Problem 7: Convergent Evolution Challenges Darwinism and Destroys the Logic Behind Common Ancestry
Editor's note: This is Part 7 of a 10-part series based upon Casey Luskin's chapter, "The Top Ten Scientific Problems with Biological and Chemical Evolution," in the volume More than Myth, edited by Paul Brown and Robert Stackpole (Chartwell Press, 2014). The full chapter can be found online here. Other individual installments can be found here: Problem 1, Problem 2, Problem 3, Problem 4, Problem 5, Problem 6, Problem 8, Problem 9, Problem 10.
In Problem 6 of this series, we saw that the main assumption underlying all phylogenetic trees is that biological similarity is the result of inheritance from a common ancestor. The problem for evolutionary biologists faced with conflicting evolutionary trees is that biological similarity often appears in places not predicted by common descent. In other words, everyone recognizes that biological similarities often appear among species in cases where they cannot be explained as the result of inheritance from a common ancestor. This means the main assumption fails.
We also saw at the end of Problem 6 that when biologists are unable to construct phylogenetic trees, they often make ad hoc appeals to other processes to explain away data that won't fit a treelike pattern. One of these explanations is convergent evolution, where evolutionary biologists postulate that organisms acquire the same traits independently, in separate lineages, and not through inheritance from a common ancestor. Whenever evolutionary biologists are forced to appeal to convergent evolution, it reflects a breakdown in the main assumption, and an inability to fit the data to a treelike pattern. Examples of this abound in the literature, but a few will suffice.
Genetic Convergent Evolution
A paper in the Journal of Molecular Evolution found that molecule-based phylogenies conflicted sharply with previously established phylogenies of major mammal groups, concluding that this anomalous tree "is not due to a stochastic error, but is due to convergent or parallel evolution."119
A study in Proceedings of the U.S. National Academy of Sciences explains that when biologists tried to construct a phylogenetic tree for the major groups of birds using mitochondrial DNA (mtDNA), their results conflicted sharply with traditional notions of bird relationships. They even found "convergent" similarity between some bird mtDNA and the mtDNA of distant species such as snakes and lizards. The article suggests bird mtDNA underwent "multiple independent originations," with their study proposing "multiple independent origins for a particular mtDNA gene order among diverse birds."120
A 2005 paper in Nature Immunology observed that plants and animals have a highly similar biochemical organization of their respective innate immune systems, but their common ancestor didn't have such an immune system:
Although it seems to be generally accepted that the innate immune responses of plants and animals share at least some common evolutionary origins, examination of the available data fails to support that conclusion, despite similarities in the overall 'logic' of the innate immune response in diverse multicellular [organisms].121
According to the paper, common descent cannot explain these "unexpectedly similar" systems, "suggesting independent evolutionary origins in plants and animals." The paper is forced to conclude that such complex similarities make for a "compelling case for convergent evolution of innate immune pathways."122
Another famous example of convergent evolution is the ability of bats and whales to use echolocation, even though their distant common ancestor did not have this trait. Evolutionary biologists long-believed this was a case of morphological convergence, but an article in Current Biology explains the "surprising" finding that echolocation in bats and whales also involves genetic convergence:
Only microbats and toothed whales have acquired sophisticated echolocation, indispensable for their orientation and foraging. Although the bat and whale biosonars originated independently and differ substantially in many aspects, we here report the surprising finding that the bottlenose dolphin, a toothed whale, is clustered with microbats in the gene tree constructed using protein sequences encoded by the hearing gene Prestin.123
One paper called this data, "one of the best examples of convergent molecular evolution discovered to date."124 But again, these are hardly isolated examples. In 2010, a paper in Trends in Genetics explained:
The recent wide use of genetic and/or phylogenetic approaches has uncovered diverse examples of repeated evolution of adaptive traits including the multiple appearances of eyes, echolocation in bats and dolphins, pigmentation modifications in vertebrates, mimicry in butterflies for mutualistic interactions, convergence of some flower traits in plants, and multiple independent evolution of particular protein properties.125
Biochemist and Darwin-skeptic Fazale Rana reviewed the technical literature and documented over 100 reported cases of convergent genetic evolution.126 Each case shows an example where biological similarity -- even at the genetic level -- is not the result of inheritance from a common ancestor. So what does this do to the main assumption of tree-building that biological similarity implies inheritance from a common ancestor? With so many exceptions to the rule, one has to wonder if the rule itself holds merit.
The Earth is Round, But Is Common Ancestry True?
One evolutionary scientist tried to pressure his readers into accepting Darwinism by claiming "biologists today consider the common ancestry of all life a fact on par with the sphericity of the earth."127 But are such categorical statements even helpful, much less true?
Proponents of neo-Darwinian evolution are forced into reasoning that biological similarity implies common ancestry, except for when it doesn't. And in the many cases where it doesn't, they appeal to all sorts of ad hoc rationalizations to save common ancestry.
Tellingly, the one assumption rarely questioned is the overall assumption of common ancestry itself. But perhaps the reason why different genes are telling different evolutionary stories is because the genes have wholly different stories to tell, namely stories that indicate that all organisms are not genetically related. There is some hope for a different story more attuned to the data, as Michael Syvanen dared to suggest in Annual Review of Genetics in 2012, that "life might indeed have multiple origins."128 In other words, universal common ancestry may in fact, not be true.
[119.] Ying Cao, Axel Janke, Peter J. Waddell, Michael Westerman, Osamu Takenaka, Shigenori Murata, Norihiro Okada, Svante P��bo, Masami Hasegawa, "Conflict Among Individual Mitochondrial Proteins in Resolving the Phylogeny of Eutherian Orders," Journal of Molecular Evolution, 47 (1998): 307-322.
[120.] David P. Mindell, Michael D. Sorenson, and Derek E. Dimcheff, "Multiple independent origins of mitochondrial gene order in birds," Proceedings of the National Academy of Sciences USA, 95 (September, 1998): 10693-10697.
[121.] Frederick M Ausubel, "Are innate immune signaling pathways in plants and animals conserved?," Nature Immunology, 6 (10): 973-979 (October, 2005).
[123.] Ying Li, Zhen Liu, Peng Shi, and Jianzhi Zhang, "The hearing gene Prestin unites echolocating bats and whales," Current Biology, 20(2):R55-R56 (January, 2010) (internal citations removed);
[124.] Gareth Jones, "Molecular Evolution: Gene Convergence in Echolocating Mammals," Current Biology, 20(2):R62-R64 (January, 2010); Yong-Yi Shen, Lu Liang, Gui-Sheng Li, Robert W. Murphy, Ya-Ping Zhang, "Parallel Evolution of Auditory Genes for Echolocation in Bats and Toothed Whales," PLoS Genetics, 8 (6): e1002788 (June, 2012).
[125.] Pascal-Antoine Christin, Daniel M. Weinreich, and Guillaume Besnard, "Causes and evolutionary significance of genetic convergence," Trends in Genetics, 26(9):400-405 (2010) (internal citations omitted).
[126.] See Fazale Rana, The Cell's Design: How Chemistry Reveals the Creator's Artistry, pp. 207-214 (Baker Books, 2008).
[127.] Karl W. Giberson, Saving Darwin: How to be a Christian and Believe in Evolution, p. 53 (HarperOne, 2008).
[128.] Michael Syvanen, "Evolutionary Implications of Horizontal Gene Transfer," Annual Review of Genetics, 46:339-356 (2012).
Image by NASA/Apollo 17 crew; taken by either Harrison Schmitt or Ron Evans [Public domain], via Wikimedia Commons.