Around the world, a few naturalists are conducting long-term
observations of evolving populations of organisms in the wild: snails in
Tahiti, fruitflies in Hawaii, finches in the Galapagos, and lake fish in
Africa. Every year that these studies go on, there is a better chance
that scientists can unequivocally demonstrate long-term evolution in
action in the field. Shorter-term studies using bacteria, and recently
flour beetles, show short-term evolution of organisms in the lab. So
far, these experiments with populations of living creatures have matched
the results expected from neodarwinian theory. The beaks of finches in
the Galapagos really do thicken over time in response to drought-induced
changes in their food supply, just as Darwin predicted.
These careful measurements prove that self-governing adaptation does
spontaneously occur in nature. They also unequivocally demonstrate that
noticeable change can emerge on its own by summing up the steady
unnoticeable work of incremental deletions of the unfit. But the results
do not show new levels of diversity, new kinds of creatures, or even new
Despite a close watch, we have witnessed no new species emerge in the
wild in recorded history. Also, most remarkably, we have seen no new
animal species emerge in domestic breeding. That includes no new species
of fruitflies in hundreds of millions of generations in fruitfly
studies, where both soft and harsh pressures have been deliberately
applied to the fly populations to induce speciation. And in computer
life, where the term "species" does not yet have meaning, we see no
cascading emergence of entirely new kinds of variety beyond an initial
burst. In the wild, in breeding, and in artificial life, we see the
emergence of variation. But by the absence of greater change, we also
clearly see that the limits of variation appear to be narrowly bounded,
and often bounded within species.
The standard explanation is that we are measuring a geological event in
real time on a ridiculously infinitesimally small time span, so what do
we expect? Life was bacterialike for billions of years before much
happened. Patience, please! This is why Darwin and other biologists
turned to the fossil record for proof of evolution. And although the
fossil record indisputably exhibits Darwin's larger thesis -- that over
time modification of form is accumulated in descendants -- the fossil
record has not proved that this change is due solely or even primarily
to natural selection.
No one has yet witnessed, in the fossil record, in real life, or in
computer life, the exact transitional moments when natural selection
pumps its complexity up to the next level. There is a suspicious
barrier in the vicinity of species that either holds back this critical
change or removes it from our sight.
Steven Jay Gould believes the exact transformation periods are removed
from the sight of the fossil record by their incredibly instantaneous
(evolutionarily speaking) mode. Whether his theory is correct or not,
the evidence points to a natural limiting factor for extrapolated
microchange that must somehow be overcome by evolution.
Synthetically reproduced protolife and artificial evolution in computers
have already unearthed a growing body of nontrivial surprises. Yet
artificial life suffers from the same malaise that afflicts its cousin,
artificial intelligence. No artificial intelligence that I am aware
of -- be it autonomous robot, learning machine, or massive cognition
program -- has run more than 24 hours in succession. After a day,
artificial intelligence stalls. Likewise, artificial life. Most runs of
computational life fizzle out of novelty quickly. While the programs
sometimes keep running, churning out minor variation, they ascend to no
new levels of complexity or surprise after the first spurt (and that
includes Tom Ray's world of Tierra). Perhaps given more time to run,
they would. Yet, for whatever reason, computational life based on
unadorned natural selection has not seen the miracle of open-ended
evolution that its creators, and I, would love to see.
As the French evolutionist Pierre Grasse said, "Variation is one thing,
evolution quite another; this cannot be emphasized strongly enough....
Mutations provide change, but not progress." So while natural selection
may be responsible for microchange -- a trend in variations -- no one can say
indisputably that it is responsible for macrochange -- the open-ended
creation of an unexpected novel form and progress toward increasing
Many of the promises for artificial evolution foretold in this book will
still come about if artificial evolution is merely adaptive microchange.
Spontaneously directed variation and selection is an incredibly powerful
problem solver. Natural selection indeed works over the immediate short
term. We can use it to find what we can't see and fill in what we can't
imagine. The question comes down to whether random variation and
selection are sufficient alone to produce ever increasing novelty over
the very long term. And if "natural selection is not enough" then what
else might be at work in wild evolution, and what may we import into
artificial evolution that will generate self-organizing complexity?
Most critics of natural selection concede that Darwin got "survival of
the fittest" right. Natural selection primarily means the destruction of
the unfit. Once fitness is created, natural selection is peerless for
winnowing out the duds.
But creating something useful is the bugaboo. What the Darwinian
perspective neglects is a plausible explanation for the origin of
fitness. Where does fitness come from before it is selected? In the
popular rendition of neodarwinism today, the origin of fitness is
credited to random variation. Random variation within chromosomes
produces a random variation in the developmental growth of the organism,
which every now and then bestows increased fitness on the whole
organism. Fitness is generated randomly.
As experiments in wild and artificial evolution have shown, this simple
process can steer coordinated change over the short time. But given that
natural selection weeds out all the uncountable failures, and that there
is uncountable time, can random mutation generate the unbroken series of
needed winners for selection to choose from? Darwinian theory has the
sizable burden of proving that the negative, braking power of selective
demise, coupled with the blind chaotic power of randomness, can produce
the persistent, creative, positive drive toward more complexity we see
sustained in nature over billions of years.
Postdarwinism suggests that other forces are at work in evolution in the
long run. These lawful mechanisms of change reorganize life into new
fitnesses. These unseen dynamics extend the Library in which natural
selection may operate. This deepened evolution need not be any more
mystical than natural selection is. Think of each dynamic-symbiosis,
directed mutation, saltationism, self-organization -- as a mechanism that
will foster evolutionary innovation over the long term in complement to
Darwin's ruthless selection.