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Running On Immunity Against Disproof


Three months ago Princeton evolutionary biologist Andrea Graham became the talk of the ecoimmunology town through her summarization of the apparent connection between immunity and fertility (1). From trials carried out on 1476 individuals of wild Soay sheep from the St Kilda island archipelago in northern Scotland, Graham et al painted a complex picture of competing trade-offs the strengths of which were intimately dependent on the prevalence of environmental extremes. They found that higher immunity amongst animals, while promoting better survival, negatively affected reproductive prowess (1,2). More specifically sheep with increased immune readiness against ‘parasite infested winters’ were less likely to sire offspring, which Graham et al attributed to the concomitantly higher levels of auto-reactive antibodies (1,2).

Low immune-response animals fared better in low ‘parasite prevalence’ environments perhaps because energy for reproduction was not frivoled away on energy-costly antibody manufacture (1,2). The conclusion drawn was that the selective advantage of low immune-and high-immune response animals in low parasite prevalence and high parasite prevalence environments respectively explains why evolution has in effect “failed to eliminate alleles that confer susceptibility to infection or promote autoimmunity”(2).

So can we pack our bags and head home content with yet another open-and-shut case in which natural selection has been incontrovertibly authenticated? Not quite. The work of Graham et al also brought into view a nagging theoretical belly-ache for evolutionists by demonstrating natural selection to be, as prominent anti-Darwinist Phillip Johnson once quipped “an all-purpose explanation which can account for anything, and which therefore explains nothing” (3). In his book Darwin On Trial Johnson underscored the idea, most commonly attributed to the philosopher Karl Popper, that just about any characteristic can be deemed to be disadvantageous or advantageous depending on the surrounding environmental conditions (3). The above example makes this plain. One cannot make a case for the propagation of detrimental immunity genes without first knowing what climatic and parasitic sways have possibly influenced the eventuality. Johnson’s own choice example brought this point home:

“It may seem obvious that it is advantageous for a wild stallion to be able to run faster, but in the Darwinian sense this will be true only to the extent that a faster stallion sires more offspring. If greater speed leads to more frequent falls, or if faster stallions tend to outdistance the mares and miss opportunities for reproduction, then the improvement may be disadvantageous” (3)

Johnson further noted how in such cases “it is impossible to identify the advantage independently of the outcome” (3). Since advantages are not readily identifiable ahead of time, not much is excludable. The goal posts of permissibility are kept wide enough so that just about any outcome is admissible. In the Soay sheep study the author’s closing inference- that “a complex and potentially balancing set of associations in a variable environment suggest a mechanism for the maintenance of immunoheterogeneity” proved to be about as uninformative and open-ended a statement as one might find in life science circles. Simply put, heterogeneity begets heterogeneity.

Pennsylvania State University evolutionary biologist Andrew Read remarked that ecoimmunology, which looks at the interplay between ecological factors and immune response “has been a controversial field because it’s really hard to decide what to measure without a history [of the population]” (1). For the Soay sheep on St. Kilda, the history was well known: “longitudinal information on both individual life histories and population dynamics” had been available since as long ago as 1985 (2). But truth be told, even if such histories were not readily available Darwinists have freed themselves from the need to predict what natural selection will or will not do in the future by “adjusting the theory as necessary to conform to the observed facts” (3). Writing on the philosophical necessity of Darwinism, Johnson added that “the adjusting devices are so flexible that in combination they make it difficult to conceive of a way to test the claims of Darwinism empirically” (3). In short, Darwinism is immune to disproof.

It would appear that some exobiologists have learnt a lesson or two from their evolutionist brethren. In a NewScientist piece on the telltale chemistry of life last week, NASA’s Chris McKay speculated that the relative abundances of life-signature chemicals might be all the indicatory evidence we need to home in on potential life-berthing planets (4). Christoph Adami, who garnered notoriety as co-designer of the evolutionary algorithm AVIDA, has compared amino acid levels from earth’s soils and oceans with those of abiotic sources and found that, while terrestrial/biotic samples were rich in more complex amino acids, the simpler Alanine and Glycine residues dominated the abiotic fingerprint (4). Not much of a surprise there. Adami then decided to put his AVIDA brainchild through its paces by ‘evolving’ populations of Avidians as a way of showing that chemical ‘signatures’ are a reality of any life-sustaining habitat including those in the digital realm (4,5).

Yet accompanying this ‘universal principle’ (term chosen by Adami) was a disclaimer that would conveniently allow any budding exobiologist to eschew the clutches of maligning critics lest extra-terrestrial life were never found. Washington State University’s Dirk Schulze-Makuch led the disclamatory charge by maintaining that “different minerals, temperatures and pressures could allow for chemical reactions that do not occur on Earth” and might therefore be difficult to pull out from the hubbub of non-biotic reactions (4). The announcement (contentious at that) of arsenic-backboned DNA in one bacterial strain (6) has also been pounced on to fuel speculation that life outside of our fuzzy warm planet may truly be “not as we know it” (7,8). That there is life outside our planet is not in doubt, inevitabilists assure us (9). These same protagonists of the universality of life would have us believe that we simply have not had sufficient time to search alternative exotic life-fostering chemistries (7,8). Immunity from disproof is as present in this sort of reasoning as it is in Darwinist ideology. After all, one can interminably argue for what is not there if one unwaveringly assumes that it is hidden from view.

Further Reading
1. Vanessa Schipani (2011) Strong immunity=low fertility, The Scientist, October 28th.
2. Graham et al (2010) Fitness Correlates of Heritable Variation in Antibody Responsiveness in a Wild Mammal, Science, Volume 330 pp.662-65.
3. Phillip Johnson (1991), Darwin on Trial, 1st Ed, InterVarsity Press Publishers, Madison, Wisconsin, pp. 20-30
4. Michael Marshall (2011) Telltale chemistry could betray ET, NewScientist, 21st January, 2011,
5. Evan D. Dorn, Kenneth H. Nealson and Christoph Adami (2011) Monomer Abundance Distribution Patterns as a Universal Biosignature: Examples from Terrestrial and Digital Life, Journal of Molecular Evolution, DOI: 10.1007/s00239-011-9429-4
6. Felisa Wolfe-Simon et al (2010) A Bacterium That Can Grow by Using Arsenic Instead of Phosphorus, Science, Published online 2 December 2010 [DOI:10.1126/science.1197258]
7. Seth Shostak (2010) Life But Not As We Know It, The Huffington Post, December 5th, 2010
8. Richard Alleyne ‘Life as we don’t know it’ discovery could prove existence of aliens, The Daily Telegraph, 1st December, 2010
9. Inevitabilists believe that the origins of life is truly an inevitable consequence of some fundamental natural tendency in the universe towards great complexity, See Improbabilists, Inevitabilists And The Astonishing Mystery Of Life


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