From: Josh Bembenek (jbembe@hotmail.com)
Date: Wed Apr 30 2003 - 14:30:11 EDT
Another FYI about the *degree* of disimilarity. Forgive the odd formatting,
I copied it from Nature.
Josh
Human Genome Organisation Meeting,
Cancun, Mexico, April 2003
Chimps expose humanness
Preliminary genome comparison points to primate individuality.
29 April 2003
HELEN PEARSON
may be only 94% the same as
By studying chimpanzees, scientists are honing their genetic view of
humanity, researchers told this week's meeting of the Human Genome
Organisation in Cancun, Mexico.
A group presented the first detailed comparison between a large chunk of
human DNA and the equivalent from our closest relative. The
genetic make-up of chimpanzee chromosome 22 is hot off the press, having
just been sequenced, and matches human chromosome 21.
The data call for some revision of the estimated genetic similarity
between us and our closest relatives. Previously, human and chimp
genetic sequences were quoted as being nearly 99%
identical, with a difference of only a few DNA's letters. In fact, the
similarity may be as low as 94-95%, says Todd Taylor of the RIKEN Genomic
Sciences Center in Yokohama, Japan.
Taylor's team factors in whole segments that they found to have been
added to or subtracted from one of the genomes; previous estimates
were often produced by comparing smaller areas. "There's still not a good
way to say how much we're similar," admits Taylor.
It is not yet clear how these rearrangements and single-letter changes
underlie 'human' characteristics such as talking, abstract
thinking and certain diseases. But, "if we want to find the
very fine differences that make us human we have to look at our closest
relative", Taylor says.
The team found that one gene that is linked to Alzheimer's disease - a
brain disorder that does not seem to afflict chimps - produces a
slightly different protein in chimps from the corresponding
human version. In all, around 16% of genes in the compared
sequences have such variations.
The completed human genetic sequence is not enough to tell us everything
about ourselves
Yoshiyuki Sakaki
HUGO
Another good example, says geneticist Stephen Scherer of the Hospital
for Sick Children in Toronto, was found last year in a gene
called FOXP2 , which seems to control human language. Chimpanzees have two
key changes in the gene, which may prevent them from articulating
speech.
Taylor's is one of two international groups that are now working their
way through the chimpanzee's genome. They also hope to pinpoint
cases in which, although chimp and human genes are very similar, they are
active at different times or places in the body.
Researchers announced only last week that they have largely completed
the human genetic sequence. But "it's not enough to tell us
everything about ourselves", says Human Genome Organisation
president Yoshiyuki Sakaki, also at the RIKEN genome centre.
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