Luskin v Tree of Life: More Troubles in the Tree of Animal Life? March 22, 2008 19:17 MST

Casey Luskin exposes some of his unfamiliarity with evolutionary theory when he claims that there are “More Troubles in the Tree of Animal Life”.

And how does Luskin reach this remarkable conclusion well because of our ignorance of science.

Casey Luskin wrote:

In late 2005, three biologists published a study in Science which concluded, “Despite the amount of data and breadth of taxa analyzed, relationships among most [animal] phyla remained unresolved.”

Luskin references an article in Science Daily titled Tree Of Animal Life Has Branches Rearranged, By Evolutionary Biologists to further his claims. So let’s explore Luskin’s misunderstandings and see what science does and does not know, lest one may get the impression that there is some fundamental flaw with the ‘Tree of Life’

Casey Luskin wrote:

In 2008, the relationships among animals are still controversial. A recent news release at Science Daily highlights a new study, “Tree Of Animal Life Has Branches Rearranged.” The story reports, “The study is the most comprehensive animal phylogenomic research project to date, involving 40 million base pairs of new DNA data taken from 29 animal species.”

Luskin focuses on the ‘surprising results’ while somehow avoiding the other findings of the study

The study, which appears in Nature, settles some long-standing debates about the relationships between major groups of animals and offers up a few surprises.

Luskin seems concerned about Science rearranging the root of the tree based on new findings. I have observed that it is quite common amongst creationists to see Science’s ability and flexibility to deal with new data, as a weakness of science. To a creationist, the Truth has already been established.

Casey Luskin wrote:

According to the article, the study yielded surprising results: “Comb jellyfish – common and extremely fragile jellies with well-developed tissues – appear to have diverged from other animals even before the lowly sponge, which has no tissue to speak of. This finding calls into question the very root of the animal tree of life, which traditionally placed sponges at the base.”

However Dunn, one of the authors of the paper in question, which was published in Nature, points out that the study has found some fascinating verifications as well as new insights into the evolution of life.

Dunn and his team: * unambiguously confirmed certain animal relationships, including the existence of a group that includes invertebrates that shed their skin, such as arthropods and nematodes; * convincingly resolved conflicting evidence surrounding other relationships, such as the close relationship of millipedes and centipedes to spiders rather than insects; * established new animal relationships, such as the close ties between nemerteans, or ribbon worms, and brachiopods, or two-shelled invertebrates. “What is exciting is that this new information changes our basic understanding about the natural world – information found in basic biology books and natural history posters,” Dunn said. “While the picture of the tree of life is far from complete after this study, it is clearer. And these new results show that these new genomic approaches will be able to resolve at least some problems that have been previously intractable.”

Source: Casey W. Dunn et al Broad phylogenomic sampling improves resolution of the animal tree of life, Nature (Full Text

The paper ends with the following comment

The placement of ctenophores (comb jellies) as the sister group to all other sampled metazoans is strongly supported in all our analyses. This result, which has not been postulated before, should be viewed as provisional until more data are considered from placozoans and additional sponges. If corroborated by further analyses, it would have major implications for early animal evolution, indicating either that sponges have been greatly simplified or that the complex morphology of ctenophores has arisen independently from that of other metazoans. Independent analyses of ribosomal and non-ribosomal proteins (Supplementary Information and Supplementary Fig. 10) indicate that support for this hypothesis (and for others presented for the first time here, such as Clade A and Clade B) is much greater in the combined analyses than in partitioned analyses with fewer genes. This may explain why these novel clades have not been recovered before, because support requires very broad gene sampling.

Compare this with Luskin’s description

This is the common theme among systematists trying to produce a grand “tree of life”: Similarities between different types of organisms commonly pop up in places they shouldn’t. Such unexpected similarities were found in this study, forcing one of the scientists to conclude “either that comb jellies evolved their complexity independently from other animals, [or] sponges have become greatly simplified through the course of evolution.”

Unexpected does not mean wrong, just that new data resolves some of the details. First of all, the data needs to be confirmed but furthermore, it has opened up evolutionary theory to more exciting hypotheses that will further new research.

What has Intelligent Design to offer here? Luskin does not explain, other than a strange story about Atlantis and a conclusion that “The other possibility is that there is no Atlantis to find and that people are mistaken in their various theories about how to find Atlantis.”

Atlantis has never been found, the Tree of Life, while well resolved at some aspects, needs more work to figure out the details in the evolutionary history of the millions of species involved.

For those interested in reading more about the this see for instance 29+ Evidences for Macroevolution by Douglas Theobald, Ph.D. (a little dated)

As to why morphological and genetic trees can and do conflict, see for instance Molecular versus Morphological Data in Systematic Studies

Now let me be the first one to point out that much of the Tree of Life remains unknown, although some important aspects have been successfully resolved. Does this mean that additional data is not going to add or overturn parts of the TOL? Of course not, what ID sees as a weakness of evolutionary theory and science is general is how science iterates between data, hypotheses, more data, some hypotheses rejected, more hypotheses and so on, towards an ever increasing understanding of how life evolved.