The Darwinian Interlude
- From: "whitesickle@xxxxxxx" <whitesickle@xxxxxxx>
- Date: Mon, 6 Feb 2006 13:59:28 -0500 (EST)
[1]
March 2005
The Darwinian Interlude
Biotechnology will do away with species. Good: cultural evolution is
better than natural selection.
By Freeman Dyson
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 world's 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.
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
life.
.
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