The Discovery Institute has posted an essay by a new contributor, Dr. Ann Gauger of the Biologic Institute.
If you are wondering whether this new expository source will sustain the Discovery Institute’s longstanding reputation for publishing spin, please read the following excerpts and be comforted.
Let me explain what the four forces are, and then I will describe the problem they pose.
Natural selection is the evolutionary force with which most people are familiar, and can be simply stated as follows: organisms better adapted to their environment tend to survive and have more offspring than other less fit counterparts, all other things being equal. Mutation and recombination act as the engine of organismal variation: mutations change an organism’s DNA (by substitution, insertion or deletion of particular bases, or modification of the DNA), while recombination shuffles the DNA into new combinations, thus producing further variation. This means that each individual has a unique genome. Differences in each individual’s DNA can produce differences in how well the organism functions in its environment. Finally, genetic drift causes particular variations to be lost from small populations at random, simply because individuals may die or fail to reproduce for reasons unrelated to their fitness for their environment.
This may seem counter-intuitive, so let me reiterate this point. Because of the accidental effects of genetic drift in small populations, natural selection is not strong enough to guarantee that beneficial mutations will eventually become fixed (universal) in a population or that weakly harmful mutations will be eliminated. Thus, in organisms with small effective population size (e.g. all vertebrates, which includes us humans), the stochastic and non-adaptive forces of mutation, recombination, and drift will tend to drive evolution in non-adaptive directions.
This picture of evolution is strikingly in contrast to the stories told by biologists who believe in the adaptive power of natural selection to generate whole new cellular systems, behaviors, and body plans (see for example Endless Forms Most Beautiful by Sean Carroll 3 or most evolutionary psychology arguments 4). If three out of the four forces driving evolution are non-adaptive, then perhaps most evolutionary change is also non-adaptive, and not due to the power of natural selection. Hence the controversy.
First, the main bit of illogic in the above. The conclusion, highlighted in the quoted excerpts, does not follow. The conclusion would need measurement of the relative frequencies of each process, something that Gauger apparently is not prepared to enter upon, since it would also invalidate her argument. Simply because there are four enumerated processes does not imply that some specific one of them must therefore occur less frequently, making the above quoted bit a straightforward piece of misleading and fallacious argumentation.
Second, another bit of illogic in the above. Gauger depends on a contributing argument, that if most evolutionary change is non-adaptive, adaptive processes cannot be said to account for such things as the generation of new cellular systems, behaviors, or body plans. This argument is completely unsupported by Gauger. Something Gauger fails to take cognizance of is that even among those called “adaptationist” as if it were an epithet, the prevalence of non-adaptive evolutionary change is commonly stipulated. I heard Richard Dawkins field a question as to whether natural selection could be said to be the main process in evolutionary change, and in his response he explicitly stated that when one looks at the level of proteins and the genome, what one mainly sees is change via genetic drift, but that if one looks at the level of visible or discernible morphological and behavioral traits, most of those have been shaped by selection. A trivial result from examination of the genetic code is that about 20% of possible single nucleotide changes are completely neutral, meaning that a substantial proportion of a genome could change without engaging any selection at all. On the other hand, only about 1.5% of the human genome codes for proteins. Selective processes can be far less frequently in action than drift and yet have important effects on the evolution of traits; what the mode of evolution is does not eliminate selection as the cause of the various phenomena Gauger lists.
Third, Gauger pushes innumeracies. When saying that “natural selection is not strong enough” to effect change, Gauger ignores the fact that one can utilize the math to determine just how strong selection would need to be to be effective at a given effective population size. There is no single fixed value for the strength of selective pressure on a particular trait, as Gauger’s text misleadingly relies upon; that is a context-dependent value that one can only get from empirical study. Certainly, only larger selective values will overcome drift at small population sizes, but one can then work on characterizing the likelihood that such strong selection may occur rather than following Gauger’s fallacy and believing that one need not even look. Another innumeracy of Gauger’s is her bland assertion that all vertebrates have small effective population sizes. This will come as a shock to ichthyologists, rodent biologists, and bat biologists everywhere. Even artiodactyls have had large effective population sizes (e.g., bison in North America before 1865). Once the various sorts of biologists are over their shock, though, they will have a good chuckle at Gauger’s expense.
Editor’s Note: Ann Gauger is a senior research scientist at Biologic Institute. Her work uses molecular genetics and genomic engineering to study the origin, organization and operation of metabolic pathways. She received a BS in biology from MIT, and a PhD in developmental biology from the University of Washington, where she studied cell adhesion molecules involved in Drosophila embryogenesis. As a post-doctoral fellow in the Department of Molecular and Cellular Biology at Harvard, she cloned and characterized the Drosophila kinesin light chain. Her research has been published in Nature, Development, and the Journal of Biological Chemistry. Her awards include a National Science Foundation pre-doctoral fellowship and an American Cancer Society post-doctoral fellowship.
That’s very sad. Gauger shouldn’t be having these very, very basic problems with the biology. It just goes to show just how ideological precommitment to “intelligent design” creationism can make even smart people like Gauger say uninformed things.<= get_option(\'vc_tag\') ?>> = get_option(\'vc_text_before\') ?> 40247 = get_option(\'vc_human_count_text_many\') ?> = get_option(\'vc_preposition\') ?> 12032 = get_option(\'vc_human_viewers_text_many\') ?> = get_option(\'vc_tag\') ?>>