Richard Schroeppel <rcs@CS.Arizona.EDU> wrote:
> Replication is supposed to happen without the help of enzymes.
> The schemes have no place for metabolism or partition into cells.
> Protein translation is relegated to later evolution.
>
> I'd have to reconsider my opinion if someone actually came up
> with test-tube examples of autocatalytic "life". Obviously it
> doesn't have to be RNA, or protein, or polysaccharide, or even clay:
> if we had any example of an evolving replicator, it's much more
> plausible that it evolved to new technology.
Are you aware of how crystal structures grow and produce more crystals? I don't know if this is an example of what you're asking for, but it is a great example of how simple structures can grow and reproduce very quickly, with the "more organized" structures being more likely to form than the "disorganized" structures.
Imagine little microscopic cubes of salt bouncing around in a solution. They are randomly sticking together and breaking apart. They are not too sticky, such that they are permanently glued together, but they are not to unsticky that they always bounce apart.
Sometimes the cubes randomly touch perfectly aligned such that an entire square side is right against another square side. When they stick like this, they form a larger crystal that perfectly lined up. This perfect alignment is much rarer than the random alignments, but sometimes it happens.
More often, the cubes randomly touch in an imperfect alignment such that only part of a square side is touching the other cube. Some will randomly stick half-on and half-off another cube. In this case, the surface area that is stuck together is half that of the perfectly aligned cubes above. Their sticking power is half that of the cubes above.
The more perfectly aligned a cube is when it sticks, the more of its square side is stuck to the other cube. The more surface area that is stuck, the more likely it is to stay together. The better-aligned cubes are much more likely to stick together than the poorly-aligned cubes. By randomly bouncing around, cubes are more likely to line up in rows and columns, forming larger cubes, than they are to stick randomly and form noncubic structures. Like magnets aligning themselves up when stuck together, these cubic crystals will line up and construct larger crystal cubes just by chance. These cubes grow longer and larger, until the large structures can't hold their own weight, and pieces break off to start new cubic structures.
This happens relatively fast. This is not the slow random chance that the crystals will happen to fall together in a big block. This is the fast self-assembling nature of sticky cubes. They naturally fall into self-arranged patterns of organization just like coins naturally fall on one side, but rarely on their edge, because they are much more likely to do so.
This example has cubic structures being formed by cubes that are sticky on all six sides. For molecules that are not cubic, but say hexagon, with stickiness around the edge but not the top or bottom, they will tend to stick together in a plane, forming membranes rather than lumps. DNA and RNA are string-like structures, only sticky on the very ends. It is easy for molecules to add on the end and grow the strings, but breaking apart the middle is much less likely to occur.
Contrary to popular belief, random chance with molecules is not like shaking a box of cards and having them fall together in a card-house structure. It is more like shaking a box of magnet cubes, and having them stick together.
-- Harvey Newstrom <mailto:harv@gate.net> Author, Engineer, Entrepreneur, <http://www.gate.net/~harv> Consultant, Researcher, Scientist. <ldap://certserver.pgp.com>