This little book is one of a class that was more common twenty years ago, when any acute literary critic thought he could demolish Darwin. Mr. Syme has, however, the advantage of having read some of the best works both for and against Darwinism, and is thus able to support his views by quoting writers of eminence. He begins boldly. In the table of contents of the first chapter we find such headings as, “A fatal admission—Darwin’s definition misleading—Refutes his own theory.” But when we look for the proof of these statements we find they rest on misconception, misrepresentation, or misquotation. A few examples will show that this is the case. – Alfred Russel Wallace 1891. Another darwinian critic. Nature 43 (1119): 529-530.
The above quote from Alfred Russel Wallace comes from his review of On the Modification of Organisms by David Syme. As the quote shows, criticizing Darwin as been a cottage industry since on the Origin of Species was published in 1859. As the above quote also shows, the reliance on misconception, misrepresentation, and misquotation has been a standard tactic in the arsenal of creationists for over one hundred years. As we will see below (and in future posts), the latest entry, Science and Human Origins, in the cottage industry continues this illustrious tradition.
Science and Human Origins was written by Ann Gauger, Douglas Axe, and Casey Luskin. Science and Human Origins was published by the Discovery Institute earlier this year and created quite ruckus in the science blogosphere when it did. You can see this post (and the links therein) for additional details. Originally I was just going to review the section on fossils but have decided to review the entire book – or at least those parts I feel competent to deal with. This post looks at chapter one.
The first chapter is authored by Ann Gauger. The chapter is broken into six sections and I will look at each section in turn.
What is the evidence for common ancestry?
In this section Gauger posits that there are two major lines of evidence supporting the descent of humans from their common ancestor with apes. These are the comparative analysis of DNA sequences and anatomical similarities and differences. I will look at her view of anatomy and fossils first. Here is Gauger:
The fossil evidence for our evolution from apes is actually quite sketchy.3 Ancient hominin fossils are rare, and they typically consist of bone fragments or partial disarticulated skeletons obtained from different locations around the world and from different geologic strata. They fall into two basic categories: ape-like fossils and human-like fossils. This discontinuity between types is well-known. Nonetheless, the hominin fossils have been interpreted as historical, physical evidence of our common ancestry with apes.
There are several issues involved here so lets take them in order. First, is the supposed sketchiness of the fossil record. I have addressed this argument here and here. In reality we have quite a bit of fossil material pertaining to human evolution. A simple perusal of, say, the three volume Catalogue of Fossil Hominids put out by the British Museum, the Guide to Fossil Man by Day, the four volume series The Human Fossil Record by Schwartz and Tattersall, or heck, even Wood’s masterpiece Koobi Fora Research Project Vol 4 Hominid Cranial Remains would make abundantly clear the amount of material we have. Second, bone fragments. This comment betrays a complete lack of understanding of anatomy and morphology. While one would prefer a whole bone, in reality a lot can be told from a bone fragment if it contains any relevant anatomical landmarks such as muscle origins and insertion points. We don’t, for example, need the entire femur to tell if a hominin is bipedal or not – we just need enough of the distal femur to measure the bicondylar angle. You can see here for posts on some of the things we can learn from bone fragments. Third, disarticulated skeletons from different locations or different geologic strata. I am not sure how to parse this. I think this partially refers to Luskin’s trip to see Lucy (which I have examined here. For more on Luskin and Lucy, see here.) I think it also refers to standard arguments about the geologic column by creationists. The only thing I can really say to this is that, yeah, neanderthals are found in different geographic locations and different strata than Homo erectus, which in turn is found in different geographic locations than say, the australopithecines or modern humans. Fourth, two basic categories; ape-like and human-like fossils. This is straight up creationism. For the paleoanthropologist the situation is somewhat more complex. By way of an example, Luskin – in chapter three – cites a paper by Bromage and Dean in support of his argument for this dichotomy. The Bromage and Dean paper looked at what perikymata can tell us about the growth patterns of fossil hominins. They conclude that fossil hominin growth patterns are similar to those of modern great apes. I can understand how one can leap to the conclusion that there are ape-like fossils and there are human like fossils and nothing in between. What then are we to make of one of the footnotes to Bromage and Dean’s Table 1:
In addition to the importance perikymata have in aging studies, their spacing on the incisor crown surface appears to differentiate certain hominid taxa. Modern human teeth are reported as having perikymata that are more widely spaced toward the occlusal surface becoming more closely packed toward the cervix. This also appears in the study sample of teeth of Australopithecus and early Homo. The teeth of Paranthropus observed in this study, however, do not show such a marked narrowing and condensation of perikymata cervically. [the rest of the note talks about an isolated incisor found at Swartkrans – afarensis]
The fact that growth patterns are similar to apes while other measures indicate similarity to modern humans can hardly be fit in such a simple dichotomy as the one Gauger says exists. Or what about this paper by Richmond and Jungers which performed a multivariate analysis of the femur of the great apes, modern humans, fossil Homo, various australopithecines, and Orrorin and found that the femur of the australopithecines fell between that of the great apes on one hand, and that of fossil Homo and modern humans on the other hand. This does not fit in Gauger’s dichotomy either.
As for analysis of DNA, Gauger dismisses studies of molecular evolution in one short paragraph:
The evidence from DNA comparisons is similarly enigmatic. DNA sequences are strings of nucleotides millions or billions in length. Aligning DNA sequences in order to compare them is a tricky business. There can be single base changes, insertions or deletions, and rearrangements of the DNA that complicate things and may or may not be included in comparisons. (Here she inserts a footnote referring the reader to Luskin’s chapter on chromosomal rearrangements.) The degree of similarity calculated depends on how the analysis is done, and what is excluded and included. (Here she inserts a footnote referring the reader to an article by Todd Wood a noted creationist). But putting aside arguments about how similar we are to chimps, the question is: What does similarity demonstrate?
I’m not a molecular biologist, but this blank assertion, sans any supporting evidence hardly seems a convincing reason to chuck all the research that’s been done in the field out the window. Gauger wants to argue that biologist and such assume that similarity means common ancestry and that this is a bad thing, and yet we have just seen above (and will see below) Gauger assuming that similarities between australopithecines, H. habils, and the great apes means that these are apelike and that the similarities between H. erectus and modern humans means H. erectus is human. This is a common thread throughout the book, all three authors accuse biologists and paleoanthropologists of focusing exclusively on similarities and ignoring differences, and ignore the fact that in order to make their case they have to ignore differences and focus on similarities. It’s almost they have never heard of Henning or Wiley. The argument is two-fold. First, spend too much time on symplesiomorphies, and ignore synapomorphies and autapomorphies. Second, symplesiomorphies can not be used to infer common descent. This latter is correct but the former is not. Gauger concludes this section by arguing that:
For any story about common ancestry to be verified, including the proposed story of our common ancestry, two things must be shown. First, a step-wise adaptive path must exist from the ancestral form to the new form, whether it is to a new gene, a new protein, or a new species; and second, if it is to have happened by an unguided, neo-Darwinian mechanism, there must be enough time and probabilistic resources for neo-Darwinian to traverse that path.
In one sense, the first part of this is somewhat correct, there does need to be a path from ancestor to descendent, however the extent to which it needs to be adaptive, or stepwise, is debatable. The larger point, that such a path is required to verify common descent is debatable. We can, for example come up with some predictions about what we would expect to see if common ancestry is true and then go out and see if those predictions are confirmed by the new protein, gene, or species. For example, if chimps and humans shared a common ancestor, what would we expect a member of the hominin lineage to look like 4 mya, or 2 mya? If we make a prediction about this and the fossil record matches our prediction we can say that common ancestry is provisionally confirmed. We do not need to know a step by step path from one to the other – although it would be icing on the cake if we did. As for the second, this is Dembskian upper probability bound obfustication.
An Experimental Test
In this section Gauger discusses this paper The paper discusses the attempt by her and Axe to convert one protein to another. Since this also forms the bulk of chapter two I will put off discussion until I review chapter two. However, one statement in this section deserves discussion.By way of background, this section discusses attempts by Gauger and Axe to convert one into another. Something they claim must be possible if evolution is true and it should be easy to achieve. Gauger then says:
Yet when we experimentally determined how many mutations it would take, we found that it would take at least seven mutations to evolve one enzyme into the other – too many mutations to have occurred by an unguided neo-Darwinian process.
This is an odd claim for Gauger to make. Because this kind of thing happens all the time, take RNASE1 and RNASE1B for example. These occur in colobines. RNASE1B is a duplication of RNASE1 and is expressed in the small intestine and there are nine mutations between it and RNASE1 – seven of which alter the charge and isoelectric point. The upshot is that RNASE1B is about six times more active in a low pH environment (such as in the colobine small intestine). This example comes from Zhang et al 2002 and they conclude:
Fossil records show the emergence of leaf-eating and foregut fermentation in colobines no later than 10 Myr ago… [reference omitted – afarensis], predating the origin of RNASE1B. This suggests that changes in diet and digestive physiology in colobines provided the selective forces for the evolution of a more effective digestive RNase, whereas gene duplication provided the raw genetic material. We also note the temporal
proximity of the gene duplication and the radiation of Asian colobines about 3.5 Myr ago20, which, together with the presence of RNASE1B in at least two genera of Asian colobines (Pygathrix and Presbytis), suggests the possibility of a causal link between these events.
Something similar occurs in ruminants, only in this case five mutations are responsible for the change in function (degrading double stranded RNA). What makes this interesting is that these five mutations are completely different from the nine mutations in colobines. This led Zhang (2003) to ask how many sites affect the function which turns out to be somewhere between 16 and 44. I will have more to say about this paper in the next section. At this point, because this review is already getting long, I will break this review of chapter one into two sections. So, in the next post I will start with Getting To Human.
NOTE: Never try to correct typos and close tags via a smartphone…
Bromage and Dean (1985) Re-evaluation of the age at death of immature fossil hominids. Nature 317:525-527
Richmond and Jungers (2008) Orrorin tugenensis Femoral Morphology and the Evolution of Hominin Bipedalism. Science 319:1662-1665
Zhang et al (2002) Adaptive evolution of a duplicated pancreatic ribonuclease gene in a leaf-eating monkey. Nature Genetics 30(4):411-5.
Zhang (2003) Parallel Functional Changes in the Digestive RNases of Ruminants and Colobines by Divergent Amino Acid Substitutions. Molecular Biology and Evolution 20(8):1310-1317
Zhang (2006) Parallel adaptive origins of digestive Rnases in Asian and African Leaf Monkeys Nature Genetics 38:819 – 823