"It is totally wrong. It's wrong like infectious medicine was wrong
before Pasteur. It's wrong like phrenology is wrong. Every major tenet
of it is wrong," said the outspoken biologist Lynn Margulis about her
latest target: the dogma of Darwinian evolution.
Margulis has been right about what is wrong before. She shook up the
world of microbiology in 1965 with her outrageous thesis of the
symbiotic origin of nucleated cells. To the disbelief of
traditionalists, she claimed that free-roaming bacteria cooperated to
form cells. Then in 1974, Margulis again rattled the cage of biology by
suggesting (jointly with James Lovelock) that atmospheric, geological,
and biological processes on Earth are so interconnected that they act as
a single living, self-regulating system -- Gaia. Margulis was now
denouncing the modern framework of the century-old theory of Darwinism,
which holds that new species build up from an unbroken line of gradual,
independent, random variations.
Margulis is not alone in challenging the stronghold of Darwinian theory,
but few have been so blunt. Disagreeing with Darwin resembles
creationism to the uninformed; therefore the stigma that any taint of
creationism can bring to a scientific reputation, coupled with the
intimidating genius of Darwin, have kept all but the boldest iconoclasts
from doubting Darwinian theory in public.
What excites Margulis is the remarkable incompleteness of general
Darwinian theory. Darwinism is wrong by what it omits and by what it
A number of microbiologists, geneticists, theoretical biologists,
mathematicians, and computer scientists are saying there is more to life
than Darwinism. They do not reject Darwin's contribution; they simply
want to move beyond it. I call them the "postdarwinians." Neither Lynn
Margulis nor any other postdarwinian denies the true ubiquity of natural
selection in evolution. Their disagreement is with the very sweeping
nature of the Darwinian argument, the fact that in the end it doesn't
explain much, and the emerging evidence that Darwinism alone may not be
sufficient to explain all we see. The vital questions the postdarwinians
raise are: What are the limits to natural selection? What can't
evolution make? And if blind natural selection has limits, what else is
operating within or beyond evolution as we understand it?
According to the ordinary contemporary Darwinian biologist, there is
nothing we see in nature that cannot be explained by the elemental
process of natural selection. In academic jargon this stance is called
selectionism, and the position is nearly universal among biologists
working today. Because this stance is more extreme that what Darwin
himself believed, it is sometimes called neodarwinism.
In the pursuit of artificial evolution, the limits (if any) to natural
selection, or to evolution in general, take on practical importance.
We'd like an artificial evolution that generates neverending diversity,
but so far, that isn't so easy to do. We'd like to extend the dynamics
of natural selection to very large systems with many levels of scale,
but we don't know how far natural selection can be extended. We'd like
an artificial evolution that we could control a bit more than we control
organic evolution. Is that possible?
Questions like these have prompted the postdarwinians to reconsider
alternative theories of evolution -- many that existed before Darwin -- that
were eclipsed by the dominance of Darwinism. In a kind of intellectual
survival of the fittest, contemporary biology places very little
importance on these "inferior" beaten theories, so they survive only in
marginal out-of-print books. But the ideas of these creative theories
are suited to a new niche called artificial evolution and are cautiously
being resurrected for examination.
The most stellar naturalists, geologists, and biologists of Darwin's
time hesitated (despite Darwin's constant badgering) to accept his
general theory in full when it was published in 1859. They accepted his
transmutation theory -- "descent with modification," or the gradual
transmutation of new species from preexisting species. But they remained
skeptical of his selectionist reasoning -- that tiny random improvements
were all there was to it -- because they felt Darwin's explanation did not
accurately fit the facts of nature, facts with which they were
intimately familiar in a way that is rare today in this era of
specialization and indoor laboratories. But since they could offer
neither compelling disproof nor an alternative theory of equal quality,
their forceful criticisms were buried in correspondence and scholarly
Darwin didn't offer a concrete mechanism by which his proposed natural
selection would take place, either. He was ignorant about genes, for
starters. The first fifty years following the publication of Darwin's
tour de force were ripe with supplemental theories of evolution, until
Darwin's dominance was clinched by the discovery of genes and later DNA.
Almost every radical evolutionary conviction circulating today has as
its source some thinker in the years after Darwin but before acceptance
of his theory as dogma.
No one was more sensitive to the weaknesses of Darwinian theory than
Darwin himself. As an example of trouble, Darwin volunteered the
astounding multifaceted sophistication of the human eye. (Every critic
of Darwin since has also used his example.) The exquisite design of
interacting lens, iris, retina, etc., seems to defy the plausibility of
Darwin's "slight, incremental" chance improvements. As Darwin wrote to
his American friend Asa Gray, "About the weak points I agree. The eye to
this day gives me a cold shudder." The difficulty Gray had was imagining
how any portion of an unfinished eye, a retina without lens or vice
versa, would be useful to its possessor. Since nature cannot hoard
innovations ("Hey, this will come in handy in the Cretaceous!"), every
stage in development must be immediately useful and viable.
Breakthroughs have to work the first time. Even clever humans can't
design in such a consistently demanding manner. Therefore nature appears
superhuman in its ability to create.
Imagine, says Darwin, that we extrapolate the tiny microevolutionary
changes we see in domesticated breeding -- a pea with extra -- large pods made
larger, or a short horse bred shorter. Imagine if we extend those slight
changes caused by selection over millions of years; we add up all the
minute differences until we see major change. This is what makes coral
reefs and armadillos out of bacteria, Darwin said -- accumulated
microchange. Darwin asks that we extend the logic of microchange to
cover the grand scale of Earth and Time.
The argument that natural selection can be extended to explain
everything in life is a logical argument. But human imagination and
human experience know that what is logical is not always what is so. To
be logical is a necessary but insufficient reason to be true. Every
swirl on a butterfly wing, every curve of leaf, every species of fish is
explained by adaptive selection in neodarwinism. There seems to be
absolutely nothing that cannot be explained in some way as an adaptive
advantage. But, as Richard Lewontin, a renowned neodarwinist, says,
"Natural selection explains nothing, because it explains
Biologists cannot (or at least they have not) ruled out the role of
other forces at work in nature producing similar effects in evolution.
Therefore, until evolution is duplicated under controlled conditions, in
the wild, or in a lab, neodarwinism remains a nice "just-so" story -- more
like history than science. Philosopher of science Karl Popper said
bluntly that neodarwinism is not a scientific theory at all, since it
cannot be falsified. "Neither Darwin, nor any Darwinian, has so far
given an actual causal explanation of the adaptive evolution of any
single organism or any single organ. All that has been shown -- and this is
very much [sic] -- is that such an explanation might exist -- that is to say,
[these theories] are not logically impossible."
Life has a causality problem. Any coevolved organism seems to be
self-created, making causality onerous to pin down. Part of the search
for more complete explanations of evolution is a search for a more
complete logical understanding of spontaneous complexity and the rules
by which entities may emerge from a web of parts. The quest for
artificial evolution -- so far done primarily in computer simulations -- is
very much tied into a new way of establishing proof in science. Previous
to the advent of ubiquitous computers, science consisted of two facets:
theory and experiment. A theory would shape an experiment, and then the
experiment would confirm or disprove the theory.
But computers have birthed a third way of doing science: by simulation.
A simulation is at once both a theory and an experiment. By running a
computer model, such as Tom Ray's artificial evolution, we are trying
out a theory and also running something real and accumulating
falsifiable data. It may be that the dilemma of ascertaining causality
in complex systems will be bypassed by these new methods of
understanding, wherein one studies the real by modeling working
Artificial evolution is at once a theory and test for natural evolution,
and something original in itself.