Over the life of this website, I have critiqued a number of Christadelphian anti-evolution lectures and articles. Without exception, all of them were characterised by errors of fact, logical fallacies, and a tendency to recycle long-refuted special creationist attacks on evolution. Having debunked a considerable number of these anti-evolution articles, and discovered that subsequent attacks on evolution merely recycled the same points refuted a thousand times, [1] I have opted not to publish any further critiques if only because there is little point in slapping a new title on an old refutation.
This doesn't mean that other Christadelphian evolutionary creationists have likewise stopped publishing critiques of bad anti-evolution articles. Recently, the author of the excellent The Fourth Conversation has written a detailed critique [2[ of an anti-evolution lecture by an Australian Christadelphian evolution denialist, ably pointing out its many errors. Given this, there is no point in duplicating his excellent refutation. However, I would like to expand on one point in order to highlight one of the fundamental problems blighting fundamentalist attacks on evolution, namely a failure to verify references. After all, if the sources on which you rely to make your argument are flawed, your argument is dead in the water.
Around halfway through his critique, Pearson writes
[18:40] The speaker quotes “Gliedman, 1982 p90-91” who says “No fossil or other physical evidence directly connects man to ape…”
Comment: I have been unable to find this book or reference on the web, and thus cannot really comment on the context of the quote. Furthermore, the book quoted was published in 1982, which was long before the genetic discoveries of recent years which have put the existence of a common ancestor between man and ape beyond dispute.
While Pearson has ably shot down this objection by pointing out both the fact anything dating from 1982 is hopelessly dated given the considerable advances made in molecular biology and palaeoanthropology, there is merit in trying to track down this reference to see if it is just another example of special creationist quote mining. It would not be the first time a Christadelphian evolution denialist failed to properly verify a reference.
After weaving some Google magic, I was able to come up with the reference. [3] The source was a short article in Science Digest, a now-defunct popular science magazine [4], while the author, John Gliedman, appeared to have been a psychologist and science writer. Far from being a review article in a high-impact journal written by a leading figure in palaeoanthropology or human genetics, it was a popular article in a popular magazine by a science writer whose area of expertise lay well outside the subject on which he was writing. This of course does not mean that articles written by science writers aiming to distill a complex subject to a form accessible to the layperson are always wrong. Far from it. However, given that the Christadelphian anti-evolutionist was attempting to show that evolution was false, that obliged him to go the extra mile to ensure that the references to which he appealed for support were authoritative.
When searching for the sentence "No fossil or other physical evidence directly connects man to ape…" I was hardly surprised to see that by far the overwhelming number of citations came from special creationist articles, which immediately raised a huge red flag. As a rule, when an article by a non-creationist is widely cited by fundamentalist Christians, you can practically guarantee that the quote from that article has been misunderstood or taken out of context. It also raises the question of whether the person citing the article has actually read the article in full, or is merely uncritically citing another creationist author who has cited the article.
One of the hits was from a 1992 author by the special creationist author Jerry Bergman, whose citation of Gliedman follows:
The assertion that the fossil record is incompatible with gradualism is likewise incorrect. Biologist Douglas Theobald notes that the fossil record is exactly what we would expect to see under a model of allopatric speciation, and therefore it does not need any 'miracle mutations' to explain it:
As one can see, Gliedman's assertions have not stood the test of time. What about his assertion that "no fossil or other physical evidence directly connects, man to ape"? His claim that no fossil evidence directly connects man to ape reflects a poor grasp of palaeontology. We do not expect to find direct ancestors in the fossil record. Rather, we aim to build relations between species. As Louise Mead points out:
The idea that modern man appeared suddenly is incorrect. The fossil record shows a clear trend towards obligate bipedality and increasing cranial capacity, the latter clearly demonstrated by a plot of cranial size versus time:
Evolutionary biologist Nick Matzke puts it perfectly when he states:
Irrespective of whether the Christadelphian evolution denialist who appealed to Gliedman read the Science Digest article in which the argument appeared, or discovered the quotation in another special creationist article, the fact that he failed to check a thirty-six year old article to see if Gliedman's assertion was backed by the evidence represents a major failure in fact-checking. James 3 reminds us that those who aspire to be teachers will be held to a higher standard given the importance of ensuring that what they teach is true. Monumental failures to adequately verify references such as this remind us of the importance of this apostolic principle.
References
1. This term has its own acronym - PRATT. After a while, it is easier to simply point people to a FAQ list given the failure of special creationists to recognise that their talking points were debunked ages ago.
After weaving some Google magic, I was able to come up with the reference. [3] The source was a short article in Science Digest, a now-defunct popular science magazine [4], while the author, John Gliedman, appeared to have been a psychologist and science writer. Far from being a review article in a high-impact journal written by a leading figure in palaeoanthropology or human genetics, it was a popular article in a popular magazine by a science writer whose area of expertise lay well outside the subject on which he was writing. This of course does not mean that articles written by science writers aiming to distill a complex subject to a form accessible to the layperson are always wrong. Far from it. However, given that the Christadelphian anti-evolutionist was attempting to show that evolution was false, that obliged him to go the extra mile to ensure that the references to which he appealed for support were authoritative.
The cover of the issue in which Gliedman's article appeared. No, these shapes won't activate either your left or right hemisphere...
When searching for the sentence "No fossil or other physical evidence directly connects man to ape…" I was hardly surprised to see that by far the overwhelming number of citations came from special creationist articles, which immediately raised a huge red flag. As a rule, when an article by a non-creationist is widely cited by fundamentalist Christians, you can practically guarantee that the quote from that article has been misunderstood or taken out of context. It also raises the question of whether the person citing the article has actually read the article in full, or is merely uncritically citing another creationist author who has cited the article.
One of the hits was from a 1992 author by the special creationist author Jerry Bergman, whose citation of Gliedman follows:
The fossil record does not support the case for natural selection. One excellent summary (Gliedman, 1982, p. 90-91) reflects the current opinion well:The context of Gliedman's article was the controversy over whether the pattern of evolution in the fossil record could be explained by gradual evolution, or required 'miracle mutations' to explain it. Evolution has unfortunately attracted more than its fair share of bad popular science writing, and Gliedman's article was no exception. Gliedman's comments on the Cambrian explosion and the alleged inability of 'gradualists' to explain the sudden changes in the fossil record have not stood the test of time. Christian palaeontologist Keith Miller, writing at BioLogos points out that the Cambrian explosion did not take place in a geological instant, with some phyla appearing before and after the base of the Cambrian:
No fossil or other physical evidence directly connects, man to ape…. The problem for gradualists [those who support gradual evolution or orthodox Darwinian evolution] is that . . . these ancestral species remain essentially unchanged throughout their million-year life spans, yet each of them differs substantially from its immediate predecessor. . . . Sudden-change theorists find plenty of support for their point of view in the glaring list of critical evolutionary events that no gradualist, including Darwin, has ever explained satisfactorily. In addition to the lack of a missing link to explain the relatively sudden appearance of modern man, gradualists cannot easily explain the mysterious ‘Cambrian explosion’ 600 million years ago. This was an evolutionary leap that transformed the earth . . . from a mess of simple microscopic bacteria and blue-green algae to a planet bursting at the seams with primitive representatives of every type of multicellular plant and invertebrate animal-from the lowly protozoans to such complex creatures as the trilobites, … the best that gradualists can do is point to the ground beneath their feet; the fossils buried in the earth somewhere, they say, and may someday be discovered. [5]
If the Cambrian explosion is understood to comprise the time from the base of the Cambrian to the Chengjiang fossil beds, then this period of diversification in animal body plans appears to have lasted about 20 million years. However, not all living animal phyla with a fossil record first appear within this time window. The colonial skeleton-bearing bryozoans, (click for image) for example, are not known from the fossil record until the end of the Cambrian around 491 million years ago.8 More significantly, several living invertebrate phyla have a fossil record that extends into the late Neoproterozoic before the Cambrian. Sponges (click for image) have been recognized as early as 580 million years, cnidarians (click for image--the group includes jellyfish and anemones) are present among the Ediacaran animals at around 555 million years, and the stem groups (see discussion below) for some other phyla were also likely part of the Ediacaran communities.
Defining the Cambrian “explosion” is not as straightforward as it might seem. Although there was clearly a major burst of evolutionary innovation and diversification in the first 20 million years or so of the Cambrian, this was preceded by an extended period of about 40 million years during which metazoans (multicellular animals) arose and attained critical levels of anatomical complexity. The Ediacaran saw the appearance of organisms with the fundamental features that would characterize the later Cambrian organisms (such as three tissue layers, and bilaterally symmetric bodies with a mouth and anus), as well as the first representatives of modern phyla. The base of the Cambrian is not marked by a sharp dramatic appearance of living phyla without Precambrian roots. It is a subjectively defined point in a continuum. The Cambrian “explosion” appears to have had a “long fuse.” [6]
As the timeline shows, the idea of an instantaneous appearance of complex life at the base of the Cambrian is incorrect. Source
The assertion that the fossil record is incompatible with gradualism is likewise incorrect. Biologist Douglas Theobald notes that the fossil record is exactly what we would expect to see under a model of allopatric speciation, and therefore it does not need any 'miracle mutations' to explain it:
Here I present quotes from The Origin of Species, Chapter 10, "On the imperfection of the geological record," that basically sum up the conclusions of PE:"When we see a species first appearing in the middle of any formation, it would be rash in the extreme to infer that it had not elsewhere previously existed. So again, when we find a species disappearing before the last layers have been deposited, it would be equally rash to suppose that it then became extinct. We forget how small the area of Europe is compared with the rest of the world ... when we see a species first appearing in any formation, the probability is that it only then first immigrated into that area." (p. 423)
"... varieties are generally at first local; and that such local varieties do not spread widely and supplant their parent-form until they have been modified and perfected in some considerable degree. According to this view, the chance of discovering in a formation in any one country all the early stages of transition between any two forms is small, for the successive changes are supposed to have been local or confined to some one spot." (pp. 427-428)
"... it might require a long succession of ages to adapt an organism to some new and peculiar line of life, for instance, to fly through the air; and consequently that the transitional forms would often long remain confined to some one region; but that, when this adaptation had once been effected, and a few species had thus acquired a great advantage over other organisms, a comparatively short time would be necessary to produce many divergent forms, which would spread rapidly and widely throughout the world." (p. 433)It is obvious from all of these quotes that Darwin did not think the "gaps" between fossil species were only due to geological processes, but that they are a direct consequence of natural speciation processes. Phyletic gradualism is a strawman when attributed to Darwin, and this is one of the reasons why so many evolutionary biologists reacted strongly to the initial presentation of the hypothesis of PE. Furthermore, it is erroneous even to claim PE as an original concept, since all of the tenets of allopatric speciation and the conclusions labelled as PE were stated by Charles Darwin over 100 years before Eldredge and Gould proposed their "novel" hypothesis. [7]
Alternative explanations for the punctuated pattern of evolution observed in the fossil record. Both macromutation
and relatively rapid episodes of gradual evolution could give the
appearance of instantaneous change, since 10,000 years seldom registers
in the geological record. Image: By Ian Alexander - Own work, CC BY-SA 4.0
As one can see, Gliedman's assertions have not stood the test of time. What about his assertion that "no fossil or other physical evidence directly connects, man to ape"? His claim that no fossil evidence directly connects man to ape reflects a poor grasp of palaeontology. We do not expect to find direct ancestors in the fossil record. Rather, we aim to build relations between species. As Louise Mead points out:
The ancestor of two living forms is unlikely to be found alive because it would have been outcompeted in most cases by newly adapting forms, and an extinct ancestor of two living forms would not be expected to look intermediate between them. Today, evolutionary biologists and paleontologists do not focus on finding “intermediates” but rather on reconstructing evolutionary relationships and history using shared derived characters or synapomorphies. Willi Hennig revolutionized systematics in the 1960s with the introduction of cladistics, which ushered in a new method of phylogenetic analysis and a new approach to systematics. Instead of relying on a Linnaean system of classification, cladistics placed the focus on evolutionary history, specifically identifying features as ancestral (general) or derived (evolved after the lineage split from the ancestor). If a shared derived character or synapomorphy is found in two or more related organisms, it is inferred to have been present in their common ancestor, irrespective of whether or not there is a fossil record for that ancestor... Rather than trying to find the actual fossil corresponding to the “missing link” between lobe-fins and tetrapods, paleontologists instead look for fossils with characters or features important for an adaptive transition from life in an aquatic environment to life on land and that are shared as the result of common ancestry. [8]His assertion that there is a "lack of a missing link to explain the relatively sudden appearance of modern man" makes the classic error of referring to a 'missing link', a concept that has no meaning in systematics. Mead again:
The concept of a “missing link” is an “archaic expression”… tracing back to the Great Chain of Being, a view of the physical and metaphysical world as an unbroken chain. It was later temporalized by the evolutionary thought of the eighteenth and nineteenth century to the idea of evolution as a progressive climb up a ladder… These views of evolution create the false expectation that there should be fossil evidence showing “a complete chain of life from simple to complex”. [9]While the hominin fossil record is unlikely ever going to be complete enough to allow a 100% accurate reconstruction of the human family tree, it is comprehensive enough to show the broad large-scale structure of human evolution, including our relationship to the apes.
The idea that modern man appeared suddenly is incorrect. The fossil record shows a clear trend towards obligate bipedality and increasing cranial capacity, the latter clearly demonstrated by a plot of cranial size versus time:
It seems to me that every popular-level discussion of human evolution should use this sort of chart as much as possible. Creationists should be embarrassed and ashamed about the huge mass of evidence they ignore every time they fail to mention the stunning, overwhelming, transitional, gradual, nature of the hundreds of ancient fossil skulls that have been discovered since Darwin and Huxley postulated apelike ancestors for humans back in the 1800s. The evidence is simply an astonishing confirmation of evolution, and the endless pages of creationist diatribes about the lack of transitional hominid fossils are revealed to be mere verbal obfuscation when compared to this simple chart. [10]I have refrained so far from referring to the single-most compelling line of evidence that confirms human-ape common ancestry, namely the myriad shared genetic elements such as retrotransposons, pseudogenes, and ERV elements, simply because the appeal to Gliedman's article is so easily dismissed without referring to it. [11] However, as even the leading intelligent design advocate Michael Behe concedes, the evidence for human-ape common ancestry from the genomic data is overwhelming:
When two lineages share what appears to be an arbitrary genetic accident, the case for common descent becomes compelling, just as the case for plagiarism becomes overpowering when one writer makes the same unusual misspellings of another, within a copy of the same words. That sort of evidence is seen in the genomes of humans and chimpanzees. For examples, both humans and chimps have a broken copy of a gene that in other mammals helps make vitamin C As a result, neither humans nor chimps can make their own vitamin C. Of an ancestor of the two species originally sustained the mutation and then passed to both descendant species, that would neatly explain the situation.
More compelling evidence of the shared ancestry of humans and other primates comes from their hemoglobin - not just their working haemoglobin, but a broken haemoglobin gene, too. In one region of our genomes humans have five genes for proteins that act at various stages of development (from embryo through adults) as the second (betalike) chain of haemoglobin. This includes the gene for the beta chain itself, two almost identical copies of a gamma chain (which occurs in fetal haemoglobin), and several others. Chimpanzees have the very same genes in the very same order. In the region between the two gamma genes and a gene that works after birth, human DNA contains a broken gene (called a "pseudogene") that closely resembles a working genre for a beta chain, but has features in its sequence that preclude it from coding successfully for a protein.
Chimp DNA has a very similar pseudogene at the same position. The beginning of the human pseudogene has two particular changes in two nucleotide letters that seem to deactivate the gene. The chimp pseudogene has the exact shame changes A bit further down in the human pseudogene is a deletion mutation, where one particular letter is missing. For technical reasons, the deletion irrevocably messes up the gene's coding. The very same letter is missing in the chump gene. Towards the end of the human pseudogene another letter is missing. The chimp pseudogene is missing it too.
The same mistakes in the same gene in the same positions of both human and chimp DNA. If a common ancestor first sustained the mutational mistakes band subsequently gave rise to these two modern species, that would very readily account for both why both species have them how. It's hard to imagine how there could be stronger evidence for common ancestry of chimps and humans.
That strong evidence from the pseudogene points well beyond the ancestry of humans. Despite some remaining puzzles, there's no reason to doubt that Darwin had this point right, that all creatures on earth are biological relatives. (Emphasis mine) [12]
Irrespective of whether the Christadelphian evolution denialist who appealed to Gliedman read the Science Digest article in which the argument appeared, or discovered the quotation in another special creationist article, the fact that he failed to check a thirty-six year old article to see if Gliedman's assertion was backed by the evidence represents a major failure in fact-checking. James 3 reminds us that those who aspire to be teachers will be held to a higher standard given the importance of ensuring that what they teach is true. Monumental failures to adequately verify references such as this remind us of the importance of this apostolic principle.
References
1. This term has its own acronym - PRATT. After a while, it is easier to simply point people to a FAQ list given the failure of special creationists to recognise that their talking points were debunked ages ago.
2. Pearson M "Because Truth Matters" The Fourth Conversation 24th January 2018
3. Gliedman, John. 1982. Miracle Mutations. Science Digest. 90(2):90-96.
4. The Wikipedia entry on Science Digest comments on its last six years of life, "In November 1980 the magazine was expanded to an 11 x 8 inch glossy page format with full-length articles and color pictures targeted at a college-educated reader. The new version was largely the creation of its then editor Scott DeGarmo. It was issued bi-monthly with circulation of about 500,000 copies. At first it tended to favor breathless cover lines, and often turned to pseudoscience topics, including spontaneous human combustion and UFOs. Unable to compete with more serious publications, such as Discover and Omni, the magazine ceased publication in 1986." Being described as a less serious publication than Omni is frankly damning, given Omni's penchant for covering pseudoscience such as parapsychology.
5. Bergman J "Some Biological Problems With The Natural Selection Theory" CRSQ Volume 29, Number 3, December 1992. It is worth noting that Bergman's citation of Gliedman's article is in error, referring to its title as "Mutations" rather than "Miracle Mutations". Sloppiness in minor details does not engender confidence in the big picture.
6. Keith Miller "The Cambrian 'Explosion', Transitional Forms, and the Tree of Life" BioLogos December 3, 2010
7. Douglas Theobald "All you need to know about Punctuated Equilibrium (almost)"
8. Mead L.S. "Transforming Our Thinking about Transitional Forms" Evo Edu Outreach (2009) 2:310-314
9. ibid, p 310
10. Matzke N "Fun with Hominin Cranial Capacity Datasets (and Excel)" Panda's Thumb September 30, 2006
11. The evidence from shared endogenous retroviral elements alone makes the case beyond reasonable doubt. See this article of mine for more details.
12. Behe M The Edge of Evolution: The Search for the Limits of Darwinism (2007: Free Press) p 71-72
5. Bergman J "Some Biological Problems With The Natural Selection Theory" CRSQ Volume 29, Number 3, December 1992. It is worth noting that Bergman's citation of Gliedman's article is in error, referring to its title as "Mutations" rather than "Miracle Mutations". Sloppiness in minor details does not engender confidence in the big picture.
6. Keith Miller "The Cambrian 'Explosion', Transitional Forms, and the Tree of Life" BioLogos December 3, 2010
7. Douglas Theobald "All you need to know about Punctuated Equilibrium (almost)"
8. Mead L.S. "Transforming Our Thinking about Transitional Forms" Evo Edu Outreach (2009) 2:310-314
9. ibid, p 310
10. Matzke N "Fun with Hominin Cranial Capacity Datasets (and Excel)" Panda's Thumb September 30, 2006
11. The evidence from shared endogenous retroviral elements alone makes the case beyond reasonable doubt. See this article of mine for more details.
12. Behe M The Edge of Evolution: The Search for the Limits of Darwinism (2007: Free Press) p 71-72
