Caveats aside, I discern about seven large trends or directions
emerging from the ceaseless, hourly toil of organic evolution. These
trends, as far as anyone can tell, are also the seven trends that will
bias artificial evolution when it goes marathon; they may be said to be
the Trends of Hyperevolution: Irreversibility, Increasing Complexity,
Increasing Diversity, Increasing Numbers of Individuals, Increasing
Specialization, Increasing Codependency, Increasing
Irreversibility. Evolution doesn't back up. (Also
known as Dollo's Law.) There are exceptions to the no-backup principle.
A whale in one sense backed up to be a fish again. But it is the
exception that proves the rule. In general, current manifestations of
life do not work on invading past niches.
Nor are hard-won attributes easily given up. It is an axiom in cultural
evolution that technologies once invented are never uninvented. Once a
vivisystem discovers language or memory it does not retreat from it.
The presence of life also does not retreat. I am aware of no geological
domain that organic life has infiltrated and then retreated from. Once
life settles in an environment (hot springs, alpine rock, robots) it
will tenaciously maintain some presence there. Life exploits the
inorganic world, recklessly transforming it into the organic. "Atoms,
once drawn into the torrent of living matter, do not readily leave it,"
Prelife Earth was, by definition, a sterile planet. It is commonly
accepted that although sterile, the Earth was simmering with the
ingredients life needed. In essence it was a global agar plate waiting
to be inoculated. Think of a immense 8,000-mile-wide bowl of pasteurized
chicken broth. One day you drop a cell into it, and the next day, by the
power of exponential growth, the oceanic bowl is thick with cells. In a
few decades, all varieties of cells have wormed their way into every
nook. Even if it took a hundred years, that is but a nano-blink in
geological time. Life is born. Blink. Life is irrepressible.
Having infiltrated computers, artificial life will henceforth never
retreat from being in some computer, somewhere.
Increasing Complexity. When I ask friends if evolution
has a direction the common answer I get (if I get any at all) is
"towards more complexity."
While it seems obvious to almost everyone that evolution moves toward
greater complexity, we have few definitions of complexity that really
mean anything. Modern biologists question the notion that life heads
toward complexity. Steven Jay Gould has told me flatly, "The illusion of
a move toward increasing complexity is an artifact. You need to build
simple things first, so naturally complex things come later."
But there are plenty of simple things nature has never made. If there
was not a drive toward complexity, why not stop at bacteria and invent
millions of more one-celled varieties. Or why not stop at fish and fill
in all possible fish forms? Why make things more complicated? For that
matter, why did life start out simple? There is no law we know of that
says things have to get more complex.
If there is a true trend toward complexity, there must be something
pushing it. In the last hundred years a number of theories have been
proposed as to what drives apparent complexity. They could be listed by
the following overlapping summaries (and the year they were first
Runaway replication and duplication of parts makes complexity
The ruggedness of real environments causes differentiation of parts,
which aggregate into complexity (1890).
Complexity is more thermodynamically efficient (1960).
Complexity is an inadvertent by-product of selection for other
A complex organism creates a niche for more complexity around it;
thus complexity is a positive feedback loop amplifying itself (1969).
Since it is easier for a system to add a part than to remove a part,
complexity accumulates (1976).
Nonequilibrial systems accumulate complexity when they dissipate
entropy, or wasted heat (1972).
Chance alone produces complexity (1986).
Endless arms races escalate complexity (1986).
Because the term complexity is vague and unscientific at present, no one
has done a systematic study of the fossil record to determine whether or
not quantitative complexity increases over time. A few studies of
particular short lineages of organisms have been done (using differing
measures of complexity) and they have shown that sometimes some aspects
of these creatures increase in complexity and sometimes they don't. In
brief, we don't know for sure what happens as organisms apparently
Increasing Diversity. This one needs some careful
clarification. One famous bed of fossils, the soft-bodied animals in the
Burgess Shale, is currently forcing a rethinking of what we mean by
diversity. As Gould tells in Wonderful Life, the Burgess Shale show a
remarkable range of alien organisms thriving during the innovation boom
of the Cambrian. These fantastic creatures are far more diverse in their
basic plan than the creatures we descended from. What we see since the
Burgess Shale, Gould argues, is decreasing diversity of basic plans,
with vastly increasing quantities of minor gingerbreading.
For instance, life churns out millions more kinds of insects, in ever
more glorious modifications, but no more new kinds of things such as
insects. Endless variations of trilobites, but no new classes such as
trilobites. And since the Burgess Shale displays a smorgasbord of
structural variety that beats the paltry choice of basic plans which
life now offers in the same area, one could argue that the conventional
view of diversity beginning small and ballooning over time is inverted.
If you count diversity as significant variety, then diversity is
shrinking. Some paleontologists are calling this more fundamental
diversity of ground plan "disparity" to distinguish it from the ordinary
diversity of species. There is more significant difference (fundamental
disparity) between a hammer and a saw, than there is between an electric
table saw and a power circular saw or all the thousands of baroque
electrical appliances manufactured today. Gould puts it this way, "Three
blind mice of differing species do not make a diverse fauna, but an
elephant, a tree, and an ant do -- even though each assemblage contains
just three species." We give more weight to fundamentals of clearly
different logic in recognition that it's hard to come up with really
innovative basic plans (try to imagine a universal alternative to the
Because versatile basic plans are rare, when the majority of them go
belly up, as they did after the Cambrian, never to be replaced, it's big
news. This leads Gould to the "surprising fact of life's history -- marked
decrease in disparity followed by an outstanding increase in diversity
within the few surviving designs." Take ten designs, throw away nine,
and do the tenth one up in a bazillion variations, like beetles. The
"cone of increasing diversity" we associate with evolution since the
Cambrian, then, is more appropriately figured within the level of
species diversity, because more species types are alive today than ever
Increasing Numbers of Individuals. There are also more
individual organisms in total living now than a billion years ago, or
perhaps even a million years ago. Presumably life originated only once,
so there was once only the first living organism of Adamlike oneness.
Now there are uncounted legions.
There is another important way the sheer number of living entities
increases. In a hierarchical manner, supergroups and subgroups create
individuals. Bees band together to form a colony, so now the number of
individuals total the number of bees plus one superorganism. A person is
an individual made up of millions of individual cells which may also be
counted and added to the increasing total of individual lives. Each of
these cells may have a parasite, thus more individuals. In many
overlapping ways, notions of individuals can be nested within each other
in the same limited space. So within one cubic volume, a hive of bees
with cells and mites and viral infections may have more individuals than
the same volume full of bacteria. As Stanley Salthe writes in Evolving
Hierarchical Systems, "An indefinite number of unique individuals can
exist in a finite material world if they are nested within each other
and that world is expanding."
Increasing Specialization. Life starts as a process
accomplishing many things in general. Over time a single life is
differentiated into many individuals doing more specialized things. Just
as a general egg cell differentiates through epigenesis to become a
legion of specialized cells, so in evolution animals and plants split up
into varieties more dependent on narrower niches. The word "evolution,"
in fact, originally meant the unrolling development of an egg cell into
an embryonic creature. The term was only later applied to organic change
over time for the first time by Herbert Spencer, who defined evolution
(in 1862) as "a change from an indefinite, incoherent homogeneity, to a
definite, coherent heterogeneity; through continuous differentiations
The trends listed above can be gathered together with increasing
specialization to create the following broad picture: Life begins as
one, simple, vague, unformed creativity which, over time becomes more
and more fixed into a cloud of precise, inflexible, machinelike
structures. Once differentiated, cell lines rarely revert to the more
general. Once specialized, animal lines rarely revert to the more
general. Over time the percentage of specialized organisms increase, the
kinds of specialization increase, and the degree of specialization
increases. Evolution moves toward more detail.
Increasing Codependency. Biologists have noticed that
primitive organisms have a direct dependency on the physical
environment. Some bacteria live inside rock; some lichens eat stone.
Slight perturbations of these organisms' physical habitat have a strong
impact (lichens are miners' canaries for acid-rain pollution for this
reason). As life evolves it unbinds from the inorganic and interacts
more with the organic. While plants are rooted directly to the earth,
animals, which are rooted to the plants, are freer from the earth.
Amphibians and reptiles generally fertilize their eggs and abandon them
to the elements, while birds and mammals raise their young, and so are
bound closer to life from birth. Over time the close intimacy with earth
and minerals is replaced by a dependence on other living things.
Parasites cuddling in the warm interior of an animal's gut may never
touch anything outside of organic life. Likewise social animals: while
ants may live in the ground, their individual lives are far more
dependent upon the other ants than upon the soil around them. Deepening
sociality is yet another form of life's increasing codependence on other
life. Humans are an extreme example of increasing dependence on life
rather than the abiotic.
Evolution pulls life away from the inert and binds to itself whenever
possible, manufacturing a great something out of nothing.
Increasing evolvability. In 1987, Cambridge zoologist
Richard Dawkins presented a paper at the First Artificial Life Workshop
entitled "The Evolution of Evolvability," wherein he explored the
feasibility and advantages of evolution evolving itself. Around the same
time Christopher Wills writing in Wisdom of the Genes, also published a
scenario of how genes might control their own evolvability.
Dawkins's thinking was inspired by his attempts to create an artificial
evolution in Biomorph Land. He realized while playing God that certain
rare innovations would not only provide an immediate advantage to an
individual but were "evolutionarily pregnant" and loosened up future
offspring's ability to vary widely. He used the example of the first
segmented animal in real life which he called "a freak ... [which was]
not a dramatically successful individual." But something about animal
segmentation was a watershed event that birthed a line of descendants
who were champion evolvers.
Dawkins proposed a higher-level natural selection "which favors, not
just adaptively successful phenotypes, but a tendency to evolve in
certain directions, or even just a tendency to evolve at all." In other
words, evolution would select not only for survivability, but also for
The ability to evolve does not rest in a single trait or function -- such
as mutation rate -- yet a function such as mutation rate will play a role
in an organism's evolvability. If a species cannot generate requisite
variety, it won't evolve. Its ability to modify its body plays a role in
its evolvability, as does its behavioral plasticity. The flexibility of
its genome is of critical importance. Ultimately the evolvability of a
species is a systems characteristic that does not dwell in any single
place, just as an organism's ability to survive does not rest in any
Like all traits selected by evolution, evolvability must be
accumulative. A weak innovation once adopted can serve as the platform
for the birth of a stronger innovation. In this way, weak evolvability
establishes an ongoing base for further evolvability to arise. Over the
very long term, evolvability is an essential component of survivability.
Thus a line of organisms with genes wired to increase evolvability would
accumulate a decided ability (and advantage) to evolve. And so on ad
The evolution of evolution is like getting the wish that Aladdin's lamp
won't let you have: the wish for three more wishes. It's the power to
change the rules of the game legally. Marvin Minsky noticed a similar
power of change-which-changes-its-own-rules in the development of a
child's mind. Minsky: "A mind cannot really grow very much by only
accumulating more and more new knowledge. It must also develop new and
better ways to use what it already knows. That's Papert's Principle:
Some of the most crucial steps in mental growth are based not simply on
acquiring new skills but on acquiring new administrative ways to use
what one already knows."
The process by which change is altered is the larger target of
evolution. The evolution of evolution does not mean merely that the
mutation rate is evolving, although it could entail this. In fact, the
mutation rate is remarkably constant over time throughout not only the
organic world but also the world of machines and hyperlife. (It is rare
for mutation rates to go above a few percent and rare for them to drop
below a hundredth of a percent. Somewhere around a tenth of a percent
seems to be ideal. That means that a nonsensical wild idea once in a
thousand is all that is needed to keep things evolving. Of course one in
a thousand is pretty wild for some places.)
Natural selection tends to maintain a mutation rate for maximal
evolvability. But for the same advantage, natural selection will move
all parameters of a system to the optimal point where further natural
selection can take place. However that point of optimal evolvability is
a moving target shifted by the very act of reaching for it. In one
sense, an evolutionary system is stable because it continually returns
itself to the preferred state of optimal evolvability. But because that
point is moving -- like a chameleon's colors on a mirror -- the system is
perpetually in disequilibrium.
The genius of an evolutionary system is that it is a mechanism for
generating perpetual change. Perpetual change does not mean recurrent
change, as the kaleidoscope of pedestrian action on a street corner may
be said to endure perpetual change. That's really perpetual dynamism.
Perpetual change means persistent disequilibrium, the permanent
almost-fallen state. It means change that undergoes change itself. The
result will be a system that is always on the edge of changing itself
out of existence.
Or into existence. The capacity to evolve must be evolved itself. Where
else did evolution come from in the first place?
If we accept the theory that life evolved from some kind of nonlife, or
protolife, then evolution had to precede life. Natural selection is an
abiological consequence; it could very well work on protoliving
populations. Once fundamental varieties of evolution were operating,
more complex varieties kicked in as the complexity of forms allowed.
What we witness in the fossil record of Earthly life is the gradual
accumulation of various types of simpler evolutions into the organic
whole we now call evolution. Evolution is a conglomeration of many
processes which form a society of evolutions. As evolution has evolved
over time, evolution itself has increased in diversity and complexity
and evolvability. Change changes itself.