Re: Fwd: Genome's Riddle: Few Genes, Much Complexity

From: Ray Recchia (
Date: Wed Feb 14 2001 - 00:04:38 GMT

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    Date: Tue, 13 Feb 2001 19:04:38 -0500
    From: Ray Recchia <>
    Subject: Re: Fwd: Genome's Riddle: Few Genes, Much Complexity
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    I mentioned these recombinations in an earlier post but with Wade's post I
    thought I might mention that similar processes can be seen at work in
    memetics. The analogies are loose and I certainly wouldn't want to make
    too much of them but I'll list a couple of examples. My understanding is
    that in the mid 1900's a bunch of physicists became interested in biology
    and using the intellectual tools they developed as physicists they became
    important movers in the search for the molecular basis of inheritance. It
    is also my understanding that a similar invasion of biology by geologists a
    century earlier provided a great deal of support for evolutionary
    theory. The analogy applied is that knowledge and techniques in developed
    in one field of science were transferred to another without rebuild from

    There are also analogies to speciation that can be found in human
    history. One way that species form is through separation and isolation of
    groups of a starting species. Left on their own, the species evolve in
    different ways. By analogy I would point to the history of chemistry. In
    the 1700's the French and Germans developed different theories that
    appeared to contradict each other. The French developed an atomic theory,
    which the German's worked the basics of electrochemistry. Looking back,
    neither theory was completely right, nor was either theory completely
    wrong. However, each on its own was able to make significant
    advancements. The French theory was more sophisticated, and answered more
    questions than the German theory and could be seen as the more fit of the
    two. Later both theories merged to form the basis for modern chemical
    theory. Both of the earlier theories were important, and it is not clear
    that left to its own French theory would have been able to overcome its
    flaws at anywhere near the same speed as if those same German scientists
    had been devoting their energy to French theory instead.

    Ray Recchia

    At 08:42 AM 2/13/2001 -0500, you wrote:
    >There is, in today's NYTimes, yet another article about the genome- but
    >I've only included what seemed to me especially interesting below- which
    >is a mechanism involved in replication that, I think, might well describe
    >mechanisms we have started to call memetic.
    >- Wade
    >Genome's Riddle: Few Genes, Much Complexity
    >Turning from genes to chromosomes, one of the most interesting
    >discoveries in this week's papers concerns segmental duplications, or the
    >copying of whole blocks of genes from one chromosome to the other. These
    >block transfers are so extensive that they seem to have been a major
    >evolutionary factor in the genome's present size and architecture. They
    >may arise because of a protective mechanism in which the cell reinserts
    >broken-off fragments of DNA back into the chromosomes.
    >In Celera's genome article, Dr. Venter presents a table showing how often
    >blocks of similar genes in the same order can be found throughout the
    >genome. Chromosome 19 seems the biggest borrower, or maybe lender, with
    >blocks of genes shared with 16 other chromosomes.
    >Much the same set of large-scale block transfers seems to have occurred
    >in the mouse genome, Dr. Venter writes, suggesting that the duplications
    >"appear to predate the two species' divergence" about 100 million years
    >ago. He hopes that by sequencing the genomes of many other species he can
    >reconstruct the history of the genome's formation.
    >Segmental duplication is an important source of innovation because the
    >copied block of genes is free to develop new functions. An idea enshrined
    >in many textbooks is that the whole genome of early animals has twice
    >been duplicated to form the vertebrate lineage. There are several cases
    >in which one gene is found in the roundworm or fly and four very similar
    >genes in vertebrates. (The quadruplicated genes that failed to find a
    >useful role would have been shed from the genome.)
    >But neither Celera nor the consortium has found any evidence for the
    >alleged quadruplication. If this venerable theory is incorrect, the
    >four-gene families may all arise from segmental duplication.
    >This was distributed via the memetics list associated with the
    >Journal of Memetics - Evolutionary Models of Information Transmission
    >For information about the journal and the list (e.g. unsubscribing)

    This was distributed via the memetics list associated with the
    Journal of Memetics - Evolutionary Models of Information Transmission
    For information about the journal and the list (e.g. unsubscribing)

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