Monday, 10 June 2013

Examples of poor Christadelphian anti-evolution arguments - 3

The Testimony magazine [1] is a Christadelphian publication dedicated to Biblical study and apologetics, and along with the flagship journal The Christadelphian is considered something of an institution within our community. Unfortunately, its coverage of scientific questions relating to the Bible is frankly embarrassing. While our community has traditionally remained opposed to evolutionary biology, up until recently it accepted the evidence for an ancient earth [2], The Testimony  has included articles which advance long-refuted young earth creationist attacks  on radiometric dating [3] or seriously entertain the belief that non-avian dinosaurs coexisted with human beings, and inspired the stories about dragons found in many cultures [4]. Intellectually debased  material such as this is an embarrassment to our community.

Current science editor David Burges often invokes an unsophisticated form of the design argument in the magazine when attempting to rebut evolution. One example was the neck of the giraffe, which special creationists try to claim poses a major problem for evolution. After a cursory review of giraffe anatomy and physiology, he asserted that:
Everything about the giraffe points to a creature whose anatomy and features are unique and designed as a complete package. The authors of the most recent study, in dismissing sexual selection, conclude: “Better explanations for neck elongation must be sought elsewhere”. That ‘elsewhere’ is in the Word of God, which assures us that “God made the wild animals of the earth of every kind, and . . . saw that it was good” (Gen. 1:25, NRSV) and that He created all things for His (and our) pleasure (Rev. 4:11). [5]
Burges' conclusion was driven by the argument from personal incredulity, hardly grounds for such a cavalier dismissal of evolutionary biology. The origin of the giraffe's neck is still an area of active research, but the absence of a satisfactory evolutionary explanation does not mean one will never be found. More to the point, although we do not have a universally agreed evolutionary explanation for the neck of the giraffe, the fossil record is consistent with an evolutionary origin of the giraffes.

Evolution of the giraffe family. The modern okapi is more typical of the group, with its short neck and relatively short horns or “ossicones.” Some fossil giraffids, however, had very unusual branching and flaring cranial appendages. Only the lineage of the modern giraffe evolved a long neck. Source: Prothero Evo Edu Outreach (2009) 2:289-302

Vertebrate palaeontologist Donald Prothero (who it hardly needs to be said is in a much better position to provide an informed, credible opinion about the subject than Burges) points out:
Creationists often scoff at the notion that there are fossils that show how the giraffes evolved, but they could not be more mistaken. In fact, the giraffids have an excellent fossil record, although nearly all giraffes (both extinct and living) are short-necked, much like the modern okapi. Only the living genus Giraffa has the long neck that we consider typical of the group. All the rest of the giraffids were not only short-necked but sported a wide variety of cranial appendages. Some, like Sivatherium, were stocky moose-like creatures with broad palmate horns somewhat like those of a moose. Others, like Climacoceras, looked more like deer or antelopes. Despite these superficial convergences, they all show the characteristic hallmarks of giraffids in their teeth, skulls, and skeletons.
Most of these taxa are known from skulls and jaws and a few from skeletons, but the neck vertebrae are not often preserved. However, Nikos Solounias (2007, personal communication) is currently publishing a description of a new fossil of the giraffid Bohlinia that preserves a neck that is intermediate in length between Giraffa and the okapi. Thus, we do know how the giraffe got its long neck, and we have the transitional fossils to show how and when it occurred! Once again, the fossil record has provided a specimen whose very existence the creationists have long denied. [6]

Neck vertebrae of a recently discovered fossil giraffid Bohlinia that is intermediate in length between those of primitive giraffids (Okapia, bottom) and the modern long-necked species (Giraffa, top). This amazing discovery is a true “missing link” between okapis and the long-necked modern species (drawing courtesy of N. Solounias). Source: Prothero Evo Edu Outreach (2009) 2:289-302

In addition to resorting to the argument from personal incredulity, Burges has also made the mistake common to almost all creationists - failing to differentiate between the fact of evolution (as demonstrated in the fossil record, biogeography, comparative anatomy and molecular genetics) and the currently accepted theory of how that evolutionary change occurred. With respect to the neck of the giraffe, while a satisfactory evolutionary explanation for how it obtained its neck is pending, we have an excellent fossil record which includes a transitional giraffid fossil complete with neck length intermediate between the okapi and the giraffe. It is somewhat presumptuous for Burgess to dismiss evolutionary explanations for the origin of the neck and leg length of the giraffe as based not "on evidence, but rather on armchair reasoning that turns out to be incorrect." [7] when Burges fails to mention the fossil evidence for giraffe evolution.

His assertion that "[e]verything about the giraffe points to a creature whose anatomy and features are unique and designed as a complete package" overlooks one aspect of giraffe anatomy which is impossible to recognise with the 'perfect design equals intelligent designer' theme he is advancing, and that is the giraffe recurrent laryngeal nerve.

The recurrent laryngeal nerve is a branch of the vagus nerve, one of the twelve cranial nerves, and is one of the nerves that innervate the larynx. From its origin off the vagus nerve to its destination at the larynx is a distance of only a few centimetres. However, instead of passing directly to the larynx, it takes a totally pointless detour down the neck into the chest, loops under the aorta (the largest artery in the body, which emerges directly from the left ventricle of the heart) and then ascends up the neck to the larynx. There is no reason for this detour, and one is entitled to ask why would a designer adopt such a strange pathway for a nerve. In humans, we can see how wasteful and this detour is:

Recurrent laryngeal nerve in human

Suboptimal design by itself does not prove common descent or evolution, though it poses the problem of why an omnipotent Creator produces such suboptimal designs when there is no reason for them. However, if the same design flaw is found in multiple organisms in the same group, then the idea of common descent becomes a far more parsimonious explanation. One would expect a suboptimal feature in an ancestral species to be inherited by its descendants. Special creation is forced to posit multiple independent creation events with the same flaw being repeated every time. Again, God can create an animal with a nerve directly passing to the larynx - there is absolutely no physiological need for this detour. Occam's razor would suggest common descent as the most parsimonious explanation, with the original design flaw occurring in the common ancestor of all tetrapods, and being inherited by its descendants.

The giraffe is the most spectacular demonstration of the path of the recurrent laryngeal nerve. As with other mammals, it goes past the larynx, down its long neck, under its aorta and up to the larynx. In humans, the wasted length of recurrent laryngeal nerve is several centimetres. In the giraffe, the distance is measured in metres:

Recurrent laryngeal nerve in giraffe

The evolutionary biologist Mark Ridley explains the reason behind this wasteful anatomical quirk:
Evolution by natural selection proceeds in small, local steps and each change has to be advantageous in the short term. Unlike a human designer, natural selection cannot favour disadvantageous changes in the knowledge that they will ultimately work out for the best. As Wright emphasised in his shifting balance model...natural selection may climb to a local optimum, where the population may be trapped because no small change is advantageous, though a large change could be. As we saw, selection itself (when considered in a fully multidimensional context), or neutral drift, may lead the population away from local peaks; but it also may no. Some natural populations now may be imperfectly adapted because the accidents of history pointed their ancestors in what would later become the wrong direction. 
The recurrent laryngeal nerve provides an amazing example. The laryngeal nerve is, anatomically, the fourth vagus nerve, one of the cranial nerves. These nerves first evolved in fish-like ancestors. As figure 10.12a shows, successive branches of the vagus nerve pass, in fish, behind the successive arterial arches that run through the gills. Each nerve takes a direct route from the brain to the gills. During evolution, the gill arches have been transformed; the sixth gill arch has evolved in mammals into the ductus arteriosus, which is anatomically near to the heart. The recurrent laryngeal nerve still follows the route behind the (now highly modified) "gill arch":  in a modern mammal, therefore, the nerve passes from the brain, down the neck, round the dorsal aorta, and back up the larynx. 
In humans, the detour looks absurd, but it is only a distance of a foot or two. In modern giraffes, the nerve makes the same detour, but it passes all the way down and up the full neck of the giraffe's neck. The detour is almost certainly unnecessary and probably imposes a cost on the giraffe (because it has to grow more nerve than necessary and signals sent down the nerve will take more time and energy). Ancestrally, the direct route for the nerve was to pass posterior to the aorta; but as the neck lengthened in the giraffe's evolutionary lineage the nerve was led on a detour of increasing absurdity. If a mutant arose in which the nerve went directly from brain to larynx, it would probably be favoured (though the mutation would be unlikely if it required a major embryological reorganization); the imperfection persists because such a mutation has not arisen (or it arose and was lost by chance). The fault arose because natural selection operates in the short term, with each step taking place as a modification of what is already present. This process can easily lead to imperfections due to historical constraint - though most will not be as dramatic as the giraffe's recurrent laryngeal nerve. [8 ]

Evolution of the recurrent laryngeal nerve. (a.) In fish, the vagus nerve sends direct branches between successive gill arches. (b.) In mammals, the gill arches have evolved into a very different circulatory system. The descendant nerve of the fish's fourth vagus now passes from the brain, down to the heart (in the thorax) and back up to the larynx. Redrawn, by permission of the publisher, from Strickberger (1990), modified from de Beer (1971).

The suboptimal path of the recurrent laryngeal nerve in the giraffe can be seen in the dissection of the giraffe below:

Evolution is constrained - it cannot work from a fresh sheet, but starts with what it is given, which in this case is the basic fish-like anatomy, which explains neatly the origin of this quirk. With special creation, there is no constraint, so design can be as elegant and efficient as possible. The fact that all mammals are flawed in exactly the same way is difficult at best to square with special creation, but follows easily from common descent.

The absence of any reference to the recurrent laryngeal nerve in Burges' article on the neck of the giraffe is inexcusable, as this is common knowledge in anyone remotely acquainted with vertebrate comparative anatomy. Burges claimed that "everything about the giraffe points to a creature whose anatomy and features are unique and designed as a complete package." Given what we've seen about the wasteful, incompetent design of the giraffe recurrent laryngeal nerve, such a claim is simply impossible to sustain.

It's unacceptable for special creationists to claim that aesthetically pleasing elements of the natural world are proof of intelligent design, but ignore flawed, suboptimal or frankly incompetent design, such as the path taken by the recurrent laryngeal nerve in mammals. As mentioned before, flawed design is not 'proof' of evolution, as it is conceivable for a supernatural designer to produce flawed design. However, when elegant design is used as the metric by which the natural world is judged to be the product of a Divine creator, consistency demands that a theological inference be drawn from botched design, as well as the elegant. If God is responsible for the elegance of the rete mirabile, He is also responsible for the utterly flawed, wasteful design of the recurrent laryngeal nerve. Burges has only told part of the story of the neck of the giraffe, once again showing how poorly researched and tendentious his article is.

Unfortunately, The Testimony abounds with anti-evolutionary articles that like this one are naive, poorly researched and advance arguments that were refuted years ago. Whatever good it achieves in other areas is hopelessly compromised by anti-evolutionary articles which are  fundamentalist in their tone. The danger here is that we will be judged by the abysmal quality of this special creationist nonsense, rather than the strength og our theological message, a point that none other than Augustine made over 1500 years ago:
Usually, even a non-Christian knows something about the earth, the heavens, and the other elements of this world, about the motion and orbit of the stars and even their size and relative positions, about the predictable eclipses of the sun and moon, the cycles of the years and the seasons, about the kinds of animals, shrubs, stones, and so forth, and this knowledge he holds to as being certain from reason and experience. Now, it is a disgraceful and dangerous thing for an infidel to hear a Christian, presumably giving the meaning of Holy Scripture, talking nonsense on these topics; and we should take all means to prevent such an embarrassing situation, in which people show up vast ignorance in a Christian and laugh it to scorn. The shame is not so much that an ignorant individual is derided, but that people outside the household of the faith think our sacred writers held such opinions, and, to the great loss of those for whose salvation we toil, the writers of our Scripture are criticized and rejected as unlearned men. If they find a Christian mistaken in a field which they themselves know well and hear him maintaining his foolish opinions about our books, how are they going to believe those books in matters concerning the resurrection of the dead, the hope of eternal life, and the kingdom of heaven, when they think their pages are full of falsehoods on facts which they themselves have learnt from experience and the light of reason? Reckless and incompetent expounders of holy Scripture bring untold trouble and sorrow on their wiser brethren when they are caught in one of their mischievous false opinions and are taken to task by those who are not bound by the authority of our sacred books. For then, to defend their utterly foolish and obviously untrue statements, they will try to call upon Holy Scripture for proof and even recite from memory many passages which they think support their position, although “they understand neither what they say nor the things about which they make assertion. (Emphasis mine) [9] 
This is why anti-evolution articles do more harm than good, and are simply embarrassing to any Christadelphian familiar with the evidence for evolution.



2. John Thomas, the founder of the Christadelphian community in his 1848 book Elpis Israel not only accepted the great age of the Earth, but referred his readers to the extant geological literature for more details on the matter.

3. Watts J "Calibrated Radiocarbon Dating" The Testimony  (2001) 71:206-209

4. Nicholls J "What happened to the dinosaurs?" The Testimony  (2001) 71:186-191

5. Burges D "How did the giraffe get its neck?" The Testimony (2010) 80:106-107

6. Prothero D "Evolutionary Transitions in the Fossil Record of Terrestrial Hoofed Mammals" Evo Edu Outreach (2009) 2:289-302

7.  Burges op cit  p 107

8. Ridley M Evolution (2004, Wiley-Blackwell) p 281-2

9. Augustine The Literal Meaning of Genesis. Translated and annotated by John Hammond Taylor, S.J. ( New York: Paulist Press, 1982.)