This post is the second part of a three-post series aimed at clearing up the misinformation written by the Discovery Institute’s Casey Luskin. In his recent posts, Luskin tries to persuade his readers that the idea of a tree of life (TOL) and the very idea of phylogenetic trees is erroneous and not evidence of common descent. These trees are created by looking at genetic similarities between organisms to arrange them in terms of relatedness and common ancestry. In my series of posts, I will expose the weaknesses in the arguments put forth by Luskin.
Part 2 – Analysis and rebuttal
One of Luskin’s points in his post is to question the motives and biases of scientists. Here, Casey Luskin claims that scientists assume there is a tree of life so their findings will support their preconceived notions:
the first assumption that goes into tree-building is the basic assumption that similarity between different organisms is the result of inheritance from a common ancestor
Of course this is a ridiculous proposition. I guess Luskin has completely forgotten all about Charles Darwin and all the study into evolution since that time. Prior to Darwin, common ancestry was not an idea that had any credence. Sine the time of Darwin, more and more evidence keeps adding to Darwin’s idea basic ideas of common descent. Basing ideas on evidence is not the same thing as assuming.
Luskin also contents that scientists engage in ad hoc reasoning:
whenever data contradicts expectations of common descent, evolutionists resort to a variety of different ad hoc rationalizations to save common descent from being falsified
No. What scientists do is to take this new information and form new hypothesis and alter the details of evolution. Science is always changing. Finding unexpected things is what makes science interesting and nothing is gained in science by keeping ideas that have been proven wrong.
As far as saving “common descent from being falsified,” evolution is easily falsifiable. Find a rabbit in the precambrian and all of evolution will fall apart. Find genes in humans that more resemble cockroach genes than any mammal. However, one result like this would need to be critically analyzed to go against years of research and thousands of experiments.
I find it hilarious that he uses the idea of “ad hoc reasoning” to criticize evolution. The whole idea of intelligent design (ID) is ad hoc reasoning. Any result or any piece of data can be simply said to have been designed that way. There are no predictions or testable hypothesis in ID.
In his second post, Luskin draws heavily on the false idea that scientists are abandoning the tree of life. A lot of his all comes from the dreaded New Scientist article, “Darwin was wrong.” I am not going to go into the details as many others have shown that the article was inaccurate to say the least here, here, here , and here.
In addition to heavily quoting the New Scientist article, Luskin “quote mines” from several different scientific papers. One of the more egregious examples comes from a 2005 science paper by Rokas et al. Luskin says:
Other scientists agree with the conclusions of the New Scientist article. Looking higher up the tree, a recent study published in Science tried to construct a phylogeny of animal relationships but concluded that “[d]espite the amount of data and breadth of taxa analyzed, relationships among most [animal] phyla remained unresolved.”
Luskin neglects to mention that the next couple sentences:
In contrast, the same genes robustly resolved phylogenetic relationships within a major clade of Fungi of approximately the same age as the Metazoa. The differences in resolution within the two kingdoms suggest that the early history of metazoans was a radiation compressed in time, a finding that is in agreement with paleontological inferences.
Luskin fails to mention a few critical points in the article. He ignores the fact that a well constructed tree based on Fungi can be made. Also missing is the fact that the authors came up with a hypothesis to explain the previous data. Finally, Luskin fails to mention that the authors provide for a better way to look create phylogenetic trees when problems arise, rare genomic changes.
Luskin continues the quote mining throughout the post, but he never really says anything favors an intelligent design perspective. He is just using the tried and true method of ID proponents, namely to find the currently unresolved issues in the scientific literature and omit the overwhelming number of successful findings.