The new flu shows big evolutionary changes can occur virtually overnight.
The influenza virus recently in the news -- first known as a "swine flu" then rebadged as H1N1 2009 to better identify it with comparison H1N1 influenzas and to protect hog farmers and the hogs themselves from public backlash -- represents a change (i.e., a mutation) that is not the kind of point-mutation "accident" most commonly understood to create change in a genome over time. Known as "reassortment", the trick that combined genetic material from several different influenza strains -- strains with known origins in three different host species, namely human, swine, and avian -- enables a strain in one step to take on genetic material with a proven track record developed in an entirely different virus population. Instead of changing one base pair at a time -- which may allow slow drift of a genome, or may simply produce a dead-end that doesn't work -- this process enables huge genetic changes in a single generation.
These dramatic changes can mean improved avoidance of host population defenses built up against predecessor agents of infection. Reassortment has thus been identified as a factor in major epidemics -- that is, sudden population-level problems coping with the dominant virus strain, and the replacement of the dominant virus strain with a successor -- over the last century.
The existence of sudden mechanisms of significant genetic alteration offers some interesting food for thought as we consider periods of time in which our planet has experienced an apparently accelerated speciation. New species, perhaps more resistant to prevailing illnesses or more capable of competing for food, might displace existing species with relative speed. New pathogens might crush longstanding species' public-health-free populations, creating opportunities for creatures that could not compete until hardiness from new illnesses became a competitive advantage. Collapse of certain species might have ripple effects across an environment, creating new opportunities for naescent competitors.
Debates will doubtless continue over just how major population collapses occurred, or the reasoning behind major speciation events. It is certain that argument will continue over even the existence of speciation through the mechanism of evolution. (Interestingly, however, I have not yet heard any alternate theory to explain speciation. Presumably -- if non-evolutionary theory is to be accepted -- there is every so often another Creation, isolated so one or isolated parts of the globe, to produce whatever new species might emerge there. I haven't seen any particular evidence gathered for this kind of claim; much less, I haven't even heard the apparently-necessary claim.)
Reassortment, or other mechanisms such as transposons that enable single-step alterations much greater in scope than mere point mutations, and can even allow cross-species importation of survival-proven genetic material, absolutely torpedo the claim of Mr. Berlinski -- that the theory of evolution "requires for every significant morphological or physiological feature in a modern species ... a panoply of intermediate forms that explains how they arrived." Since massive single-generation genetic changes would not leave a "panoply of intermediate forms" there is no reason to expect such a "panoply of intermediate forms[.]" Such a presentation of "intermediate forms" would not explain how they arrived, they would only illustrate one possible effect of a series of related point mutations. When mutation mechanisms other than simple point mutations are considered, it's obvious that Mr. Berlinski's argument is bankrupt, and capable only of fooling those who have no idea what kinds of mechanisms might underlie mutation.
The important thing is that we continue to collect and evaluate evidence -- without which we have little hope of understanding the rules that govern the world around us. Why the rules are as they are is of course a matter of faith, and philosophy. However, I have grave doubts about any system of belief that requires people to turn a blind eye to the evidence available in the world about them. If humans live with some purpose, surely this purpose does not require each member of the species to shrink from having a close look at the world about. Particularly if from the earliest record we were called upon before all other tasks to give a name to all the species, then to cultivate the place where we were delivered to live, we should be making some non-trivial effort to understand what the species are so they can be named, and to learn what might be learned about the cultivation of the resources entrusted to us so that we may do a competent job of it.
Falling to bickering over why there are species seems backward when we have yet to understand fully how they are made and what the result has been -- both of which would presumably be a source of insight into that why question, evidencing its answer like little else.
No comments:
Post a Comment