> From: Alexandra Bilak <email@example.com>
> In Tuesday's seminar, we started off by asking ourselves what
> evolution was, and agreed on the simplified definition that evolution
> implies the passing on, over the years, of "recipes" for a successful
> survival of a species.
Not quite: evolution is the passing on of recipes that are successful in
passing on recipes. There is no "survival of the species" in evolution.
There is survival of individuals (survival machines): A species is not
alive, any more than a football team or a chocolate company is alive. It
is individuals who are alive, hence individuals who "live on" (survive).
But the entity of interest for Dawkins is the gene; it is the gene that
is a recipe: a recipe for doing things that make the "vehicle" of that
recipe (the survival machine) successfully pass it on to the next
> This process of Natural Selection is thus a
> causal one, since successful members of the species will be selected
> and "kept" throughout history, whilst unsuccessful ones will simply
All members of species die; so that isn't the point. But some die with
and some die without passing on their genes. Whatever it is that the
gene codes for, that makes its vehicle successful in reproducing, that's
what is successful.
> We pointed out that there were
> several ways in which organisms reproduce themselves, either by
> cloning, or fission, or, by far the most successful, sexual
> reproduction. If we accept then that it is the successful genes that
> are passed on (and it is important to know that genes control
> development, act as a type of "coding mechanism" determining an
> individual's phenotype), one can say that an organism is merely a
> vehicle used by a gene to embody its success. Indeed, Natural
> Selection favours replicators that will be good at elaborating
> survival machines.
Completely correct. (So the previous paragraph must have been a verbal
muddle, if here you get the point right using different words.)
> EEA, Environment
> of Evolutionary Adaptiveness
Environment of Evolutionary Adaptedness.
> human behaviour can be understood by
> looking at proximal and distal causes; distal causes representing
> behaviour originally shaped millions of years ago by conditions at
> that time, and proximal causes representing novel adaptations to a
> more complex way of life.
The distal (or ultimate) cause of a trait is whatever it was in the EEA
that made the survival machines of genes coding for that trait more
successful at reproducing than its competitors. The proximal mechanism
(then and now) is that we crave sugar because it tastes good (not
because it helps us escape predators in a low sugar-world: That was only
true in the EEA. But it was the EEA that favoured the genes that made us
feel like eating sugar.
> "an ESS is a strategy,
> which, if most members of a population adopt it, cannot be bettered
> by an alternative strategy"
> As a simplified example...
> if we take two different fighting
> strategies in a population of a particular species-say, HAWK and
> DOVE-, it is interesting to see how throughout time and different
> environmental conditions, hawks and doves will both alternatively
> represent evolutionarily stable strategies.
An ESS can be stable because (1) eventually every gene adopts it and no
gene can do better, or (2) because the population oscillates between
conditions when one gene is stable and then another (as in Hawk/Dove);
or (3) because the same individual has genes that code for both, and which
one is active depends on the conditions (spacious/crowded,
plenty/scarcity, high/low predation, etc.) All three lead to a stable
outcome that cannot be "invaded" by another strategy.
> The ESS theory can also be applied to human pacts, for
> example in the case of price-fixing. A price is set for petrol (for
> example) at a high value, being in the interests of all garage owners
> of a population, and thus representing a stable strategy, because it
> corresponds to a general conscious decision. If someone was to
> suddenly decide to lower prices, everyone would be forced to follow,
> thus breaking the "pact".Even in human affairs, then, stable
> strategies are prone to collapse because of treachery from within.
Not quite. A stable strategy won't collapse. Because it can be bettered,
price-fixing is no a stable strategy -- and of course it's no kind of
EVOLUTIONARY strategy, because this is just an analogy. Both evolution
and economics are areas where game-theory (which is what the ESS concept
is based on) can help to explain.
This archive was generated by hypermail 2b30 : Tue Feb 13 2001 - 16:23:08 GMT