Wednesday, July 02, 2014

David MacMillan: Understanding creationism, VI: An insider’s guide by a former young-Earth creationist

Panda's Thumb has the sixth installment by David MacMillan on Understanding Creationism.  This one deals with the correspondence between fossil taxonomic studies and genetic evidence as well as the daunting task of constructing phylogenies.  He writes:
The more items you have in a given collection, the more ways they can be arranged. Just five items can be arranged in 120 different ways, and ten items can be arranged in a staggering 3.6 million ways. But the task of placing items into a branching tree is even more complex; for only five items, there are an unbelievable 6.6 × 10198 different possible branching trees. The number of possible trees for just five species is hundreds of orders of magnitude greater than the number of gene sequences that could be used to compare those five different species. So a researcher can’t simply “pick” the sequence that matches; there’s no chance of getting a match in any sequence unless there’s a real phylogeny to work with.

Most importantly, researchers don’t pick only a single sequence. Phylogenetic analysis is performed on many different sequences, and then all of the resulting trees are compared to each other to see which one appears most consistently. Trees produced by random noise will appear only once; accurate trees will appear in multiple sequences. All these clear facts are completely missing from the creationist understanding.
Read the whole thing, especially the response to the “common design” argument.

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