by Jeffrey Tomkins and Jerry Bergman
A major argument for human evolution from a shared common ancestor with the great apes, particularly chimpanzees, is the ‘chromosome 2 fusion model’. This molecular model involves the hypothetical fusion of two small acrocentric chimpanzee-like chromosomes (2A and 2B) at some ancient point in the human evolutionary lineage. Our analysis of the available genomic data shows that the sequence features encompassing the purported chromosome 2 fusion site are too ambiguous to accurately infer a fusion event. The data actually suggest that the core ~800 bp region containing the fusion site is not a unique cryptic and degenerate head-to-head fusion of telomeres, but a distinct motif that is represented throughout the human genome with no orthologous counterpart in the chimpanzee genome on either chromosome 2A or 2B. The DNA sequence evidence for a purported inactivated cryptic centromere site on chromosome 2, supposedly composed of centromeric alphoid repeats, is even more ambiguous and untenable than the case for a fusion site. The alphoid sequences in this region are quite variable and do not cluster with known functional human centromeric sequences. In addition, no ortholog for a cryptic centromere homologous to the alphoid sequence at human chromosome 2 exists on chimpanzee chromosomes 2A and 2B.
One of the most cited DNA-based arguments for human evolution is the hypothetical head-to-head fusion of two small ape-like chromosomes to form human chromosome 2.1 The corresponding chromosomes supposedly represented in the great apes are 2A and 2B in the chimpanzee genome. A majority of the research that undergirds this model utilized indirect methods of DNA analysis. These data were derived from DNA probe hybridization, chromosomal banding (staining), and limited DNA sequencing techniques that were available prior to the advent of high-throughput DNA sequencing technology.1,2
Chromosome staining and hybridization techniques do not provide detailed DNA sequence information, but rather indicate putative areas of homology. Chromosome staining used to achieve visible banding markers yields information related to GC base content, repeat content, CpG island density, and degree of condensation over large areas rather than specific sequence homology.3,4 Probe (DNA) hybridization is a more direct and accurate method for detecting DNA homology, but is subject to lab protocol variability and does not provide actual DNA sequences. Early DNA sequencing projects were largely limited to small, isolated regions of eukaryote genomes, a scenario that changed with the introduction of large-insert DNA cloning (bacterial artificial chromosomes; BACs) and BAC contig-based physical mapping strategies….
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