Saturday, 2 August 2014

Parasites and Creationists

Heligmosomoides polygyrus
Photo: Janice Murray & Maizels Laboratory/University of Edinburgh
I've commented before on how parasites are a problem for creationists and, apart from their understandable shyness at discussing parasitism, this probably explains why creationist loons who misrepresent science and misinform scientifically illiterate people for a living never seem to discuss parasites or explain how they fit into an intelligent design model, especially one in which the supposed intelligent designer is omnibenevolent and created everything just for humans.

For example, the leading Discovery Institute (aka Liars For Power and Money, Inc.) propagandist for ID, Michael Behe, avoids completely any reference to the fact that his 'intelligently designed' E. coli flagellum appears to have only one purpose - helping E. coli make us sick.

With their evident discomfort in mind then, it gives me great pleasure to invite creationists to comment on an article and two papers published recently in Science concerning how infection by a parasitic worm (helminth) can appear to aid other parasites by helping them overcome the body's natural immune responses. In particular, I would like them to explain how this phenomenon is better explained by their intelligent-design-by-an-omnibenevolent-designer-who-did-it-all-for-humans model than it is by Darwinian evolution by Natural Selection.

The article, which links directly to the two papers, by Rick M Maizels (Institute for Immunology and Infection Research and Centre for Immunity, University of Edinburgh, Edinburgh, UK) and William C Gause (Center for Immunity and Inflammation, Department of Medicine, New Jersey Medical School, Rutgers - the State University of New Jersey, Newark, NJ, USA) explains how infection by parasitic worms can activate latent infections by herpesvirus by "an exquisite adaptation of the viral genome is a promoter sequence that recognizes STAT6 as well as the prevailing TH2 environment of a helminth-infected host".

In other words, the virus has evolved an 'exquisite' mechanism for recognising and responding to the body's defensive response to infection by another unrelated parasite. Exquisite from the point of view of someone who recognises the exquisite in nature; a malevolent mechanism to anyone who tries to see it in terms of good and evil; an incomprehensible mechanism to someone who tries to force-fit it into a model with a single, omnibenevolent, philanthropic designer. As the authors say:

The findings of Reese et al. and Osborne et al. deepen our perspective of the complexity of infectious diseases, given that multiple colonization is ubiquitous in nature and the interactions between pathogens, commensals, and immunity operate at every level, from genes to tissues and systemic cell populations.


The first paper, by Reese et al., explains how infection by helminths can reactivate herpesviruses including the one associated with Kaposi’s sarcoma because "viral promoters that have evolved to sense host immune status":

Abstract*
Mammals are coinfected by multiple pathogens that interact through unknown mechanisms. We found that helminth infection, characterized by the induction of the cytokine interleukin-4 (IL-4) and the activation of the transcription factor Stat6, reactivated murine γ-herpesvirus infection in vivo. IL-4 promoted viral replication and blocked the antiviral effects of interferon-γ (IFNγ) by inducing Stat6 binding to the promoter for an important viral transcriptional transactivator. IL-4 also reactivated human Kaposi’s sarcoma–associated herpesvirus from latency in cultured cells. Exogenous IL-4 plus blockade of IFNγ reactivated latent murine γ-herpesvirus infection in vivo, suggesting a "two-signal model for viral reactivation. Thus, chronic herpesvirus infection, a component of the mammalian virome, is regulated by the counterpoised actions of multiple cytokines on viral promoters that have evolved to sense host immune status.


The second paper, by Lisa C. Osborne et al., shows how parasitic worms in the intestine interact with the resident bacteria and viruses normally found there.

Abstract
The mammalian intestine is colonized by beneficial commensal bacteria and is a site of infection by pathogens, including helminth parasites. Helminths induce potent immunomodulatory effects, but whether these effects are mediated by direct regulation of host immunity or indirectly through eliciting changes in the microbiota is unknown. We tested this in the context of virus-helminth coinfection. Helminth coinfection resulted in impaired antiviral immunity and was associated with changes in the microbiota and STAT6-dependent helminth-induced alternative activation of macrophages. Notably, helminth-induced impairment of antiviral immunity was evident in germ-free mice, but neutralization of Ym1, a chitinase-like molecule that is associated with alternatively activated macrophages, could partially restore antiviral immunity. These data indicate that helminth-induced immunomodulation occurs independently of changes in the microbiota but is dependent on Ym1.


In evolutionary terms, exquisite and delightful though these evolved mechanisms might be, they are entirely unsurprising and are even predictable. Since each mechanism promotes the survival and replication of the genes which promote it, and with no regard for the effects this might have on the host provided it doesn't actually kill the host too quickly, this is precisely what we would expect of 'selfish' genes being favoured by natural selection, if this produces more copies in future generations.

It is totally incomprehensible as the product of intelligent, planned design by a philanthropic, benevolent designer, however. No such designer would design parasites in the first place, then design a system for fighting them, then to design other parasites to exploit that system whilst redesigning the original parasite to overcome the host's resistance. To do anything resembling such a thing intentionally would be the very antithesis of benevolence. Perhaps, and I accept that this is probably a forlorn hope because it requires creationists to examine their assumptions and contemplate the possibility of being wrong, a creationist can explain how exactly this fits in with their 'Intelligent Design' form of biblical literalism, complete with a magic designer who does everything because it loves us.

And please don't invoke the circular 'ineffable' argument where you define 'good' as whatever your hypothetical designer does, then claim it as evidence for a benevolent designer because it's 'good', regardless of the harm it actually does, whilst settling for an unexplained mystery as your best explanation. Remember, you have to come up with something at least as complete as the current scientific explanation, together with supporting evidence, not just something different. Simply defining something that makes people sick and die betrays your moral bankruptcy and shows how you've abandoned any moral responsibility for your beliefs and actions.

* Copyright © 2014, American Association for the Advancement of Science


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5 comments :

  1. Talking of parasites, creationists have proposed many explanations in an attempt to make parasites compatible with a loving and benevolent God.

    Check out this link: http://www.johnjanovy.com/tapeworms.pdf
    It contains an excerpt of 4 pages from an ID-friendly book (?) called INTELLIGENT DESIGNER: EVOLUTION FOR POLITICIANS.

    Here are some quotes from the article mentioned above:

    1) So what was God thinking when He made tapeworms? The first and most logical answer to this question is: God wanted some device for keeping some of his most intelligent, curious, insightful, and creative humans occupied for their entire lives. He knew, because He was God, that intelligent, curious, insightful, and creative humans come up with all kinds of blasphemous thoughts, and furthermore, are not always big fans of organized religion. So He needed a way to
    involve these minds in some activity that prevented their intelligence and creativity from being applied to other activities such as war, especially war conducted in His name. We have some historical precedence for assuming that God made things to fool humans into harmless behaviors, perhaps the best ones being fossils, which keep lots of people occupied, for example,

    2) It is probably a pretty good bet that God’s intent and purpose for making
    tapeworms was the same as His intent and purpose for making all the rest of nature that we currently know about, or whose existence we can easily infer from what we do know, namely, as a source of truly great mystery and wonder.

    3) Our observations could then be consistent with some theological conclusions about God’s personality, namely, that He’s a creative, ingenious, and loving entity who likes to play hide and seek.

    4) God could easily have made tapeworms simply for His own pleasure.

    5) [Is the existence of parasites caused by laziness or ignorance by the Creator?] In this particular case, instead of laziness and ignorance, decidedly human traits, God might have been up to His eyebrows in administrative tasks and simply didn’t have time to check whether there were tapeworms in the beasts he was copying for Earth [from other planets there He alsp had created life and different life forms].

    YEAH! All five arguments listed in the quotes above are really strong ones. Or...? Seriously speaking: Have you ever seen such silly arguments? Maybe this paper was written by a seven years old schoolboy? And in that case, he's at least good at spelling.

    ReplyDelete
    Replies
    1. Must be nice to be a religious apologist. You just get to make stuff up and declare it to be true. No need to bother with evidence or sources or verification. Let there be a good reason for parasites and voilá! there is a good reason for parasites, just as William Lane Craig can declare genocide and infanticide to be good things - must be good because God did it.

      But the point they always gloss over is that parasitism, by definition, harms the host and harming the host is not the act of an omnibenevolent being.

      Delete
  2. Rosa, you missed the obvious humour. Parasites and Creationists - but I repeat myself. Boom Boom!

    ReplyDelete
  3. I just read this article: http://www.the-scientist.com//?articles.view/articleNo/40770/title/Interspecies-RNA-Shuffle/ . The headline is: "Interspecies RNA Shuffle", which is a relatively new and exciting topic in plant biology. The movement and functions of mobile RNAs in plants and between plants definitely extend the frontiers of possibilities to plant-plant interactions. (In that respect God seemingly was a clever Creator.)

    But here are some quotes from the article that makes me wonder how God, the Creator, could have thought in order to decide to make those things possible:

    1) “We’ve known for a while that parasitic plants take up a lot of nutrients, [and macromolecules] from host plants but what this paper shows is the real extent to which this happens. Upwards of one percent of the RNA transcripts in the parasite are from the host and vice versa and that is really dramatic,” said John Yoder...

    2) RNAs are used for regulating communication between the different tissues within a plant, “like sending a letter through the plant to a specific address,” said Westwood. “We thought there would be a similar spectrum of RNAs used for the parasite-host communication going on through the plants’ vascular systems. But instead, we found a whole cross section of RNAs suggesting that the parasitic relationship is something quite different from the normal cell-cell plant interaction.”

    3) The passive transport of RNAs as the parasite takes up materials from its host is a plausible explanation for the transfer. But, the reverse flow—from the parasitic plant to the host—is harder to explain, wrote Neelima Sinha, who studies genomic adaptations of plants at the University of California, Davis and was not involved in the work, in an e-mail to The Scientist. “The bi-directionality argues for an active, regulated process, and that is very interesting.”

    4) The bi-directional RNA movement also provides a novel mechanism for horizontal gene transfer and for the transfer of genes between plants, according to Yoder. “This means that the parasite can act as a bridge, facilitating movement of genetic material between unrelated, non-parasitic plants.”

    In other words: Our caring and amiable God seems to like parasites very much. Why else would He create this mechanism of a two-way (bilateral) transfer of RNA, at least between parasite and host in the world of plants? In my eyes that's more a sign of Unintelligent Design, increasing the chances for parasites to survive. That's why I believe God loves parasites.

    ReplyDelete
    Replies
    1. Helmer.

      You should be writing your own blog where you can expand on posts such as this. It would be well worth subscribing to.

      Delete

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