- A.C. McIntosh, “Evidence of design in bird feathers and avian respiration,”International Journal of Design & Nature and Ecodynamics, Vol. 4(2):154–169 (2009).
In this peer-reviewed paper, Leeds University professor Andy McIntosh argues that two systems vital to bird flight -- feathers and the avian respiratory system -- exhibit “irreducible complexity.” The paper describes these systems using the exact sort of definitions that Michael Behe uses to describe irreducible complexity:[F]unctional systems, in order to operate as working machines, must have all the required parts in place in order to be effective. If one part is missing, then the whole system is useless. The inference of design is the most natural step when presented with evidence such as in this paper, that is evidence concerning avian feathers and respiration.Regarding the structure of feathers, he argues that they require many features to be present in order to properly function and allow flight:[I]t is not sufficient to simply have barbules to appear from the barbs but that opposing barbules must have opposite characteristics -- that is, hooks on one side of the barb and ridges on the other so that adjacent barbs become attached by hooked barbules from one barb attaching themselves to ridged barbules from the next barb (Fig. 4). It may well be that as Yu et al.  suggested, a critical protein is indeed present in such living systems (birds) which have feathers in order to form feather branching, but that does not solve the arrangement issue concerning left-handed and right-handed barbules. It is that vital network of barbules which is necessarily a function of the encoded information (software) in the genes. Functional information is vital to such systems.He further notes that many evolutionary authors “look for evidence that true feathers developed first in small non-flying dinosaurs before the advent of flight, possibly as a means of increasing insulation for the warm-blooded species that were emerging.” However, he finds that when it comes to fossil evidence for the evolution of feathers, “None of the fossil evidence shows any evidence of such transitions.”
Regarding the avian respiratory system, McIntosh contends that a functional transition from a purported reptilian respiratory system to the avian design would lead to non-functional intermediate stages. He quotes John Ruben stating, “The earliest stages in the derivation of the avian abdominal air sac system from a diaphragm-ventilating ancestor would have necessitated selection for a diaphragmatic hernia in taxa transitional between theropods and birds. Such a debilitating condition would have immediately compromised the entire pulmonary ventilatory apparatus and seems unlikely to have been of any selective advantage.” With such unique constraints in mind, McIntosh argues that “even if one does take the fossil evidence as the record of development, the evidence is in fact much more consistent with an ab initio design position -- that the breathing mechanism of birds is in fact the product of intelligent design.”
The design aspects of bird feathers and the lung design were first brought to my attention years ago in Michael Denton's book Evolution: A Theory in Crisis (Adler & Adler, 1985). In discussing the bird lung design in relation to all other vertebrate lungs Denton writes:
McIntosh’s paper argues that science must remain at least open to the possibility of detecting design in nature, since “to deny the possibility of the involvement of external intelligence is effectively an assumption in the religious category.” Since feathers and the avian respiratory system exhibit irreducible complexity, he expressly argues that science must consider the design hypothesis:As examples of irreducible complexity, they show that natural systems have intricate machinery which does not arise in a “bottom up” approach, whereby some natural selective method of gaining small-scale changes could give the intermediary creature some advantage. This will not work since, first, there is no advantage unless all the parts of the new machine are available together and, second, in the case of the avian lung the intermediary creature would not be able to breathe, and there is little selective advantage if the creature is no longer alive. As stated in the introduction, the possibility of an intelligent cause is both a valid scientific assumption, and borne out by the evidence itself.
"Just how such an utterly different respiratory system could have evolved gradually from the standard vertebrate design is fantastically difficult to envisage, especially bearing in mind that the maintenance of respiratory function is absolutely vital to the life of an organism to the extent that the slightest malfunction leads to death within minutes." (pp. 211-212)Denton went on to conclude:
"The avian lung and the feather bring us very close to answering Darwin's challenge:
If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.
"In addition to the feather and the avian lung there are many other unique features in the biology of birds, in the design of the heart and cardiovascular system, in the gastrointestinal system and in the possession of a variety of other relatively minor adaptations, such as, for example, the unique sound producing organ, the syrinx, which similarly defy plausible explanations in gradualistic terms. Altogether it adds up to an enormous conceptual difficulty in envisaging how a reptile could have been gradually converted into a bird." (p. 213)The "watchmaker" is not "blind!" Those scientists committed to wearing the googles of naturalism are the ones with the questionable vision. Jesus told us to look at the birds of the air (Matthew 6.26) to see something of the Father's goodness. It appears that we can also look inside the birds of the air and see His intelligent design.