Malaria’s diminished chloroplast is on purpose? Really?
This post is a kind of follow-up to this post.
Behe seems to have learned that taking the offensive is often the best strategy (especially since he has no hope in playing by the rules of science discussion). Rather than answering our questions about what parasites were designed to do, and what purpose they serve, he uses Plasmodium falciparum, the organism which causes malaria, as his test case for what evolution can do, while he assigns everything that evolution supposedly cannot do to “design”. In fact, he doesn’t in the slightest try to show that life is not the result of inheritance and accident, plus selection, rather he wants to claim that this is not so because life is just “too complex” to have evolved, and so, in his usual resort to false dichotomy, he resorts to “design”.
But we have no reason to follow the channel of “thought” that he attempts to impose because he lacks any kind of evidence for design. As I have demonstrated repeatedly, life’s characteristics are often due to accident (either accident of inheritance, or of various kinds mutations, duplications, etc.), and many of the “irreducibly complex” characteristics such as the chloroplast and its integration into the cells of many eukaryotes have very clear indications of being due to accident plus a considerable amount of complex evolution–notably the evolution of transport mechanisms after engulfment by a (proto?)eukaryotic cell, with respect to the chloroplast. As noted above, I wrote a post regarding this previously.
Remarkably, P. falciparum contains the remains of a chloroplast, which is called an “apicoplast.” What is currently believed to be the case is that an ancestor of the malaria parasite engulfed, not a cyanobacterium, rather a red alga which had cyanobacterium-derived chloroplasts within it. All that remains today is the apicoplast, which has only a very small genome (32 kb), and evidently no genes for photosynthesis. Oddly enough, relatively few of the proteins targeted to this apicoplast actually derive from the chloroplast from which it evolved. Nature article used as a source for this paragraph (the fact that it was a red alga, not a green one as related in the link, is to be found in Moore, et al. “A photosynthetic alveolate closely related to apicomplexan parasites” Nature 21 Feb. 2008 451: 959-963)
The details are in sources like the on in the link just above. What I want to mention are the many accidents involved in the origination of this “irreducibly complex” and essential organelle used by P. falciparum to parasitize humanity.
First, rather than design providing photosynthesis to eukaryotes, a eukaryotic cell had to engulf a cyanobacterium without digesting it, in order to provide a very crude photosynthetic symbiosis. Subsequently, transport mechanisms evolved (though Behe denies the possibility), genes were transferred to the nuclei of the algae (some of these algae evolved into plants) containing what became these chloroplasts, and regulatory functions of the chloroplasts evolved as well. If any design or identifiable purpose can be found in any of these changes, no one has adequately shown their existence.
After all of that evolution happened, the ancestor of P. falciparum secondarily engulfed a red alga, and a symbiotic relationship evolved. While little is actually known specifically about this evolution, no doubt P. falciparum’s ancestor had to evolve essentially the same transport, regulatory, and genetic changes that already occurred in the red alga’s ancestor. It seems that eventually all of the red alga except for the chloroplast (and likely a number of genes from the red alga transferred to the nucleus) disappeared. The chloroplast itself lost most of its functions, including photosynthesis, as what became a parasite quite early in evolution (early in metazoan evolution, at least) no longer needed many of those functions.
This is an extraordinarily convoluted story, one that only makes sense, as famously stated, in the light of evolution. Can anyone actually understand this as a “design strategy”? It most certainly is not, it is a story of accident and of adaptation of various accidents to the evolving needs of a lineage of (eventually) parasitical organisms. And yet Behe would like to credit all of these “irreducibly complex” accidents, and complex adaptations to those accidents, to “design”.
Then again, why not do so from his amoral and nihilistic view of “design”? Only someone grasping without cause or reason would look at the destructive relationship of P. falciparum, Anopheles mosquitoes, and humans, as having been purposely designed instead of itself being an obvious evolutionary accident. Evolution explains such relationships, because it has no inherent moral aim or purpose (or any other kind of aim or purpose), nor any preference for host over parasite or for parasite over host. What we see in the human-mosquito-malaria relationship is at best inexplicable in terms of design and of purpose, and at worst an indictment of the God that Behe blames for malaria.
In addition to the foregoing comments, I would like to bring up a sound principle that I mentioned while discussing DBB, here. William Paley wrote:
In this cause, therefore, we ought to rest; in this cause the common sense of mankind has, in fact, rested, because it agrees with that which in all cases is the foundation of knowledge,–the undeviating course of their experience. The reasoning is the same as that by which we conclude any ancient appearances to have been the effects of volcanoes or inundations, namely, because they resemble the effects which fire and water produce before our eyes; and because we have never known these effects to result from any other operation. William Paley Natural Theology Chap. 23
What does experience, observation, and evidence suggest about the causes of the changes that have occurred to P. falciparum, and especially with respect to its apicoplast? What does experience and observation suggest regarding parasitical relationships? Even Behe admits that experience and observation provide evidence that contingency and selection produce identifiable evolutionary patterns in life. He simply wants everyone to forget that what we see in his “irreducibly complex” examples is the same sort of combination of accident, selection, and inherited contingency that we see in his examples of evolution. But if accident can be identified in “microevolution” due to its evident contingent character, how is not applying the same standard to “macroevolution” to be justified?
All that is evident in the history of life is accident and heredity being worked over by selection. Only by ignoring every principle of design and every principle of evolution can Behe find his way to ignoring the plain evidence that life evolved without guidance, and to instead believe that somehow the highly complex relationship between cyanobacterium, red alga, two eukaryotes engulfing and symbiosing with photosynthesizers, Anopheles, and humanity, is a purposeful arrangement of parts.
Experience and observation tell us that such a relationship is produced by identified and unguided evolutionary processes.
This is part of a series of posts that I am combining into one long post, which may be found at The Edge of Evolution>