[Paleopsych] Freeman Dyson: The Darwinian Interlude

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The Darwinian Interlude

    Freeman Dyson is professor emeritus of physics at the Institute for
    Advanced Study in Princeton, NJ. His research has focused on the
    internal physics of stars, subatomic-particle beams, and the origin of

    Carl Woese published a provocative and illuminating article, A New
    Biology for a New Century, in the June 2004 issue of Microbiology and
    Molecular Biology Reviews. His main theme is the obsolescence of
    reductionist biology as it has been practiced for the last hundred
    years, and the need for a new biology based on communities and
    ecosystems rather than on genes and molecules. He also raises another
    profoundly important question: when did Darwinian evolution begin? By
    Darwinian evolution he means evolution as Darwin himself understood
    it, based on the intense competition for survival among
    noninterbreeding species. He presents evidence that Darwinian
    evolution did not go back to the beginning of life. In early times,
    the process that he calls horizontal gene transfer, the sharing of
    genes between unrelated species, was prevalent. It becomes more
    prevalent the further back you go in time. Carl Woese is the worlds
    greatest expert in the field of microbial taxonomy. Whatever he
    writes, even in a speculative vein, is to be taken seriously.

    Woese is postulating a golden age of pre-Darwinian life, during which
    horizontal gene transfer was universal and separate species did not
    exist. Life was then a community of cells of various kinds, sharing
    their genetic information so that clever chemical tricks and catalytic
    processes invented by one creature could be inherited by all of them.
    Evolution was a communal affair, the whole community advancing in
    metabolic and reproductive efficiency as the genes of the most
    efficient cells were shared. But then, one evil day, a cell resembling
    a primitive bacterium happened to find itself one jump ahead of its
    neighbors in efficiency. That cell separated itself from the community
    and refused to share. Its offspring became the first species. With its
    superior efficiency, it continued to prosper and to evolve separately.
    Some millions of years later, another cell separated itself from the
    community and became another species. And so it went on, until all
    life was divided into species.

    The basic biochemical machinery of life evolved rapidly during the few
    hundred million years that preceded the Darwinian era and changed very
    little in the following two billion years of microbial evolution.
    Darwinian evolution is slow because individual species, once
    established, evolve very little. Darwinian evolution requires  species
    to become extinct so that new species can replace them. Three
    innovations helped to speed up the pace of evolution in the later
    stages of the Darwinian era. The first was sex, which is a form of
    horizontal gene transfer within species. The second innovation was
    multicellular organization, which opened up a whole new world of form
    and function. The third was brains, which opened a new world of
    coördinated sensation and action, culminating in the evolution of eyes
    and hands. All through the Darwinian era, occasional mass extinctions
    helped to open opportunities for new evolutionary ventures.

    Now, after some three billion years, the Darwinian era is over. The
    epoch of species competition came to an end about 10 thousand years
    ago when a single species, Homo sapiens, began to dominate and
    reorganize the biosphere. Since that time, cultural evolution has
    replaced biological evolution as the driving force of change. Cultural
    evolution is not Darwinian. Cultures spread by horizontal transfer of
    ideas more than by genetic inheritance. Cultural evolution is running
    a thousand times faster than Darwinian evolution, taking us into a new
    era of cultural interdependence that we call globalization. And now,
    in the last 30 years, Homo sapiens has revived the ancient
    pre-Darwinian practice of horizontal gene transfer, moving genes
    easily from microbes to plants and animals, blurring the boundaries
    between species. We are moving rapidly into the post-Darwinian era,
    when species will no longer exist, and the evolution of life will
    again be communal.

    In the post-Darwinian era, biotechnology will be domesticated. There
    will be do-it-yourself kits for gardeners, who will use gene transfer
    to breed new varieties of roses and orchids. Also, biotech games for
    children, played with real eggs and seeds rather than with images on a
    screen. Genetic engineering, once it gets into the hands of the
    general public, will give us an explosion of biodiversity. Designing
    genomes will be a new art form, as creative as painting or sculpture.
    Few of the new creations will be masterpieces, but all will bring joy
    to their creators and diversity to our fauna and flora.

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