Darwin's Tree of Life is a Tangled Bramble Bush
Researchers at Vanderbilt University are tied up in knots trying to locate Darwin’s branching tree in contradictory data.
A press release from Vanderbilt University summarizes a paper in Nature this week:
These days, phylogeneticists – experts who painstakingly map the complex branches of the tree of life – suffer from an embarrassment of riches. The genomics revolution has given them mountains of DNA data that they can sift through to reconstruct the evolutionary history that connects all living beings. But the unprecedented quantity has also caused a serious problem: The trees produced by a number of well-supported studies have come to contradictory conclusions.
Salichos and Rokas, in their Nature paper, had to resort to postulating rapid periods of diversification and long periods of stasis to keep Darwin’s vision intact against the onslaught of data. The press release continues,
In a study published online May 8 by the journal Nature, Rokas and graduate student Leonidas Salichos analyze the reasons for these differences and propose a suite of novel techniques that can resolve the contradictions and provide greater accuracy in deciphering the deep branches of life’s tree….
“The study by Salichos and Rokas comes at a critical time when scientists are grappling with how best to detect the signature of evolutionary history from a deluge of genetic data. These authors provide intriguing insights into our standard analytical toolbox, and suggest it may be time to abandon some of our most trusted tools when it comes to the analysis of big data sets. This significant work will certainly challenge the community of evolutionary biologists to rethink how best to reconstruct phylogeny,” said Michael F. Whiting, program director of systematics and biodiversity science at the National Science Foundation, which funded the study.
Problem is, the data looks more like a bush than a tree. The record is punctuated by rapid, sudden appearances of organisms. The authors acknowledged the problem of the Cambrian explosion:
In broad terms, Rokas and Salichos found that genetic data is less reliable during periods of rapid radiation, when new species were formed rapidly. A case in point is the Cambrian explosion, the sudden appearance about 540 million years ago of a remarkable diversity of animal species, without apparent predecessors. Before about 580 million years ago, most organisms were very simple, consisting of single cells occasionally organized into colonies.
“A lot of the debate on the differences in the trees has been between studies concerning the ‘bushy’ branches that took place in these ‘radiations’,” Rokas said.
Calling this a “paradox,” the researchers found that even within yeast species a thousand genes did not match up to phylogenetic trees generated by standard software methods. The same conflicts were found in larger data sets involving vertebrates and metazoans. In response, they claimed that genetic dating becomes as unreliable as radiometric dating the farther back in time one searches, creating “considerable challenges to existing algorithms to resolve radiations” congruent with Darwin’s presumed ancestral tree.
One whole subsection in the paper is titled, “All gene trees differ from species phylogeny.” Another is titled, “Standard practices do not reduce incongruence.” A third, “Standard practices can mislead.” One of their major findings was “extensive conflict in certain internodes.”
The authors not only advised throwing out some standard practices of tree-building, but (amazingly) proposed evolutionists throw out the “uninformative” conflicting data and only use data that seems to support the Darwinian tree: “the subset of genes with strong phylogenetic signal is more informative than the full set of genes, suggesting that phylogenomic analyses using conditional combination approaches, rather than approaches based on total evidence, may be more powerful.”
In conclusion, they had no solid answers for the conflicts. They called on other evolutionists to “to develop novel phylogenomic approaches and markers to more accurately decipher the most challenging ancient branches of life’s genealogy from the DNA record.”
This is scandalous! It’s also old news. Evolutionists have been concocting Darwin trees in spite of the evidence ever since Darwin acknowledged the Cambrian explosion as a real problem that lodged a valid objection to his theory (get the new book Darwin’s Doubt for details, and the film Darwin’s Dilemma).
Darwinism is a classic case of Finagle’s Rule #3, “Draw your curves, then plot your data.” Guru Charlie drew his little tree sketch by faith, then sent his disciples out on a hopeless quest to find evidence to support it. Now, here it is May 15, 2013, and these guys are still telling us the tree vision is in conflict with the data! They have to finagle their methods (“novel approaches”) to try to force a match with the uncooperative genes.
And here, we saw they are even willing to lie, tossing out “uninformative” data sets and only using data that appear to support their foreordained conclusion. Were you told this in biology class? Did your textbook mention this? No; but you hear it here on CEH all the time, because we bring out into the open the dirty deals evolutionists whisper to themselves in the journals.
It’ll all work out. Just add more epicycles!