New Chromosome Research Undermines Human-Chimp Similarity Claims.
by Jeffrey Tomkins, Ph.D., & Brian Thomas, M.S. A recent high-profile article in the journal Nature released the results of a study with implications that shocked the scientific community because they contradict long-held claims of human-chimp DNA similarity.
A previous Acts & Facts article showed that much of the research surrounding the often touted claims of 98 percent (or higher) DNA similarity between chimps and humans has been based on flawed and biased research.
The problem is that the similarity has been uncertain because no one has performed an unbiased and comprehensive DNA similarity study until now. And the results are not good news for the story of human evolution.
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In the 2005 chimpanzee genome project and resulting Nature journal publication, the sequence contigs were not assembled and oriented based on a map of the chimpanzee genome, but rather on a map of the human genome. Given the fact that the chimpanzee genome is at least 10 percent larger overall than the human genome, this method of assembly was not only biased toward an evolutionary presupposition of human-chimp similarity, but was also inherently flawed.
The title of the recent journal article accurately sums up the research findings: "Chimpanzee and Human Y Chromosomes are Remarkably Divergent in Structure and Gene Content." Before getting into the details of their results, it is important to understand that for the first time, the chimpanzee DNA sequence for a chromosome was assembled and oriented based on a Y chromosome map/framework built for chimpanzee and not human. As a result, the chimpanzee DNA sequence could then be more accurately compared to the human Y chromosome because it was standing on its own merit.
Not only were the locations of DNA categories completely different between human and chimp, but so were their proportions. One sequence class, or category containing DNA with a characteristic sequence, within the chimpanzee Y chromosome had less than 10 percent similarity with the same class in the human Y chromosome, and vice versa. Another large class shared only half the similarities of the other species, and vice versa. One differed by as much as 3.3-fold (330 percent), and a class specific to human "has no counterpart in the chimpanzee MSY [male-specific Y chromosome]."
As far as looking at specific genes, the chimp and human Y chromosomes had a dramatic difference in gene content of 53 percent. In other words, the chimp was lacking approximately half of the genes found on a human Y chromosome. Because genes occur in families or similarity categories, the researchers also sought to determine if there was any difference in actual gene categories. They found a shocking 33 percent difference. The human Y chromosome contains a third more gene categories--entirely different classes of genes--compared to chimps.
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So, the human Y chromosome looks just as different from a chimp as the other human chromosomes do from a chicken. And to explain where all these differences between humans and chimps came from, believers in big-picture evolution are forced to invent stories of major chromosomal rearrangements and rapid generation of vast amounts of many new genes, along with accompanying regulatory DNA.
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