Imagine that we have a grass species that lives on a plain. When one of
these grass plants produces seeds, they fall within a quite small circle
around the parent grass plant. Each individual grass plant lives its life
at or near the spot at which it began life, and then, if it lives long
enough, it reproduces, and it's offspring live either at the same spot or
quite nearby. Imagine also that not all parts of the plain are habitable
for this grass, but that there is no way beforehand for a grass plant to
know which are and which are not habitable, so all seeds simply end up in
some location and then are either allowed to reproduce or it is
mysteriously killed off. Thus, there might be a large circular area where
there are no living grass plants because all the ones that set up shop too
close to it (in a band around it equal in width to the distance the seeds
are spread from the parent grass plants) die without having any offspring
that might try to live inside the circle.
Now imagine that the plain has many areas where our grass cannot live, but
that, from their starting point many generations ago, they have still been
able to spread out widely over the plain, even though the areas where they
can't live have sometimes shifted, killing off large populations in some
cases, and sometimes opening new areas of safe living, into which
successive generations of the grass landed and grew, spreading a little at
a time over the now-habitable area. From an airplane, we'd see, in several
directions around the point where the original grass plant started many
generations ago, a sprawl of areas of grass and of areas where no grass
grew. In a speeded up "movie" taken from above, over many generations, we'd
see both expansion at the edges and some shifting where areas that had once
been habitable became inhabitable and where new areas of habitability
opened up.
And just inside the edges of many of the *non*habitable areas that had been
around for any time, there would typically be a band of dead grass or dead
grass seeds, where grass plants just *outside* the area had dropped some of
their seeds just inside the boundary.
This whole setup is a kind of metaphor for my view of evolution, in which
each location on the plain represents a different genome, and these genomes
may find themselves inside an area where they can live, or inside (for a
while) an area where they can't live. At the boundaries of the areas where
they can't live, there are often genomes that will keep "trying" to have
offspring that *can* live inside such areas. This will appear as a band of
"fuzz" on a map, as genomes appear inside the area and then are removed.
Of course, the genome, in this case, has only two genes, one for each
dimension of the plain, but it can have many different alleles, as long as
the new alleles are only slightly different from the parent's alleles of
the corresponding genes.
Thus, because of the two-dimensionality of the genetic specification, we
cannot get what we would normally consider to be a high degree of
complexity in the genomes.
Or can we? In principle, we can still get some interesting results. For
example, one allele might specify a location equal to 3.14159 (pi) inches
south from the point where the first genome appeared on the plain, and the
other might specify a location 2.71828 (e) inches west from the "founding"
seed.
Well, okay, but you get the point.
One nice feature of this metaphor is that it can be translated into a
simple computer program that draws dots on a plane (instead of a plain),
each dot representing a particular pairing of different alleles for the two
genes. By varying both the way the uninhabitable areas are determined, and
their changes over time, I think we'd have a fairly good way of presenting
the basic idea of naturalistic evolution to novices, and perhaps even a way
to do some useful research.
Obviously, the technique could be expanded to three dimensions, though
displaying it on a computer screen would be more difficult. Additional
"dimensions," such as color and intensity could also be added without
making the result non-visualizable. We could also introduce some randomness
so that *some* "seeds" dropped even in habitable areas would be killed off
and occasionally a seed dropped inside a non-habitable area would survive
for a while.
Interestingly, depending on locations and shapes of habitable and
nonhabitable spaces, we could get speciation, where the dots spread into an
area and then became cut off from their ancestors as a nonhabitable area
expanded between them and their ancestor dots. In fact, good sized
populations of dots could become completely cut off from their ancestor
dots, with no longer any way by which the ancestor dots could gradually
shift "genetically" to become members of the new population because the
nonhabitable area would be too wide for the allowed range of
single-generation variations to cross.
Further, in principle, we could add completely non-visible "genes" to the
"genome" of each dot, so the dots could *do* things, such as eat other
dots, or take resources away from nearby dots, or even from dots of other
"species" (remember, the dots only represent location in an abstract
"genetic space"; two dots *widely* separated in genetic space might live
adjacent to each other as two completely different *species* in the
corresponding real space). By adding, or by allowing the "genes" themselves
to add, new "genetic dimensions," I suspect we could get some *very*
interesting results. Selection criteria could be as complex as we like, or
they could depend on the values of multiple "genes," so that, for example,
the mathematical product of two genes might partially determine whether a
dot lives or dies, etc. Since the real world is vastly more complex than we
would be able to make the computer environment with most modern technology,
it is unlikely that we could impose selection criteria any more complex
than those of the real world, but by making them as complex as we wished,
we could watch how the genomes evolve to take advantage of new open
"spaces" and how existing ones died off as such complex criteria changed.
Anyway, if we allowed enough ultimate flexibility in the "genes," we should
see what we see in the real world, but in an abstract way: Each organism's
genome reflects the evolutionary history of the organism and its past
environments. Thus, if the environment does not allow a certain pairing of
two alleles from two sites, but does allow others, we will see this
reflected in the statistics of the existing genes (there will be only
occasional active pairings of the "forbidden" genes from genetically nearby
"permissible" gene pairings). Allowing for this statistical "fuzz" at the
boundaries, each surviving genome will contain a significant amount of
information about the "organism's" evolutionary history. If the selection
criteria remain constant for a long enough time, each genome will be a very
good, but accidental, reflection of its total current environment as well,
because, in this case, the past environment and the current environment
will be the same.
If there are available niches of increasing complexity allowed by the
selection criteria, then any genetically adjacent "organisms" will start
spreading (genetically) into these niches (I'm so far assuming nonsexual
reproduction). That is, as long as there is a "pathway" of ecological
niches from simple to complex, some of the organisms will continue to
evolve along this pathway into greater and greater complexity. As long as
there is benefit in increasing complexity, complexity *will* increase.
Further, at no matter *how* we set the specification of complexity, if
there is a viable pathway of small genetic steps to get to it, some
organisms *will* get to it in time. This includes, of course,
Schutzenberger's "functional complexity," Dembski's "specified complexity,"
and Behe's "irreducible complexity."
They will get there *if* there is a good pathway and if the next small step
along the pathway is open (i.e., habitable to the organism) at times when
that small step occurs genetically. The pathway might not even exist
initially; it only needs to open a little at a time, and even then, it
might do so in fits and starts. Put another way, if an area of habitability
on the hypothetical plane moves slowly enough that it can always have a
genetic population within it, then no matter *where* on the plane it
eventually ends up, descendants of that population will be *in* that area,
no matter what genetic complexity it represents. Thus, if, in space and
time, there has always been, for 3.8 billion years, at least one
continuously-existing habitable area that has been on the way from the
earliest life to the complexity of today's humans, and if it never moves so
fast that the population within it is killed off, then that population will
eventually reach a human level of complexity. "Irreducible" complexity
might take longer because it might have to be reached indirectly, as the
zone of habitability moved (or spread).
But, *unless* there is something *prevent* this, such as extreme bias
against complexity in the variation process or very severe restrictions on
populations (and thus on the number of variations that can be tried), it
*must* eventually reach a great many niches, including niches "for"
extremely complex genomes. They won't, in general, be genetically like our
genomes, but they can be ecologically very much like ours, with the same
degree of "specified" complexity, and the same general levels of
"irreducible" and functional complexity in both genome and resulting organism.
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