From: Hal Finney (hal@finney.org)
Date: Thu Dec 05 2002 - 12:20:29 MST
Robert Bradbury writes:
> The NY Times has an interesting article about a comparison
> between the mouse and human genomes.
>
> Similarities Found in Mouse Genes and Human's
> http://www.nytimes.com/2002/12/05/science/05MOUS.html?pagewanted=print
> ...
> A personal observation suggests that with this amount of similarity
> in the genomes with a 20-fold difference in longevity suggests that
> the rate of aging is under the control of a limited number of genes
> (probably hundreds or less).
That may be true, but surely there are a great many other differences
between humans and mice! The most obvious is size; we weigh hundreds of
times more than mice. Then there is body shape, diet, behavioral habits,
gestation period, number of babies, not to mention intelligence.
It's hard to understand how such a relatively small number of genes being
different can lead to such enormous differences between the two species.
Longevity seems like only a small part of the picture.
One thing I'm finding confusing in the articles is just how different
the genomes are. We used to hear that humans and chimpanzees were
something like 98% the same. This article from last May,
http://www.newscientist.com/news/news.jsp?id=ns99992352, says:
"Mice and men share about 97.5 per cent of their working DNA, just one
per cent less than chimps and humans. The new estimate is based on the
comparison of mouse chromosome 16 with human DNA. Previous estimates
had suggested mouse-human differences as high as 15 per cent."
But this article from yesterday,
http://www.newscientist.com/news/news.jsp?id=ns99993147, says that 99%
of mouse and human DNA is the same. The Times on the other hand avoids
such comparisons and just talks about numbers of genes.
Another curious discrepency comes from this article also from May,
http://www.newscientist.com/news/news.jsp?id=ns99992253, which says,
"We'll have the rat [DNA sequence] by the end of the year." While the
current press release, http://www.genome.gov/page.cfm?pageID=10005831,
says that the next mammals in line for sequencing are the chimpanzee,
chicken, cow, and dog. Where'd the rat go? Surely if they could say
in May that they'd have the rat by the end of the year, they must have
been pretty far along at that time.
It's also worth noting that despite the spate of publicity, the mouse
genome was actually published last May! The flurry of press reports are
because only now did the event get into the scientific journals due to
publishing delays. But if you look at some of the articles above from
last May you will see much the same commentary that is being recycled now.
It's strange how science goes, it's like nothing counts until it appears
in the paper journals. It's a sort of mass delusion or psychosis where
people pretend that reality doesn't exist until it gets blessed by some
editor. It'll be good to see those dinosaurs disappear in a few years,
because it will force people to face reality a little more squarely,
unprotected by pretense and convention.
Hal
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