in the case of life, is stored in a four-character chemical code embedded within the twisting figure of a double helix.
building a living organism requires information, and building a fundamentally new form of life from a simpler form of life requires an immense amount of new information.
DNA contains information in digital form, with its four chemical subunits (called nucleotide bases) functioning like letters in a written language or symbols in a computer code.
The type of information present in living cells—that is, “specified” information in which the sequence of characters matters to the function of the sequence as a whole—has generated an acute mystery. No undirected physical or chemical process has demonstrated the capacity to produce specified information starting “from purely physical or chemical” precursors. For this reason, chemical evolutionary theories have failed to solve the mystery of the origin of first life—a claim that few mainstream evolutionary theorists now dispute.
the well-known impasse in origin-of-life studies;
we don’t know of a material cause that generates functioning digital code from physical or chemical precursors,
intelligent design provides the best explanation for the origin of the information necessary to produce the first life.
Thus, to refute my claim that no chemical evolutionary processes had demonstrated the power to explain the ultimate origin of information in the DNA (or RNA) necessary to produce life from simpler preexisting chemicals in the first place, many critics cited processes at work in already living organisms—in particular, the process of natural selection acting on random mutations in already existing sections of information-rich DNA. In other words, these critics cited an undirected process that acts on preexistent information-rich DNA to refute my argument about the failure of undirected material
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Natural selection assumes the existence of living organisms with a capacity to reproduce. Yet self-replication in all extant cells depends upon information-rich proteins and nucleic acids (DNA and RNA), and the origin of such information-rich molecules is precisely what origin-of-life research needs to explain.
as Nobel Prize–winning molecular biologist and origin-of-life researcher Christian de Duve explains, theories of prebiotic natural selection fail because they “need information which implies they have to presuppose what is to be explained in the first place.”
I have long been aware of strong reasons for doubting that mutation and selection can add enough new information of the right kind to account for large-scale, or “macroevolutionary,” innovations—the various information revolutions that have occurred after the origin of life.
Many evolutionary biologists now grudgingly acknowledge that no chemical evolutionary theory has offered an adequate explanation of the origin of life or the ultimate origin of the information necessary to produce it.
Since 1980, when Harvard paleontologist Stephen Jay Gould declared that neo-Darwinism “is effectively dead, despite its persistence as textbook orthodoxy,”7 the weight of critical opinion in biology has grown steadily with each passing year.
A steady stream of technical articles and books have cast new doubt on the creative power of the mutation and selection mechanism.
group of scientists known as the “Altenberg 16,” are openly calling for a new theory of evolution because they doubt the creative power of the mutation and natural selection mechanism.10
As a host of distinguished biologists have explained in recent technical papers, small-scale, or “microevolutionary,” change cannot be extrapolated to explain large-scale, or “macroevolutionary,” innovation.11 For the most part, microevolutionary changes (such as variation in color or shape) merely utilize or express existing genetic information, while the macroevolutionary change necessary to assemble new organs or whole body plans requires the creation of entirely new information.
natural selection explains “only the survival of the fittest, not the arrival of the fittest.”
The technical literature in biology is now replete with world-class biologists13 routinely expressing doubts about various aspects of neo-Darwinian theory, and especially about its central tenet, namely, the alleged creative power of the natural selection and mutation mechanism.
Nevertheless, popular defenses of the theory continue apace, rarely if ever acknowledging the growing body of critical scientific opinion about the standing of the theory. Rarely has there been such a great disparity between the popular perception of a theory and its actual standing in the relevant peer-reviewed scientific literature. Today modern neo-Darwinism seems to enjoy almost universal acclaim among science journalists and bloggers, biology textbook writers, and other popular spokespersons for science as the great unifying theory of all biology. High-school and college textbooks present
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The extent of the disparity between popular representations of the status of the theory and its actual status, as indicated in the peer-reviewed technical journals, came home to me with particular poignancy as I was preparing to testify before the Texas State Board of Education in 2009. At the time the board was considering the adoption of a provision in its science education standards that would encourage teachers to inform students of both the strengths and weaknesses of scientific theories. This provision had become a political hot potato after several groups asserted that “teaching
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Yet today’s public defenders of a Darwin-only science curriculum apparently do not want these, or any other scientific doubts about contemporary Darwinian theory, reported to students. This book addresses Darwin’s most significant doubt and what has become of it. It examines an event during a remote period of geological history in which numerous animal forms appear to have arisen suddenly and without evolutionary precursors in the fossil record, a mysterious event commonly referred to as the “Cambrian explosion.” As he acknowledged in the Origin, Darwin viewed this event as a troubling
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Darwin’s Origin explained many classes of biological evidence with just two central organizing ideas. The twin pillars of his theory were the ideas of universal common ancestry and natural selection.
In a famous passage at the end of the Origin, Darwin argued that “all the organic beings which have ever lived on this earth have descended from some one primordial form.”1 Darwin thought that this primordial form gradually developed into new forms of life, which in turn gradually developed into other forms of life, eventually producing, after many millions of generations, all the complex life we see in the present.
Biologists often call Darwin’s theory of the history of life “universal common descent” to indicate that every organism on earth arose from a single common ancestor by a process of “descent with modification.”
The second pillar of Darwin’s theory affirmed the creative power of a process he called natural selection, a process that acted on random variations in the traits or features of organisms and their offspring.2 Whereas the theory of universal common descent postulated a pattern (the branching tree) to represent the history of life, Darwin’s idea of natural selection referred to a process that he said could generate the change implied by his branching tree of life.
Darwin was puzzled by a pattern in the fossil record that seemed to document the geologically sudden appearance of animal life in a remote period of geologic history, a period that at first was commonly called the Silurian, but later came to be known as the Cambrian. During this geological period, many new and anatomically sophisticated creatures appeared suddenly in the sedimentary layers of the geologic column without any evidence of simpler ancestral forms in the earlier layers below, in an event that paleontologists today call the Cambrian explosion. Darwin frankly described his concerns
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Agassiz concluded that the fossil record, particularly the record of the explosion of Cambrian animal life, posed an insuperable difficulty for Darwin’s theory.
consider brachiopods and trilobites, two of the best-documented creatures in the Cambrian fossil record by 1859.
The brachiopod exhibits a highly complex overall body plan, with many individually complex and functionally integrated anatomical systems and parts.
Even more sophisticated was the trilobite (see Fig. 1.4), with its three longitudinal lobes across its head (a raised middle lobe and a flatter pleural lobe to either side) and a body divided into three parts—head, chest, and tail, the former two consisting of as many as thirty segments. It had a pair of legs for every pleural groove and another three pairs for the head. Most dramatic of all were the compound eyes found on even some of the very early trilobites—eyes that afforded these not so primitive animals a 360-degree field of vision.
According to Darwin, variations in traits arise randomly.
Darwin conceded that the beneficial variations responsible for permanent change in species are both rare and necessarily modest. Major variations in forms, what later evolutionary biologists would term “macromutations,” inevitably produce deformity and death. Only minor variations meet the test of viability and heritability.
Darwin’s mechanism of natural selection and random variation necessarily required a lot of time to generate wholly novel organisms, creating a dilemma that Agassiz was keen to expose.
Agassiz explained his reasons for doubting the creative power of natural selection. Small-scale variations, he argued, had never produced a “specific difference” (i.e., a difference in species). Meanwhile, large-scale variations, whether achieved gradually or suddenly, inevitably resulted in sterility or death. As he put it, “It is a matter of fact that extreme variations finally degenerate or become sterile; like monstrosities they die out.”
Thus, Darwin realized that building, for instance, a trilobite from single-celled organisms by natural selection operating on small, step-by-step variations would require countless transitional forms and failed biological experiments over vast stretches of geologic time.
Darwin had very specific expectations for what paleontologists would find below the lowest known strata of animal fossils—in particular, “intervening strata showing fossils of increasing complexity until finally trilobites appeared.”
indeed, the kinds of variations that Darwin actually observed and described in developing his analogy between natural and artificial selection were in every case minor.
At the end of the day, as Agassiz hastened to note, the pigeons Darwin cited in support of the creative power of artificial and, by analogy, natural selection were still pigeons. More significant changes to the form and anatomical structure of organisms would, by the logic of Darwin’s mechanism, require untold millions of years, precisely what seemed unavailable in the case of the Cambrian explosion.
If Darwin is right, Agassiz argued, then we should find not just one or a few missing links, but innumerable links shading almost imperceptibly from alleged ancestors to presumed descendants. Geologists, however, had found no such myriad of transitional forms leading to the Cambrian fauna.
Of these earlier forms, Agassiz asked, “Where are their fossilized remains?” He insisted that Darwin’s picture of the history of life “contradict[ed] what the animal forms buried in the rocky strata of our earth tell us of their own introduction and succession upon the surface of the globe. Let us therefore hear them;—for, after all, their testimony is that of the eye-witness and the actor in the scene.”12
leading naturalists thought the fossil evidence presented a significant obstacle to Darwin’s theory. At the time, perhaps the best place to investigate the lowest known strata of fossils was Wales, and one of its leading experts was Roderick Impey Murchison, who named the earliest geologic period the Silurian after an ancient Welsh tribe. Five years before On the Origin of Species, he called attention to the sudden appearance of complex designs like the compound eyes of the first trilobites, creatures already thriving at the apparent dawn of animal life. For him, this discovery ruled out the
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The other pioneering explorer of Wales’s rich fossil record, Adam Sedgwick, also thought that Darwin had leaped beyond the evidence, as he told him in a letter in the fall of 1859: “You have deserted—after a start in that tram-road of all solid physical truth—the true method of induction.”
It was these strata that Sedgwick named after a Latinized English term for the country of Wales—“Cambria,” a designation that eventually replaced “Silurian” as the name for the earliest strata of animal fossils. Sedgwick emphasized that these Cambrian animal fossils appeared to pop out of nowhere into the geological column.
so dissimilar are the fossil types among different major periods and so sharp and sudden the break between them, that geologists could use this as one method for determining the relative age of strata.
this approach has become a standard dating technique,
it’s difficult to overemphasize how central the approach is to modern historical geology.
The history of life is not a continuum of development, but a record punctuated by brief, sometimes geologically instantaneous, episodes of mass extinction and subsequent diversification.”21 The question that Darwin’s early critics posed was this: How could he reconcile his theory of gradual evolution with a fossil record so discontinuous that it had given rise to the names of the major distinct periods of geological time, particularly when the first animal forms seemed to spring into existence during the Cambrian as if from nowhere?
Of course, Darwin was well aware of these problems. As he noted in the Origin, “The abrupt manner in which whole groups of species suddenly appear in certain formations has been urged by several paleontologists—for instance, by Agassiz, Pictet, and Sedgwick—as a fatal objection to the belief in the transmutation of species. If numerous species, belonging to the same genera or families, have really started into life all at once, the fact would be fatal to the theory of descent with slow modification through natural selection.”22
