Now, to the point of the thread. The following recently conducted research seems to suggest that humans aren't as genetically similar to each other as previously thought.
http://www.sciencedaily.com/releases/20 ... 115741.htmGenetic Variation: We're More Different Than We Thought
New research shows that at least 10 percent of genes in the human population can vary in the number of copies of DNA sequences they contain--a finding that alters current thinking that the DNA of any two humans is 99.9 percent similar in content and identity.
In the freely available Database of Genomic Variants, each bar represents a chromosome in the human genome. Blue shows the genomic distribution of copy number variations on each chromosome. Green marks the location of all annotated duplications, and red represents inversions and inversion breakpoints. (Image Credit: Junjun Zhang)
This discovery of the extent of genetic variation, by Howard Hughes Medical Institute (HHMI) international research scholar Stephen W. Scherer, and colleagues, is expected to change the way researchers think about genetic diseases and human evolution.
Genes usually occur in two copies, one inherited from each parent. Scherer and colleagues found approximately 2,900 genes--more than 10 percent of the genes in the human genome--with variations in the number of copies of specific DNA segments. These differences in copy number can influence gene activity and ultimately an organism's function.
To get a better picture of exactly how important this type of variation is for human evolution and disease, Scherer's team compared DNA from 270 people with Asian, African, or European ancestry that had been compiled in the HapMap collection and previously used to map the single nucleotide changes in the human genome. Scherer's team mapped the number of duplicated or deleted genes, which they call copy number variations (CNVs). They reported their findings in the November 23, 2006, issue of the journal Nature.
Scherer, a geneticist at the Hospital for Sick Children and the University of Toronto, and colleagues searched for CNVs using microarray-based genome scanning techniques capable of finding changes at least 1,000 bases (nucleotides) long. A base, or nucleotide, is the fundamental building block of DNA. They found an average of 70 CNVs averaging 250,000 nucleotides in size in each DNA sample. In all, the group identified 1,447 different CNVs that collectively covered about 12 percent of the human genome and six to 19 percent of any given chromosome--far more widespread than previously thought.
Not only were the changes common, they also were large. "We'd find missing pieces of DNA, some a million or so nucleotides long," Scherer said. "We used to think that if you had big changes like this, then they must be involved in disease. But we are showing that we can all have these changes."
The group found nearly 16 percent of known disease-related genes in the CNVs, including genes involved in rare genetic disorders such as DiGeorge, Angelman, Williams-Beuren, and Prader-Willi syndromes, as well as those linked with schizophrenia, cataracts, spinal muscular atrophy, and atherosclerosis.
In related research published November 23, 2006, in an advance online publication in Nature Genetics, Scherer and colleagues also compared the two human genome maps--one assembled by Celera Genomics, Inc., and one from the public Human Genome Project. They found thousands of differences.
"Other people have [compared the two human genome sequences]," Scherer said, "but they found so many differences that they mostly attributed the results to error. They couldn't believe the alterations they found might be variants between the sources of DNA being analyzed."
A lot of the differences are indeed real, and they raise a red flag, he said.
Personalized genome sequencing--for individualized diagnosis, treatment, and prevention of disease--is not far off, Scherer pointed out. "The idea [behind comparing the human genome sequences] was to come up with a good understanding of what we're going to get when we do [personalized sequencing]," he explained. "This paper helps us think about how complex it will be."
So my question is....
If human beings are less genetically similar to each other than previously thought, does this imply that scientists might have been wrong in thinking humans and chimps are 98% similar?
PS- Yes, I realize the article I posted is far from the final word on the matter. I also realize that the point I am making is far from what would be required to falsify evolution or common ancestry. Nonetheless, I thought it would be an interesting subject for discussion here.
