(1) THE PRIMEVAL SOUP
The prerequisites for life on earth were:
a) The existence of certain kinds of atoms
b) The presence of energy, ultimately from the sun.
Atoms did not 'exist' in the sense that they had conscious
experience of 'life', they just were: solitary units devoid
of any experience, although presumably they had some
continuance of being. [Are quarks and other such constituents
of atoms immortal, or are they subject to decay?].
The excitation of these building block atoms, caused by
exposure to an energy source (that of the sun or perhaps even
lightening) presumably lead to the atoms adopting their
simplest collective form: that of invariant patterns or
STABLE STRUCTURES. It is assumed that these stable structures
took the form of chains of building block atoms,
0-0-0-#-#-0-# (symbolic chain of atoms)
and that single free floating building block atoms had a
natural affinity towards building block atoms of the same
kind (or perhaps, in some cases, of the opposite kind.
(same kind attraction)
| | | | | | |
0 0 0 # # 0 #
Thus attraction and coupling of 'same-kind' building blocks
led to the development of larger more complex, STABLE
Perhaps due to chance (or perhaps due to the larger molecules
becoming gradually unstable) divisions began to occur within
molecules. 'Splits' occurred in such a way that one molecule
became two individual chains: each chain being an exact
copy of the other.
0-0-0-#-#-0-# (Chain 'A')
| | | | | | |
| | | | | | |
0-0-0-#-#-0-# (Chain 'A1', exact copy of 'A')
In this way, chains become REPLICATORS: that is they
re-created the properties of self.
Duplication had no driving force; the building blocks did not
CHOOSE to replicate. Replication ultimately derived through a
combination of chance and environmental factors which perhaps
shaped this "evolution"; e.g. the presence of energy and the
effect of gravity (and other chemical and physical forces)
upon molecules and their constituent parts.
The fact that replication occurred and continued to occur, was
because it was STABLE. The stable survived because it had
stability. Unstable molecules were unsuccessful because of
their instability i.e. they failed to replicate and hence
failed to continue to 'exist'.Only the stable survived to
replicate again. Only the successful succeeded. Thus, as
Dawkins speculates, the earliest form of natural selection
was simply a selection of stable forms and the rejection of
unstable ones. Indeed, this is true of natural selection
throughout time as "selection of the stable" is surely
equivalent to "selection of the successful".
The survival of molecules depended on their successfulness at
duplicating themselves. Molecules that faithfully produced
replicas of themselves ensured the survival of that molecule
"type' [the successful configuration of building blocks] into
the next 'generation' of replicators. I.e. should the
molecule that produced the duplicate molecule decay, the
molecule type would still be preserved in the form of the
"younger' duplicate molecule. [This is assuming that
environmental factors remained stable]. In this way
successful configurations of building blocks may be seen to
have achieved immortality.
Replication also resulted in VARIATION . Rare copying errors
which were stable (i.e. successful) increased diversity
within the "replicator pool". The success of the replicators
led to increasing demand on the smaller solitary building
blocks. Competition resulted. Once again, this competition was
devoid of any emotion or any "conscious competitive drive".
Molecules which happened to be more stable survived. In fact,
one can assume that the more successful variation increased
their own stability at the expense of other replicators. Such
replicators were selected simple because they were more
successful and hence, survived to replicate again.
Dawkins views stability, and hence success, as having three
Longevity: molecules that survived to reproduce must
Fecundity: molecules that replicate rapidly tend to
become more numerous and hence have a
larger proportion of replicas entering the
3.Copying Fidelity:Molecules that copy themselves accurately
guarantee their own molecular structure's
survival into the next generation.
Incidentally, larger molecules formed more rarely presumably
because they became more unstable. In the tutorial, Gianni
asked why didn't molecular structures continue to grow bigger
rather that replicate. Stevan reminded us that we must
consider environmental constraints, such as the effect of
gravity on a large mass, and spatial constraints. Is it also
possible that such "super molecular structures" could
eventually be subject to decay? Replicators have the
advantage of being able to ensure their survival into the
next generation of replicators. Super-molecular structures
would have to replicate at some point in order to survive.
Furthermore, the replicator is a STABLE STRUCTURE: it is is
successful. Therefore, why should natural selection 'favour'
larger, more unstable, and hence, less successful molecules?
("Favour" here means "a process of AUTOMATIC SELECTION
between rival molecules by reason of their longevity,
fecundity and copying fidelity". Definition taken from
(2) WHAT IS A GENE?
G.C. Williams defines a gene as being "any portion of
chromosomal material that potentially lasts for enough
generations to serve as a unit for natural selection".
A gene then, is in effect, " long-lived" stable replicator,
which through the process of " self replication" ensure the
survival of the gene form into the next generation. As such,
a single gene IN ITSELF is not immortal. Immortality is
achieved through a continuous process of exact replication
through successive generations. I.e. the gene must produce
a faithful reproduction of itself before its "death", and the
younger replica must produce a faithful reproduction of
itself before its death and so on.
As such these replicators are the rational for existence,
since the existence of genes themselves is a consequence of
their success at existing (or surviving). As such, the gene
may be viewed as being the "unit of hereditary"; the most
important factor in evolution.
Just as the replicators are the rational for survival, genes
that are rational behind the survival machine or body.
Animals exist solely as vehicles for the transportation of
genes from one generation to the next. Such vehicles were
"favoured" by natural selection because they successfully
enabled replication of genes . Therefore, their particular
programming, which is contained within the genes survived.
It is logical that genes ( the rational for survival
machines) have become in effect inseparable from the survival
machines they programmed. Vehicles for survival seem to almost
be an extension of the gene, to be used like a tool, to reach
their own selfish ends i.e. reproduction and immortality.
I have perhaps incorrectly personified the genes here. Note
that the selection of vehicles is solely due to their
successfulness in their environment, and their ability to
carry successfully the replicators.
Survival of the genes ( and hence the programming for the
vehicle) rest solely on how successfully they are at
replicating. If they reproduce unsuccessfully they fail to
exist. Only the successful succeed.
At first glance, selfishness of the gene may be called into
question as genes co-operate within the individual e.g.
"building a leg is a multi gene co-operative enterprise".
However, co-operation between genes, still serves the process
of bringing about a single gene's own selfish end, that of
replication. Genes that HAPPEN to co-operate in order to
produce something that HAPPENS to benefit survival are more
likely to survive and therefore be preserved through copies,
through successful generations.
What makes a Gene Bad?
A gene may be shown to be "bad" if it ids consistently
unsuccessful; that is copies of the original gene always
happen to be in a vehicle which fails to succeed. It is
unlikely that a would be successful gene will always happen
to share a body with unsuccessful genes. In the same way, it
is improbable that a replica that always happens to be in a
body that perishes is simply unlucky. It is much more
probable that the gene is a bad gene. Ultimately a gene is
bad because it is unsuccessful i.e. it perishes.
What makes a Gene Good?
The gene which happens to be good at cooperating with other
genes in the gene pool will be more likely to survive and
duplicate [gene pool = the long term environment of the
gene]. As such, genes tend to be favoured by natural
selection if they tend to work well in their environment.
This includes making use of other genes in the gene pool.
Such genes are more likely to survive. Ultimately a goo gene
is "good" because it is successful: since nothing succeeds
There are two other properties of genes that Dawkins suggests
and that I would like to highlight, although both may be
inferred from the above text.
(a)" A gene is either definitely present or definitely absent
in the body of an individual". That is to say a gene either
survives to be carried in a vehicle, or it perishes.
(b)" A gene is no more likely to die when it is a million
years old, than when it is a hundred years old". The life of
a gene is dependent on successful replication in order that
copies may exist in the NEXT generation. (This is also
dependent on stable environmental conditions). The age of a
gene's hereditary line is of no significance to natural
selection. Genes are automatically selected by reason of
their longevity, fecundity and copying fidelity i.e. their
stability or successfulness.
TINY INFLUENCES WITH BIG CONSEQUENCES
Small influences may have a major impact on the likelihood of
the gene becoming more numerous or less numerous in the gene
pool. Anything that compromises the genes welfare decreases
the chances of that gene's survival even when the effects
seems to be minimal.
Dawkins speculates that "tiny influences on survival
probability can have a major impact on evolution: this is
because of the enormous time available for such influences to
make themselves felt". Is Dawkins speaking about
environmental influences shaping evolution rather than
genetic influences affecting survival probability? I presume
that he is, since surely the selection of a single gene
takes place at replication and presumably not over a long
period of time. (Although the amount of time which it is
transported in a vehicle may span decades). If the replicated
gene is successful it is selected (since only successful
genes survive and so enter the next generation). Surely then,
uncertainty about whether a gene will be selected, and hence
uncertainty about what effect it will have on survival and
evolution, could not possibly span across generations. Even
recessive genes are selected to be carried in their vehicles.
SENILE DECAY AND OLD AGE DISEASES
In the tutorial, Liz asked why late acting diseases should
exist in the gene pool since they decrease longevity.
Genetically triggered old age diseases exist in the gene pool
because they are LATE ACTING. Once reproduction has occurred,
the genes have ensured their survival into the next
generation: this is the purpose of survival machines, to
allow the duplication of the genes that they carry. Since the
rational behind existence is replication, natural selection
is blind to late acting lethal or semi-lethal genes;
successful replication has already occurred ensuring gene
survival. What happens to the vehicle after reproduction is,
in effect, irrelevant. As such, genes which are successful
tend to build survival machines which do not die before
reproduction, since machines that decayed before reproduction
would fail to produce replica genes and thus would be
EVOLUTIONARY STABLE STRATEGY: ESS
Maynard Smith defines an ESS as being " a strategy which, if
most members of the population adopt it, it cannot be
bettered bay an alternative".
Dawkins defined an ESS as being " a strategy that does well
against copies of itself. A successful strategy is one that
dominates the population. Therefore, it will tend to
encounter copies of itself. Therefore, it won't stay
successful unless it does well against copies of itself".
An ESS is a strategy which cannot be upset by gene
mutations. In the tutorial we used the "poker face" as an
example of an ESS. The poker face is an ESS because it gives
nothing away. Submission to the opponent is SUDDEN AND
UNPREDICTABLE. Hence, it does well against copies of itself,
it is successful: it is stable.
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