Chapter X - On the Imperfection of the Geological Record
A big problem with Darwin's general theory of the gradual evolution of all organisms from a common ancestor was and remains the absence of innumerable transitional links in the fossil record. Darwin suggested several possible reasons for this absence of transitional links. He suggested that the:
...innumerable transitional links... existing in lesser numbers than the forms which they connect will generally be beaten out and exterminated during the course of further modification... (Page 293).
Thus, the first reason the "innumerable transitional links" failed to show up in the geological record was because there were relatively fewer of these species/varieties than there were of the species they evolved into or evolved from. Secondly, the geological record was too incomplete to support Darwin's general theory.
Darwin noted that we cannot expect to find transitional links between coexisting, related species. For example, when we look at two related forms such as the horse and the tapir, we should not expect to find transitional links between them. Rather, transitional forms remain in the geological record that point to a common ancestor of both the horse and the tapir. The same is true for the fantail and the pouter pigeon, both of which were bred from the common rock pigeon. There are not transitional links between the fantail and the pouter pigeons but there are transitional forms between each and the rock pigeon.
In the case of the rock pigeon and the fantail and pouter pigeon, the original form and the two descended forms coexist. Thus, Darwin believed: "It is just possible by the theory, that one of two living forms might have descended from the other..." (Page 294). He further noted that in such a case, the parent species would have remained unchanged for a long period of time while:
...It's descendants had undergone a vast amount of change; and the principle of competition between organism and organism, between child and parent, will render this a very rare event; because in all cases the new and improved forms of life tend to supplant the old and unimproved forms (page 295).
He concluded that "the number of intermediate and transitional links, between all living and extinct species, must have been inconceivably great" (Page 295).
Critique
According to Darwin's model of gradual evolution, a variety or intermediate form of a species acquired a favorable character that enabled it to replace the parent species across the parent species' range. Thus, the new variety or intermediate form spread out across the parent species' range and replaced the inferior members that constituted the parent form. However, Darwin needed to incorporate into his gradualist model some explanation for the absence of those innumerable intermediate forms in the fossil record. He decided to point out that the fossil record was incomplete and/or stochastic events; e.g., drought, predation, and disease had eliminated the "thousands" or even "a million" intermediate forms. The stochastic events were able to eliminate the intermediate forms because 1) those forms were relatively few in number though they had replaced the inferior parent population across its range and 2) they were localized though they had replaced the parent population across its range, and 3) though the intermediate forms were superior to and therefore replaced the parent forms, which appeared in the fossil record, they themselves, because they were not superior enough, did not persist long enough to appear in the same strata. Thus Darwin reconciled his vision of gradualism with the absence from the fossil record of the thousands and millions of intermediates. Those recalcitrant stratigraphic data!
Insofar as the completeness of the fossil record is concerned, Denton (1986:160) stated:
Since Darwin's time the search for missing links in the fossil record has continued on an ever-increasing scale. So vast has been the expansion of paleontological activity over the past one hundred years that probably 99.9% of all paleontological work has been carried out since 1860.
Stanley (1979:39) concluded:
The known fossil record fails to document a single example of phyletic (gradual) evolution accomplishing a major morphologic transition and hence offers no evidence that the gradualist model can be valid.
Because the rock pigeon coexists with the domestic fantail and pouter pigeon, Darwin conceded that rarely, the parent form and evolved forms coexist. Such a situation represented a "very rare event" because it conflicted with the gradualist model of superior transitional forms replacing the parental population through competition. Note also that, according to the fossil record, Homo erectus coexisted with its progenitor genus Australopithecus and all its offspring species, including H. sapiens. Not Darwinian.
Today, neo-Darwinists continue to line up co-existing species and genera and designate one as directly parental to the other. Thus they ignore Darwin's insistence upon the gradual evolution of a population into a new species and replacement of the parental species by the improved descendent species. That is, they deny one of the basic tenets of Darwinian evolution. Oddly, as was his usual practice, Darwin refrained from labeling the fantail and the pouter variety of pigeon as "primitive" or "advanced" in order to provide evidence for gradual evolution at work.
On the Lapse of Time, as Inferred from the Rate of Deposition and Extent of Denudation
Some of Darwin's opponents suggested to him that the earth had not existed long enough to accommodate the slow development of innumerable connecting links between the species. Darwin retorted that the earth was old. He referred to Sir Charles Lyell's work presented in Principles of Geology (1830-1833). Darwin described weathering by wind and water of rocks and of the slow deposition of materials to produce sedimentary layers hundreds of feet thick. The remarkable thickness of some of these layers illustrated the immense age of the earth. He further mentioned the slow erosion of hard cliff faces by the action of waves:
It is good to wander along the coast, when formed of moderately hard rocks, and mark the process of degradation. The tides in most cases reach the cliffs only for a short time twice a day, and the waves eat into them only when they are charged with sand or pebbles; for there is good evidence that pure water effects nothing in wearing away rock (page 298).
Darwin noted the rounded boulders at the bases of retreating cliffs, "showing how little they are abraded and how seldom they are rolled about!" (Page 298). It obviously took a long time to make a rock round when it rolled around only twice a day with the tide.
Darwin mentioned the slow process of weathering, erosion, and deposition producing such geological features as escarpments, eroded volcanic islands, uplifts at faults, and sedimentary strata. He cited the work of a "Professor Ramsay" who had collected "actual measurements in most cases" (Page 297) of a mass of conglomerate rocks comprising the surface of different parts of Great Britain. Professor Ramsay had determined that the Paleozoic strata were 57,154 feet thick, the secondary strata, 13,190 feet, and the Tertiary strata, 2,240 feet thick. The total 72,584 feet, Darwin calculated, was "very nearly thirteen and three-quarters British miles" (Page 298). Trying to grasp the amount of time required to produce sedimentary rocks 13 British miles thick:
...impresses the mind almost in the same manner as does the vain endeavour to grapple with the idea of eternity (Page 298).
In addition, a "Mr. Croll" had calculated that it would take certain rivers six million years to reduce the average elevation of "their areas of drainage" by 1,000 feet. Darwin further quoted Mr. Croll to illustrate the quantity of a million years:
...take a narrow strip of paper, 83 feet 4 inches in length, and stretch it along the wall of a large hall; then mark off at one end the tenth of an inch. This tenth of an inch will represent one hundred years, and the entire strip a million years (Page 298).
To illustrate how species could possibly change over long periods of time, Darwin pointed out that some breeders of "higher animals" had produced "sub-breeds" in the relatively short period of a hundred years. However:
It is not to be supposed that species in a state of nature ever change so quickly as domestic animals u
nder the guidance of methodical selection (Page 299).
Wild species change slowly because so few individuals within the population in the same area possess the same favorable modification, and, the modification has little effect because the existing species is well adapted to its living situation. Darwin concluded:
...we have no means of determining, according to the standards of years, how long a period it takes to modify a species... (Page 299).
Critique
According to Charles Lyell, geological processes such as weathering, erosion, and deposition operate at the same rates now as they did in the past. This assumption was labeled "uniformitarianism". Of course, some geological processes cause rapid change; e.g., flooding, volcanism, seismic events, and asteroid impacts. The assumption that Lyell's assumption of uniformitarianism for geological processes also applied to the rates of radioactive decay was obviously an assumption that may but may not be correct. If the rates of radioactive decay vary (see essay above: Mutable Rates of Radioactive Decay), then our data that indicate the earth to be about four and half billion years old are likewise incorrect.
How did Professor Ramsay in the mid-1800s measure the Paleozoic strata to be 57,154 feet (10.8 miles) thick?
To illustrate how species change over long periods of time, Darwin pointed out that domestic species can change into "sub-breeds" in a short period of time, a hundred years. This observation created problems because Darwin did not recognize differences between variation within the limits of a class (a domestic species) and the macroevolutionary change of species into new classes of organisms. He noted that domestic species changed rapidly but rapid change suggested the interference of selection and planning by mind, in the case of domestic species, by the super- or unnatural selection of man's mind. Insofar as wild species were concerned, however, the appearance of new species had to occur ever so slowly by natural selection acting on chance events and/or Lamarckian changes in the species. Rapid speciation in the wild was therefore not acceptable because it implied interference by mind. Darwin concluded that rapid changes in species did not happen in the wild because 1) so few individuals are produced that possess the favorable character and 2) the species is so well adapted already to existing conditions that the favorable character provides little benefit. Thus, he held tenaciously to his concept of gradual evolution whereby the population as a whole through minuscule steps changes into a new species over vast amounts of time, replacing/displacing the inferior parent species. In regard to rapid speciation, Darwin noted: "To admit all this is, as it seems to me, to enter into the realms of miracle..." (Page 232).
Let's see...domestic species change rapidly because mind guides the selection process and wild species change ever so slowly because minute changes have such a small influence on the population, and because mind is not or cannot influence the creative process. Darwin referred to the domestication process by mind as "the guidance of methodical selection" (Page 299).
One wonders what Darwin would have thought of current paleontological records that show the general pattern of the abrupt appearance and disappearance of species and higher classes of organisms? What did he think of the "Cambrian explosion"? Wells (2000:35) noted:
But the Cambrian fossil pattern didn't fit Darwin's theory. Instead of starting with one or a few species that diverged gradually over millions of years into families, then orders, then classes, then phyla, the Cambrian starts with the abrupt appearance of many full-formed phyla and classes of animals. In other words, the highest levels of the biological hierarchy appeared right at the start.
Darwin floundered over the Cambrian problem: "several of the main divisions of the animal kingdom suddenly appear in the lowest known fossiliferous rocks" and he called this observation a "serious" problem which:
...at present must remain inexplicable; and may be truly urged as a valid argument against the views here entertained.
Wells said "many" fully-formed phyla and classes of animals appeared suddenly in the Cambrian while Darwin described the number of those sudden appearances as "several". The fact is that of 18 phyla of living animals, 2 appeared late in the Precambrian and 12 appeared abruptly and fully formed in the Cambrian with no evidence of predecessors (Wells, 2000:37-41).
One wonders what Darwin would have thought of the production of 300+ endemic species of cichlid fishes in Lake Victoria, Africa since the lake was dry 12,400 carbon-14 years ago. What would he have thought of the stratigraphic evidence of nearly all the orders of Mammalia, from flying bats and swimming dolphins to climbing primates, in a period of about 10 million years, the species life-times of 3 - 4 mammalian species, during the Paleocene and early Eocene? Likely, he would have reasoned that natural selection was more powerful and rapid than he first thought and that speciation without isolation was a matter of gradual evolution at lightning speed? His model of the gradual evolution of species was operative always... except when it repeatedly was not.
On the Poorness of Paleontological Collections
The fossil record is poor for a number of reasons:
(1) Paleontologists commonly described species based on the finding of a single and often broken bone.
(2) Bones and other evidences often come from a single collection spot.
(3) Collectors had surveyed a small part of the earth's surface.
(4) No organism without hardened body parts was preserved.
(5) Shells and bones on the bottom of the ocean decay and disappear because of the lack of deposition of sediments. Darwin observed that "the bright blue tint of the water bespeaks its purity" (Page 299), which meant to him that the waters of the oceans were largely free of materials for deposition.
(6) When sedimentary beds with fossils were raised and exposed above sea level, "rainwater charged with carbonic acid... dissolved them..." (Page 300).
(7) "Lastly, many great deposits requiring a vast length of time for their accumulation, are entirely destitute of organic remains, without our being able to assign any reason..." (Page 300).
In his usual rambling and unorganized fashion, Darwin continued to explain beyond "lastly" the main reasons for imperfection in the fossil record. He believed the lines between geological formations represented vast amounts of time:
The frequent and great changes in mineralogical composition of consecutive formations, generally implying great changes in the geography of the surrounding lands, whence the sediment was derived, accord with the belief of vast intervals of time having elapsed between each formation (Page 301).
Darwin failed to explain the relationship between the paucity of the fossil record and his belief that the absence of deposition between formations represented great expanses of time. Apparently, he thought his conclusions too obvious to need explanation. Perhaps he thought that if there were great expanses of time and no depositions during those times, there were no fossils; all the evidence had weathered and eroded away. The evidence of all those intermediate life forms was forever hidden in the lines of non-information that divided the rock formations. The oddly synchronized fossilization of the millions of intermediate forms with the denudations represented by the lines dividing the rock strata was a remarkable if unfortunate coincidence.
At this point, Darwin interjected another reason for a lack of marine fossils in the record. He reasoned that wave action destroyed those fossils formed along the coastline. He subsequently reasoned that fossils in the shallow oceans could only persist across thick supplementary layers if the substrate was sinking. If the substrate rose, carbonic acid in rainwater would erase them. Then he recanted:
These remarks apply chiefly to littoral and sub-littoral deposits. In the case of an extensive and shallow sea, such as that within a large part of the Malay Archipelago, where the depth varies from 30 or 40 to 60 fathoms, a widely extended formation might be formed during a period of elevation, and yet not suffer excessively from denudation during its slow upheaval... (Page 302).
That weathering and erosion (Darwin's "denudat
ion") had occurred over wide areas, was evident. The presence of magmatic and metamorphic rocks, which had formed deep within the earth's crust, across wide areas of the earth's surface was evidence of denudation of the overlying rock layers. The weathering and erosion of those vast areas accounted for the disappearance of much of the fossil record.
In conjunction with land upheavals, subsidence, and denudation, new species will form to take advantage of "new situations" (Page 304). Notwithstanding the constant changes of the earth's surface and the creation of new species better adapted to new environments, the fossil record insofar as mammalian remains were concerned, was depauperate because such remains were "accidental and rare" (Page 300).
Critique
It is still, as it was in Darwin's day, overwhelmingly true that the first representatives of all the major classes of organisms known to biology are already highly characteristic of their class when they make their initial appearance in the fossil record (Denton, 1986:162).
Furthermore, as stated above, vertebrate species appear and disappear abruptly and, aside from microevolutionary changes in size, do not change their bone structure over the life of the species. That is, natural selection shows no power to change the morphology of established species.
Though most scientists agree that the average longevity of a mammal species is 3 to 4 million years (Tattersall (2014:56), Prothero and Heaton (1996), in their fossil studies in South Dakota, found that the species life of artiodactyl ungulate species was some 1.5 to 2 million years.
Notable in the study of the White River fauna in the South Dakota Bad Lands by Prothero and Heaton was a drop in mean temperature of 11 degrees C during the Orellan. Despite the dramatic changes in climate and vegetation, the species showed amazing evolutionary stability.
Insofar as the completeness of the fossil record is concerned, as stated above, Denton (1986:160) noted that 99.9% of all fossil evidence has been discovered since 1860. Darwin's innumerable intermediates have remained hidden in absentia within those lines (a line has no dimension) of no-data between the geologic strata. It seemed rather subversive of that infinitude of intermediate forms to establish themselves only on those parts of the earth where weathering and erosion would erase all evidence of their existence, where either fortuitously or unfortunately, the intermediates were forever fallen into the cracks?
Of interest, the arrangements of many geologic strata register deposition tied to catastrophic events; e.g., floods, volcanic and seismic activity, and asteroid impacts.
On the Absence of Numerous Intermediate Varieties in Any Single Formation
Darwin derived a number of speculations to explain why evidence of the numerous intermediate gradations between species failed to appear within any single rock stratum. He failed to specifically organize his thoughts; summarily, I attempted to do that by concept:
1) The rock formations required less time to develop than the species required to change.
2) Species that appeared abruptly in a rock formation did so because they moved to that place from another location.
3) The abrupt disappearance of a species from a rock formation showed that environmental conditions changed and the species had moved out of the area.
4) Different species in the ocean are unevenly distributed and therefore different rock formations demonstrate the varied distributions.
5) Species fossils are absent from formations because when those formations rose above sea level, weathering and erosion destroyed the fossils.
6) Darwin said that some geologists thought some rock formations were older than some species because the species moved into and out of locations, leaving no evidence of numerous intermediate steps. A species would leave an area, undergo modification, and then return and be classified as a different species.
7) Darwin complained "that naturalists have no golden rule by which to distinguish species and varieties..." and "It is notorious on what excessively slight differences many paleontologists have founded their species..." (Page 307). Darwin believed that different "species" instead of intermediate graduations between species appeared in the fossil record because scientists were unable to tell the differences between species and intermediates. To further make his point, he noted that taxonomists often classified the fossil remains of living species as different species when there was "no differences whatever" between them (Page 308).
8) For species widely distributed and those "that propagate rapidly and do not wander much" (Page 308), speciation occurred in localized areas. Local transformations/varieties/gradations "do not spread widely and supplant their parent-forms until they have been modified and perfected in some considerable degree" (Page 308). Thus, with all the intermediate gradations confined to small geographical areas, the probability of finding them in the fossil record is small.
9) Evolution of a species requires a long period of time, however, the parent species may go unchanged for a longer period of time. Thus, there are a lot more formations with the unchanged parent species than there are with the fossils of intermediate forms.
10) The fossil record is not complete enough to reveal intermediate connections between related species. The incompleteness of the fossil record explains, for example, our inability to identify the parent species for domestic plants and animals. Darwin concluded: "What geological research has not revealed, is the former existence of infinitely numerous gradations, as fine as existing varieties, connecting together nearly all existing and extinct species" (Page 309).
Critique
In this critique, I will discuss an apparent contradiction of Darwin's views on the amount of time required for speciation versus strata formation, Gould and Eldridge's evolutionary model "punctuated equilibrium," Darwin's rebuttal of the coexistence of parent and offspring species, and fossil evidence of four-legged animals on land coexisting with or before their boney fish "ancestors". This seemed to be the best approach to adequately critique Darwin's speculations about why the myriad of intermediate forms failed to appear in the fossil record. Basically, the fossil record does not contain evidence of numerous intermediates because organisms do not evolve gradually; that is, there is no evidence of numerous intermediates because they never existed.
From Item 1 above, we note that evidence for speciation is absent in the rock formations because the strata developed faster than species evolved into new species. On the other hand, Darwin said that:
... Bronn and Woodward, have concluded that the average duration of each formation is twice or thrice as long as the average duration of specific forms (Page 305).
I smell a contradiction? From Phil Johnson (1993:50):
The fossil record was revisited in the 1970s in works by Stephen Jay Gould, Niles Eldredge, and Steven Stanley. Gould and Eldredge proposed a new theory they called "punctuated equilibrium" ('punk eek' to the irreverent), to deal with the embarrassing fact: the fossil record today on the whole looks very much as it did in 1859, despite the fact that an enormous amount of fossil hunting has gone on in the intervening years. In the words of Gould:
1) Stasis. "Most species exhibit no directional change during their tenure on earth. They appear in the fossil record looking pretty much the same as when they disappear; morphological change is usually limited and directionless."
2) Sudden appearance. "In any local area, a species does not arise gradually by the steady transformation of its ancestors; it appears all at once and 'fully formed.'"
Notwithstanding the fossil evidence, neo-Darwinists continue to designate sister species and genera, coexisting, as "advanced" species and genera and others as "primitive" ancestors in evolutionary lines of ascent. For example, Homo erectus coexisted with its founder genus Australopithecus and with all of its offspring species, including Neanderthal man (Homo sapiens neanderthalensis) and modern man (Homo sapiens sapiens). How did H. erectus evolve into H. neanderthalensis and into H. sapiens in a Darwinian fashion and coexist with them? Without saltation events, where are the innumerable tiny gradat
ions between coexisting parental and offspring stock, one evolving into the other? How is it that the parent species, isolated from its offspring species, failed to continue to evolve? In the Darwinian model, a species population gradually evolved into a new species with improved offspring competing with and replacing progenitors. Isolation could produce coexisting and related forms, but these would not line up as ancestor and successor species but as sister species pointing back to some unknown, ancestral archetype. Darwin (Pages 294-295) noted:
It is just possible by the theory, that one of two living forms might have descended from the other for instance, a horse from a tapir; and in this case direct intermediate links will have existed between them. But such a case would imply that one form had remained for a very long period unaltered, whilst its descendants had undergone a vast amount of change; and the principle of competition between organism and organism, between child and parent, will render this a very rare event; for in all cases the new and improved forms of life tend (weasel-word) to supplant the old and unimproved forms (emphasis, mine).
In the case of human evolution, we have an obvious problem with the inability of random mutation to have created modern chimpanzees and our own species from a common ancestor over a span of 6 million to 10 million years. Studies of mutation rates in the war between the malaria parasite and humans has provided some insights into the limits of random mutation. Behe (2014:60-61) observed:
...The likelihood that Homo sapiens achieved any single mutation of the kind required for malaria to become resistant to chloroqine - not the easiest mutation, to be sure, but still only a shift of two amino acids - the likelihood that such a mutation could arise just once in the entire course of the human lineage in the past ten million years, is minuscule - of the same order as, say, the likelihood of you personally winning the Powerball lottery by buying a single ticket.
On average, for humans to achieve a mutation like this by chance, we would need to wait a hundred million times ten million years. Since that is many times the age of the universe, it's reasonable to conclude the following: No mutation that is of the same complexity as chloroquine resistance in malaria arose by Darwinian evolution in the line leading to humans in the past ten million years.
Had Darwin been alive today and apprised of our more complete fossil record and the numerical limits of gene mutation (natural variation), would he have attempted to compile some form of On the Origin of Species? For example, how would he have white-washed a finding reported under Verbatim by Time magazine, January 12, 2010? This note stated:
"It blows the whole story out of the water"... Jenny Clack, a paleontologist at Cambridge University in England, on a set of fossilized footprints found in Poland that show four-legged animals on land nearly 400 million years ago, well before the date scientists had given for animals' emergence from the sea...
I think it clever of those land dwelling quadrupeds to have evolved in a Darwinian gradualist fashion in concert with or even before the first appearance of their bony fish ancestors.
On the Sudden Appearance of Whole Groups of Allied Species
Darwin observed:
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" (Page 311).
In an attempt to save his theory from that "fatal objection," Darwin restated that the fossil record was inadequate; the world was large and the areas sampled small. Furthermore, the intervals of time as represented by the cracks of no data between rock formations were likely immense and "... longer perhaps in many cases than the time required for the accumulation of each formation" (Page 312).
Darwin further suggested that the transitional forms likely developed in a localized area and then spread rapidly to displace the parent species. Once the fortuitous adaptation had developed:
...a comparatively short time would be necessary to produce many divergent forms, which would spread rapidly and widely, throughout the world (Page 312).
Thus, the new species would only appear to have appeared abruptly in the fossil record.
A "Professor Pictet" had reviewed Darwin's work and told him that he could not see how transitional gradations had received any advantage from rudimentary forms of the bird's wing. Darwin countered that the penguin makes good use of its "wings". He also imagined that over time the penguin could develop the ability to fly by first flapping its wings at the water's surface and then gliding would evolve.
Darwin then noted several new discoveries that illustrated how paltry the fossil record was in the mid-1800s. He said that recent fossil findings had required Professor Pictet to alter his "great work on Paleontology" (Page 312). In addition:
Cuvier used to urge that no monkey occurred in any tertiary stratum; but now extinct species have been discovered in India, South America, and in Europe, as far back as the Miocene stage (Page 313).
Darwin also noted that the discovery of the fossilized Archaeopteryx, with a long lizard-like tail bearing a pair of feathers on each joint, and with its wings furnished with two free claws shows "how little we as yet know of the former inhabitants of the world" (Page 313).
He discussed the distribution of sessile cirripedes and teleost (modern fish) in the fossil record. A fossilized cirripedes was a member of a common extant genus as were the teleost fishes, fossils of which dated back to the Jurassic and Triassic. His point was that there existed predecessors to groups of species that paleontologists first thought appeared abruptly in the rock strata. Few but ancient specimens showed that the species modified locally and then spread widely rapidly and subsequently made their "abrupt" appearances in the rock strata.
Critique
Of interest, Darwin believed the lines, which by definition have no breadth, between rock strata provided evidence for the lack of fossils and for the immense periods of time that he imagined existed between the deposition of rock formations. "Evidence" derived from the absence of information provided by nothing existing between the rock formations could be considered at best - speculative. Only repetition can re-reply to Darwin's redundancy.
And, what was Darwin thinking in his speculation that species would evolve favorable characters within a localized area; within a species population and then would in a "short time...produce many divergent forms that would spread widely" (Page 312). Perhaps he had forgotten his earlier statement under Illustrations of the Action of Natural Selection, or the Survival of the Fittest:
If the new variety were successful in its battle for life, it would slowly spread from a central district, competing with and conquering the unchanged individuals on the margins of an ever increasing circle (Page 99).
Thus, Darwinian gradualism was fast and/or slow, depending upon the needs of the metaphysical, materialist script. Unfortunately, the production of many divergent forms in a "short time" did not support his vision of the gradual evolution of "innumerable gradations:"
We have seen in the last chapter that whole groups of species sometimes falsely appear to have been abruptly developed; and I have attempted to give an explanation of this fact, which if true would be fatal to my views (Page 323).
Thus, Darwin's concession of the production of many forms in a short period of time was fatal to his "views" on the gradual evolution of all species from a common ancestor. Salvaging gradualism was quite a chore, given the add-on idea of isolation without isolation, gradualism in a hurry to address the absence of intermediates, and the abrupt appearance of allied and unallied species groups in the rock strata; e.g. the Cambrian explosion.
Next, Darwin abandoned the subject; understandably, of the abrupt appearance of whole groups of allied species in rock formations. He talked about how birds might have developed wings and the ability to fly through small slow changes. Why he changed the subject was not clear.
Insofar as the incompleteness of the fossil record is concerned, I d
efer to Michael Denton (1986:160-161):
Since Darwin's time the search for missing links in the fossil record has continued on an ever-increasing scale. So vast has been the expansion of paleontological activity over the past one hundred years that probably 99.9% of all paleontological work has been carried out since 1860. Only a small fraction of the hundred thousand or so fossil species known today were known to Darwin. But virtually all the new fossil species discovered since Darwin's time have either been closely related to known forms or, like the Poganophoras, strange unique types of unknown affinity.
On the Sudden Appearance of Groups of Allied Species in the Lowest Known Fossiliferous Strata
Darwin recognized his nemesis:
that, though we find in our geological formations many links between the species which now exist and which formerly existed, we do not find infinitely numerous fine transitional forms closely joining them all together; - the sudden manner in which several groups of species first appear in our European formation; - the almost entire absence, as at present known, of formations rich in fossils beneath the Cambrian strata, - are all undoubtedly of the most serious nature (Page 318).
To the question why we do not find rich fossiliferous deposits belonging to these assumed earliest periods prior to the Cambrian system, I can give no satisfactory answer (Page 316).
Nevertheless, Darwin was willing to provide unsatisfactory conjectures that might explain the lack of fossil evidence prior to the Cambrian period and to explain the subsequent "Cambrian explosion" of animal phyla. To account for the absence of Precambrian fossils, he speculated that there were vast continents where oceans now exist and ancient oceans previously existed where land masses now occur. Thus, the Precambrian fossilized layers under the pressure of water "might have undergone far more metamorphic action than strata which have always remained nearer to the surface" (Page 318). That is, water pressure destroyed the Precambrian fossils.
On the absence of Precambrian fossils, Darwin further speculated:
...that the world at a very early period was subjected to more rapid and violent changes in its physical conditions than those now occurring; and such changes would have tended to induce changes at a corresponding rate (more rapid) in organisms which then existed (Page 316).
Darwin also recognized problems in the fossil record that pointed toward stasis and microevolution within distinct/established species:
Some of the most ancient animals, as the Nautilus, Lingula, etc., do not differ much from living species; and it cannot on our theory be supposed, that these old species were the progenitors of all the species belonging to the same groups which have subsequently appeared, for they are not in any degree intermediate in character (Page 315).
Critique
Darwin showed remarkable insight into the problems facing his general theory that all life forms evolved from a common ancestor:
1) The fossil record failed to show the innumerable intermediate life forms required to support the gradual evolution of species from ancestral forms.
2) The abrupt appearance of specialized life forms in the rock formations indicated that species did not develop gradually, a basic tenet of Darwin's model.
3) Fossil evidence showed that "predecessors" were either distinct, specialized forms or were species closely related to existing life forms and were therefore "sister species" equally distant from some hypothesized archetype.
A hundred, fifty years of additional paleontological investigations since 1860 solidified the non-Darwinian patterns of speciation noted above.
Of interest, Darwin speculated that prior to the Cambrian, the early earth experienced "rapid and violent changes in its physical conditions." Thus, organisms were forced to gradually evolve in a hurry to adapt to the rapidly changing conditions? What happened to Darwin's total commitment to Lyell's uniformitarian principles and the ever so gradual evolution of species? That is, 12 of the 18 major phyla of animals presently living developed abruptly to accommodate rapid changes in the landscape during the Precambrian and Cambrian Periods?
But at other times the rock formations, rather than species, developed too rapidly to accommodate the enormous amounts of time required for ancient life forms to evolve in the gradualist Darwinian fashion. Darwin had previously noted:
Although each formation may mark a very long lapse of years, each probably is short compared with the period requisite to change one species into another (page 304).
Thus, species groups and, alternatively, rock formations developed either rapidly or ever so slowly but always in a Darwinian fashion, depending upon the changing needs of the gradualist script to explain the absence of intermediates in the fossil record. Darwin hoped that if others would not believe that the water pressure of inundating oceans had erased the Precambrian evidence of gradualism, maybe colleagues would accept these additional attempts to explain away the abrupt appearance of 12 of 18 existing animal phyla during the Cambrian. By contrast, fossil evidence from the Precambrian strata fails to illustrate any linkage to the Cambrian.
Paleontologists have uncovered only four or five types of fossil forms in Precambrian strata; e.g., Dickinsonia, Spriggina, Charnia, Kimberella (a possible mollusk), and sponges. The first three are variously, speculatively thought to be lichens, protozoans, or possibly cnidarians (phylum that includes hydra, jellyfish, sea anemone, and coral). In order for Dickinsonia, Spriggina, Charnia, and Kimbrella to be ancestral to multiple Cambrian phyla, they would have to be undifferentiated and simple in structure. And thus they, relatively speaking, are. However, because of their relative simplicity, these Precambrian forms share no clear affinities to any Cambrian phyla. The Cambrian fauna included annelids (segmented worms), arthropods (insects, crustaceans, spiders etc.), Cambrian mollusks, echinoderms (starfish family), and chordates (four species of jawless fish) (Meyer 2013:74-75, 82-84). On the other hand, if any of the few Precambrian forms did evolve toward any particular Cambrian phylum, all of which are highly differentiated, they would have to evolve through multiple, distinct descendant lines in order to produce numerous complex organs and structures:
Heads, jointed limbs, compound eyes, guts, anuses, antennae, notochords, stereoms, lophophores (a tentacle feeding organ), and numerous other distinguishing characteristics of many different animals...(Meyer 2013:94).
The fact that the highly differentiated Cambrian phyla arrived without affinities to organisms from the late Precambrian shows that the production during the Cambrian of nearly all animal types (phyla) extant today was "explosive". Of course, the phylum Porifera (sponges) appeared abruptly in the Precambrian without evidence of predecessors and has continued to the present.