CMR wrote:
>Indeed. The constraints to, and requirements for, terrestrial life have had
>to be revised and extended of late, given thermophiles and the like. Though
>they obviously share our dimensional requisites, they do serve to highlight
>the risk of prematurely pronouncing the "facts of life".
>
>
>
Just to be mischievous, I'll here pronounce "the facts of life" or more
precisely
"a sketch of a theory of the emergence of life" which will serve the
purpose of partially constraining/
defining what is meant by life. This is a hobby project.
The Emergence of Life Via Weak (Stochastic) Physical Pattern Replication
==================================================
Definitions:
"pattern" a form of order or regularity, which can be described by a
finite and usually simple set of constraints.
"living organism" is a subtype of "spatially organized pattern of matter
and energy with some
distribution for a time period in some spatial region" in otherwords, of
"physical pattern in space-time".
"ecosystem" or "supporting environment of an organism" is also a subtype
of "physical pattern in space-time".
"species" is also a subtype of "physical pattern in space-time", ranging
over a larger span of time than an
organism pattern, and which includes instances over time of the
subpatterns of the "species" pattern
that constitute the individual organisms of the species.
Abstract:
---------
The natural selection process that results in the evolution of lifeforms
as we know them can be extended
backwards in time further than is traditionally assumed, to fully
explain the emergence of life from
chance-occurring patterns of matter and energy. A model of the form of
this earliest natural selection
process is presented, in terms of three specific weakenings of the
self-replication and metabolism processes
that lifeforms exhibit.
Characteristics of a living organism:
-----------------------------------
1. It self-replicates (aka reproduces).
Part of what this means is that the organism assimilates surrounding
matter and energy so that
they become part of its species pattern, if not necessarily of its
own "individual organism" pattern.
2. It metabolizes. It ingests matter and energy and converts them to a
form more directly usable for the maintenance
of the form and function of the organism pattern and for its reproduction.
3. It is an autonomous agent (within some environmental constraints.)
The matter and energy that is "inside" the organism pattern can
replicate the pattern, and metabolize
pattern-external matter and energy, in a relatively diverse set of
surroundings, compared to its own form and function
constraints anyway, and it can do these things substantially "by itself"
so long as an appropriate supporting environment
(which may not itself qualify as an organism but has some form and
function constraints itself)
is maintained near it. In a sense, this "autonomous replicating and
metabolizing" criterion just helps us
define a boundary around what matter and energy is "the organism" to
and what is "its environment".
Thesis
-------
1. Before there was "strong" "individual-organism" self-replication,
there was "weak" (stochastic) replication
of "weakly constrained" (and possibly physically dispersed)
"pre-organism" patterns of matter and energy.
The only property (constraint on form and function) that these patterns
had to exhibit was just enough
probability and frequency of just as roughly accurate pattern
reproduction so as to maintain the
order (i.e. the pattern constraints) of the "pre-species" pattern
against the various forms of pattern-dissolution
attacks that occurred in its environment. These attacks don't need to be
explained much. They are comprised
just of
a.. the natural tendency of any physical system to increasing entropy
(disorder) and
b. active processes of dissolution of the pattern or its resources in
its supporting environment where those active
processes are the result of the actions of competing weakly-replicating,
weakly-metabolising physical patterns in the
vicinity.
2. Before there was "strong" "organism-internalized" metabolism
process, there was "weak" (stochastic)
pseudo-metabolism. That is there were processes of energy conversion
(and temperature regimes and
matter mobility regimes (e.g. liquid phases) ) IN THE VICINITY OF A
WEAKLY REPLICATING PATTERN
which were such as to support the (at least probabilistic) carrying on
of the weak replication process
of the pattern. That is, early metabolism could be defined as happening
both within and in the environment
of the pattern. Since the weakly replicating pattern initially may have
been somewhat spatially distributed, and
only stochastically present at various time intervals, it's just as well
that we don't require that the pattern-supporting
energy conversion processes (heat-engine processes) be carrried out
initially entirely WITHIN the pattern (pre-organism)
itself.
Weak Replication and Weak Metabolism Concepts
----------------------------------------------------
Definition-weakening 1 : SPARSE-PATTERN MATTER/ENERGY ACCRETION AS A
PRECURSOR
TO SELF-SUFFICIENT-UNIT SELF-REPLICATION
-------------------------------------------------------------------------------------------------
The minimal criterion for a self-sustaining physical-pattern-accretion
process (or pattern self-replication process) is that
over time, and stochastically, more matter/energy be assimilated into
(become governed by) the constraints
of the pattern (i.e. the form and function of the pattern) than the
amount of pattern-dissolution (pattern information-loss)
that happens via the several processes of
a. inevitable physical system entropy increase,
b. surrounding environment physical accident (part of a. really),
c. competition (for matter/energy organization) from other patterns
(e.g. being eaten by a predator or starved out by a competitive feeder).
Present-day species patterns accrete surrounding matter and energy in a
very specific way. The
species patterns have separate, discrete "individual organism" units
(and individual cell units). These sub-patterns of the whole)
independently replicate (and metabolize). This architecture provides
robustness of the overall pattern-accretion-process against pattern
dissolution. If a disastrous environmental
change happens, there's a good chance only some and not all of the
replication-and-metabolism
units of the pattern will be destroyed. So the information in the species
pattern (that comprises the pattern, you could say) has little chance of
being lost by accident.
An obvious weakening of this "individuation and
self-sufficient-unit-replication process
is a single holistic, and yet possibly spatially dispersed and sparse
physical pattern with the property
that it accretes or assimilates surrounding matter and energy into
itself. However, in this weak pattern
replication process (or more generally, pattern-accretion process), the
spatial and temporal distribution of the matter-energy
accretion need not be organized into discrete, complete replication
events for
individual-organism or individual-cell units. More generalized,
spread-out in space-and-time,
and stochastic matter/energy accretion will do.
When the probability and rate (in some spatial region (some
environment), for some time period, of pattern-accretion
on balance exceeds the rate of pattern-information-loss, and is great
enough that the amount of pattern-information
in the region never becomes zero again, the pattern has achieved
survival-threshold replication ability.
While an individual-unit complete-replication process has obvious
net-accretion-success-probability benefits, and would
thus likely be selected for in an ongoing natural selection process of
pattern versus pattern
competition and pattern vs. environmental-accident competition, the
accretion process need not start at this
level of sophistication. Simple sufficient-rate matter/energy accretion
to pattern-governance is sufficient for there
to be some chance of pattern survival long enough for the pattern to be
improved (and "robustified")
by natural selection in its environment.
Once a physical pattern reaches survival-threshold accretion/replication
probability, natural selection would also
select for spatial contiguity of form in a weakly replicating/accreting
matter/energy
pattern. The argument is simple. Spatially distributed, sparse patterns
are more disruptable, dissolvable into
entropy, by environmental disruption/change occurring partially within
or throughout the
pattern (or location where it "weakly" or "sparsely" exists). More
spatially contiguous pattern or order is less
vulnerable to this sort of disruption, provided the pattern's own
structure (matter/energy arrangement) is
inherently resistant to destructive re-arrangement. If the pattern
"glues itself together" (as earth lifeforms and
their organic molecules do electromagnetically) then it will be more
robust if it is spatially contiguous with less
random intervening environment. Spatial cohesiveness and contiguity
then, is a physical pattern trait
that can increase the form-and-function survival probability of the
pattern over any given time-slice.
In a competitive accretion/replication situation, spatially contiguous
pattern forms with increased probability
of longer survival in diverse environmental conditions will eventually
out-accrete/replicate other pattern forms.
Definition-weakening 2: LOW-FIDELITY REPLICATION
------------------------------------------------------------
DNA and RNA in the cells of present-day organisms replicate with an
error rate of 1 / 10,000,000.
However, the weakest possible criterion for
physical-pattern-self-replication-process fidelity is that the
replication produces another pattern instance of some pattern which
shares a survival-threshold
weak-replication ability with the parent pattern. The successor pattern
DOES NOT HAVE TO BE
IN ANY OTHER RESPECT SIMILAR TO THE PARENT PATTERN.
So the subject of the weak-replication process is an EQUIVALENCE-CLASS
OF PHYSICAL
PATTERNS, equivalent ONLY under the constraint all pattern-variants in
the class are able to carry
on some form of pattern-class-survival-threshold replication and (in
concert with their environment,)
pattern-survival-threshold metabolism.
It is easy to see how natural selection would select for physical
patterns capable of higher fidelity replication (matter-energy
accretion into the pattern form and function) processes. Higher-fidelity
replication narrows the
accreted/replicated pattern's equivalence class of successor patterns.
This allows other advantageous traits
about a pattern's form and behaviour to be more rapidly and reliably
accreted (replicated) once they arise
by chance and competition.
Of course the optimum replication fidelity depends on a trade-off
between the need to be able to change the pattern
(adapt) rapidly in response to changing environments, and the need to
safeguard optimized patterns (by efficient, hi-fi
replication) once those optimized patterns are arrived at. Our
present-day rate of high-replication-fidelity combined with
sexual reproduction (adaptive trait mixer/optimizer process) and
radiation-induced or recombination-accident-induced
genetic mutation is just such a process of optimized-fidelity
pattern-replication process.
Definition-weakening 3: ENVIRONMENT-DRIVEN METABOLISM
------------------------------------------------------------------------
The metabolic process is the process by which a replicating/accreting
physical pattern obtains energy to perform
its survival-necessary behaviours, (such as metabolism itself, and
replication/accretion, and more eventually, more
refined processes like mobility, defense, cooperation, and
environment-modification/optimization behaviours)
and the way in which the physical pattern obtains an external supply of
matter to build its form and/or replace
entropically dissolved parts of its form (e.g. dead cells for a
multi-cellular organism pattern, or dead individual
organisms for a species-pattern.)
Present-day organisms guard their metabolic (matter/energy conversion
i.e. fuel-burning or heat-engine processes)
by conducting them almost entirely spatially internally to the pattern,
with only a relatively narrow and specialized
fuel-intake interface of the pattern to the environment (e.g. of
interface - mouths of animals, photosynthetic surfaces of
plants.)
But this is just an optimization of a process that could originally have
operated in a more spatially distributed form,
and with more contributions of process drivers from the inherent
energy/entropy disequilibrium properties of the environment
that surrounds the metabolizing pattern
A concrete example of circumstances for possible weak metabolic
processes (seen as properties of parts of the environment
as a whole) are the undersea volcanic vents on Earth, with supplies of
elemental ingredients for organic molecules,
supplies of rapidly convertible-to-energy fuel (sulphur), and supplies
of energy (the volcanic processes), all churning
together in sometimes physically contained (organization-trapping)
regions (hollows in rocks) in a liquid medium permitting
high numbers of matter interactions and rearrangements and yet not the
too-high, matter dispersing, equilibrium-forcing energies
and excessive degrees-of-freedom of gas-phase environments.
The minimal criterion for a metabolic process to be occurring for a
physical matter/energy pattern is that
a. appropriate levels of work-usable energy (and thermodynamic
disequilibrium) and appropriate forms of matter
are available in the environment patterns of a pattern, and that
b. the combination of the form and function of the pattern and the form
and function of its environment are such that the
surrounding matter and energy can be applied in sufficient quantity,
stochastically, over time, to the
form and function of the instances of the
replicating-pattern-equivalence-class, such that
c. the pattern-equivalence-class can maintain (on balance) its
survival-threshold accretion process/replication process
and its survival-threshold environmentally-involved metabolism process,
overcoming the rate of spontaneous disordering
of the patterns that is caused by the tendency of any physical system to
increasing entropy.
Once an environment-driven or environment-involved metabolic process
gets going enough to support stochastic
accretion of pattern information, it is easy to see how natural
selection would select for more internalized metabolism
processes, for these processes are more protected against chance
disruption of the pseudo-metabolic operation
of the whole surrounding environment (there is less of the surrounding
environment right there in the middle of the
metabolic process, in an internalized metabolic process, so the
internalized process is less at risk from environmental
vagaries.)
Also, by spatially internalizing the metabolic process, more complex,
specialized, self-sufficient, and more energy-efficient
metabolic processes can be physically structured, contained and
protected from a more randomly varying external environment.
So it is easy to see how cell walls (and organism physical-form
boundaries: tissue, skin etc) would be selected for.
With metabolic internalization come other advantages like ability to
specialize the organism's form for survival in
different environments, while maintaining a consistent metabolic process
inside the form. So organisms that can
keep-together in, thrive in, and move to favorable parts of a liquid
environment, for example, can evolve.
-----------------------------------------------------------------------------------------------------------
Appendix A
A Generalized Description of a Specific Lifelike Pattern-Replication /
Pattern Accretion Process
PHYSICAL PATTERN ACCRETION/REPLICATION THROUGH ATTRACTION OF
COMPLEMENTARY FORM
---------------------------------------------------------------------------------------------
When or how can weak pattern-accretion/replication processes occur by
chance in the first place?
Weak pattern-accretion/replication processes can at least
happen in any physical (or informational?) pattern-equivalence-class which:
a. Can (by its physical form and its interaction properties) cause
either parts of itself, or
the surrounding matter (or symbols) to be formed into a COMPLEMENT of
the pattern's form. i.e.
The pattern's form, at least at some times and places, can cause the
formation of a MOLD FOR
ANOTHER OCCURRENCE OF THE PATTERN OR PART OF THE PATTERN.
An example of a form and interaction-property combination which leads to
complement or "mold"
formation, is of course the molecular shape and distribution of
electric charge along the exterior of
organic molecules like amino acids. These molecular shapes and charge
distributions cause appropriate
binding (collection and collation by electromagnetic attraction and
form-fitting in a soup of appropriate
and appropriately mobile atoms and molecular fragments) of complementary
atoms and
molecules, which in some cases, form a complement that in turn can
attract more atoms of the right
kinds to form a copy of the original amino acid.
This kind of replication by form-complement forming requires certain
environmental
regimes of particular combinations of particular types of commonly
available atoms with particular
electrochemical binding and repulsion properties. It also requires the
environment to exhibit a certain
range of thermodynamic disequilibrium (balance between disordering
mobility and energy of atoms
and the need for the atoms and molecules to be mobile and
momentum-carrying enough to bind
and stick to each other. The appropriate thermodynamic disequilibrium
range (temperature range
and surrounding soup viscosity/pressure) is determined relative to the
strength of the electromagnetic
force and gravitational force and the way that the atoms of different
atomic elements exhibit and interact via
these forces.
The work-ready energy balance and binding forces balance must be such
that complementary
molecules can be attracted, bound and organized, but also occasionally
freed-up to attract another
copy of the original form. It may be a fine balance, with relatively few
modes for its existence in our
particular universe with its particular physical laws and available
proportions of various kinds of
matter and coincident energy/entropy regimes.
-----------------------------------------------------------------------------------------------------------
Appendix B
The META-EVOLUTION PRINCIPLE AND ITS IMPLICATIONS FOR THE
FORM OF LIVING ORGANISMS
-----------------------------------------------------------------------------------
The meta-evolution principle (applicable to matter/energy patterns and
perhaps also or equivalently
to evolvable information patterns) runs as follows:
THE CONTINUOUS AND IMPROVING ABILITY TO BE EVOLVED EFFICIENTLY IS A
NECESSARILY
EVOLVED TRAIT OF ORGANISMS/SPECIES EVOLVED BY THE NATURAL SELECTION PROCESS
All living organisms/species, whose form and function come to exist
through the processes
of
a. initially chance alignment/ordering of matter and energy in
appropriate thermodynamic regimes, and then
b. differential-replication/accretion-probability natural selection
have a form (and behaviour regime) in their whole, and recursively in
all of their parts, as those parts are evolved
subsystems, which is subject to the following constraints:
1. The form (and its complementary behaviour regimes) must be functional
(or at least not excessively survival-detrimental)
during the reign of EVERY VARIANT OF ITSELF WHICH OCCURRED DURING THE
EVOLUTION OF THE
TYPE OF ORGANISM/SPECIES.
AND ALSO
2. The form (and behaviour)
must be READILY EVOLVABLE (FUNCTIONAL OR NOT EXCESSIVELY DETRIMENTAL
WHILE SUBJECT TO AND AMENABLE TO AVAILABLE FORMS OF INCREMENTAL ADAPTATION)
during the reign of EVERY VARIANT OF ITSELF WHICH OCCURRED DURING THE
EVOLUTION
OF THE TYPE OF ORGANISM/SPECIES.
At first this principle may seem like some kind of tautology. But I
think it may be profound to some degree
and possibly new.
-------
The only forms that will evolve (while in competition with natural
accident/entropy and with other resource-competitive forms)
will be those forms which are of such a form that they were
survival-advantageous (or not excessively the opposite)
during ALL STAGES of their evolution of form. THIS IS AN EXCEEDINGLY
STRICT DESIGN CONSTRAINT
ON FORMS!!!!
Furthermore, the forms must (throughout their evolution, and if in
competition, then increasingly as evolved),
be explicitly amenable to (increasing the probability of success of, and
likely utility of)
some kind of mutation process which is readily available in either the
environment or the form and function of
the organism/species itself.
-------
This meta-evolution principle could, for example, explain properties
such as the average level (and the ranges)
of viscosity (mobility versus stability of form and function) inside
living cells, and inside living bodies as a whole.
It could explain the tendency of living structures to be built from
increasingly complex (increasingly spatially larger)
layerings or networks of "fractally functional" forms which expand
themselves at their boundaries but retain
overall form constraints with slight variations allowed (a level of
physical pliability/adaptability, both for adaptation
to the immediate environmental problems of the individual organism, but
also to allow a dimension in which a
small, non-destructive form-difference can exhibit and be differentially
reproduced if generally adaptive.
It could explain why sexual reproduction is successful, for while it
varies the forms (leading to adaptation/optimization
for different environmental problems), the variation in form is
constrained to be in forms akin to those (or simple
combinations of those forms) of previously successful examples (two
successful parent organisms) of the species.
----------
Similarly with the evolved behaviours of the evolved forms.
-----------------------------------------------------------------------------------------------------------
Eric
Received on Sun Jan 18 2004 - 03:32:57 PST
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