[net.origins] No Cigarettes, Please

dubois@uwmacc.UUCP (Paul DuBois) (07/23/85)

>>> [Rich Rosen]
>>> What natural selection and evolution "predict" is that, for that set of
>>> circumstances that occurs over a period of time, the organisms that
>>> survive that period will be the ones best suited for those
>>> circumstances, and those of course will be the ones that produce the
>>> offspring that follow into the next period.

>> [Paul DuBois]
>> Rich, this is simply unworthy of you.  They "predict" that fitter
>> organisms will survive?

>> ProFOUND.

> [Mike Huybensz]
> Paul, are you incapable of reading beyond the first clause?

First we need to establish that I can read.  I'm not too hopeful.

> The key part is that the surviving organisms will be the ones to
> reproduce, passing on their characters to the next generation.  Thus,
> the distribution of characters changes over the generations, producing
> a better adapted population.

Yes, yes, grok, grok.

> Of course you can respond "ho hum" to this too; I wouldn't be surprised,
> since it has more than one sentence.

Ok, I won't respond that way, since the problem itself is interesting -
if facile paperings-over of it (like yours) are not.  Your comment
reminds me, though, of a mild lecture I received from you once,
remonstrating with me for (supposedly) engaging in _ad hominem_ attacks.
I guess you don't really mind, since you'll "stoop" to it yourself.  :-)

---

Before going further, let me make two observations about what follows:

(a) I am not trying to bring up a problem just so I can fling it into
the teeth of evolutionists, so don't take it that way.

(b) what follows does not necessarily have anything to do with
evolution (defined as "the production of new organisms from old"), at
least it has nothing to do with it without additional elaboration of
the situation that was described by Rich.  The problem is more general,
and is deserving of more widespread attention from creationists than it
has so far received.

To proceed:
I said "proFOUND" because what Rich said was in a sense obvious.  The
basic idea is quite beguiling, though, and not least because of its
simplicity.  It "does express an idea which seems correct", and it
*does* have a certain charm and beauty, which even I will admit to an
appreciation of, hardcore creationist though I am (and I am).  But I'm
not about to accept it just because it is charming and beautiful.

Ok.  Now, as I said, Rich's statement is obvious; what else would you
(or anyone, even the most ignorant backwoods imbecile) expect?  The
simple statement is:  Fit organisms survive to posterity.  But that,
perhaps, collapses the idea a little too much.  Rich said, somewhat
differently, "What natural selection and evolution 'predict' is that,
for that set of circumstances that occurs over a period of time, the
organisms that survive that period will be the ones best suited for
those circumstances, and those of course will be the ones that produce
the offspring that follow into the next period."  But when we say that,
are we really saying anything?  Not that I can tell.  At least nothing
that means anything.  The statement is more elaborate and subtle than
"survivors survive", but it's no different, really.  We went through
this all several months ago, and while my recalcitrance at accepting
this triviatum seemed to arouse a lot of indignation, no one really
addressed problem.  Neither have you, Mike.  You've dressed it up in
yet another set of words, but they boil down to the same obvious
statement.

In fact, the thing is *so* obvious, I'm inclined to wonder if it is
even right.  After wondering, I don't think it is.  I do not see, for
example, the justification for the functional link made between
reproduction and survival that is used as the criterion of fitness.

What does "survive" in Rich's statement mean?  Presumably not that they
don't die, for all organisms do.  Also presumably not that they
reproduce more, or else the statement reduces immediately to a
tautology that is not interesting.  So it seems to mean "they live
longer than organisms which are not so fit".  (If all this seems
obvious to you, please forgive me.  Console yourself with the thought
that I'm just trying out possibilities to see if I've reached the stage
of formal operations yet.)

So the ones that survive "circumstances" will be the ones to pass genes
to the next generation.  But at this point I start to wonder:  what are
the others doing in the meantime, *before* they die?  Consider
population x, with two subpopulations of organisms x1 and x2.  Organism
type x1 lives until age a1, at which time it drops over dead.  But
during that time it breeds like a rabbit, at rate r1.  Organism type
x2, on the other hand, breeds more slowly, at rate r2, but lives
longer, to age a2.  Let's say the difference is due to a genetic
linkage which results in reproductive acceleration at cost of
lifespan.

That is,
         r1 > r2
         a1 < a2

So x1 leaves a lot of offspring, but does not survive very well
itself.  It breeds a lot and then kicks off.  x2 does not leave many
offspring, but survives much longer.

Which is fitter?

I personally would say x2 because it lives longer, i.e., it survives.
But since x1 leaves more offspring it passes more genetic material to
posterity.  So by definition it is fitter:  it enjoys reproductive
success.  But in fact, all we know for sure is that x1 is more
numerous.  We do not really know if it is fitter.  Its numerosity may
have nothing to do with fitness, except in the trivial sense that
fitness is measured by reproductive success.

We say that the ones that are fit will be the ones that reproduce.  It
would be more accurate to say that the ones that reproduce will be the
ones to reproduce.  They may not be the ones surviving the longest.
Maybe they're good at reproducing and nothing else.

Of course, my own personal choice of x2 is questionable; it depends
what level you look at.  At the level of the group, x1 is fitter; it
propagates more.  At the level of the individual, x2 is fitter; it
survives longer.

Natural selection (now) refers to populations; presumably x1 is fitter
according to that view.  Somewhere in here lurks a problem, which is
(from my point of view) a paradox, and which seems (to me) wrong.  The
paradox (to me) is that x1, the crappy organism (by my standards), is
judged fitter because it satisfies the criterion of reproductive
success better.  A poorer organism produces a fitter population because
of the way fitness is defined.  This leaves me feeling, to say the
leaast, somewhat ambivalent.  Now of course we need definitions, but
not definitions that "solve" problems which should be investigated
empirically.  Here I throw up my hands and "resolve" the paradox by
deciding that the criterion of fitness is worthless.  (I put "resolve"
in quotes because obviously this decision does not advance us very
far.)

The error (as it seems to me) is that the link between survival and
reproduction in assessing fitness is unnecessary, or at least
poorly-defined or wrong.  It *seems* to me (I may be wrong, so no
flames - just point out my error) that the two are tied together in a
way that cannot logically be required:  there is no necessary
relationship between survival of the "fit" individual (measured by
lifespan) and generation of the next "fit" population (measured by
reproductive success).

By saying that the ones that survive reproduce more (that is what Rich
said, and what Mike I think defended), one makes this link.  But on
what basis?  I assume on this basis:  the ones that survive longer,
leave more offspring *all other things being equal*.  I suppose they
will - but why make this assumption?  Things are not obviously equal.
To make the theory work?  Not a chance.  It has to be *shown*, not
assumed.  In my example, it's false.  Its not a thing to be considered
true or false a priori, but something to be *found out*.  Otherwise,
someone can just come along and cook up one of these ad hoc stories
like, "the ones that live for a shorter time will be selected for
maximum reproductive rate, and thus will be at no disadvantage."  Well,
sure.  But so will the ones that live longer.  If we take that route,
the criterion, reproduction, is what gets selected for, not something
else.  We end up with a view of organisms that are adapted *to
reproduce*.  But that was the way they *expressed* their fitness, I
thought, not the thing they were supposed to be fit at doing.

Let us go back a little.

Those which are fitter will leave more offspring
	but only true if fit *to leave offspring*
	or, if fitness *is defined as* leaving more offspring

and then "fitness" is meaningless, because it says nothing.  Try it -
make the substitution of variables:

	fitness = fit to leave offspring, yields
    Those which are fit to leave more offspring will leave more offspring

	fitness = leaving more offspring, yields
    Those which leave more offspring will leave more offspring

Not very illuminating.  Hence my frequent comments in the past about
vacuity.

Let me raise an objection against what I have just written.  As
indicated above, fitness is measured by differential reproductive
success.  Now, at this point, millions of critics have risen up and
cried "tautology!"  One asks, "which are the fittest?"  "Those that
survive."  "Which survive?"  "The fittest."  "Oh..."

But that view *equates* fitness with differential success, and that
is ... (remembernowIamacreationistsoholdyourbreath) ... incorrect!
(Although this mistake is often made, e.g., by evolutionists accepting
too easily the words of their evolutionary mentors.)

As an alternative, it is possible to construct the following view.  I
will try to make my thinking explicit.  First, we must observe that
"fitness is measured by differential reproductive success" and "fitness
is differential reproductive success" are two *different* statements.
If this is kept in mind, the tautology may disappear (I'm not convinced
that it does, but I suspect that it might).

Organisms are or are not fit.  Fitness is the thing we want to measure,
but how do we do it?  We can say that fitness is some abstract
quantity, but which is a covert variable, not directly observable.  So
we need an overt variable that we can hang a number on.  The overt
variable needs to be in some sort of relationship to fitness, and
reproductive success is thought to have that characteristic.  If the
relationship is strong, then we have in differential success a good
indicator of the fitness of the population.  My question is:  how do we
know that differential reproductive success is a valid indicator?  My
answer is that we don't.  It is thought to be so, but I'm skeptical.
Is an increased number of offspring a necessary consequence of
fitness?  I don't think so.

At the very least, our covert variable, fitness, is confounded with
something else, i.e., reproductive *ability*.  Differential
reproductive success is in part or whole a function of reproductive
ability.  I do not think this can be disputed.  It may also be, and
probably is, a function of other factors, among which fitness may well
number.  That is,

	drs = f (reproductive ability, fitness?, ... )

But we certainly do NOT have

	drs = f (fitness only)

If anyone thinks that the latter is true, then I invite you to
demonstrate how we may decouple fitness from reproductive ability, for
that must be done to use differential reproductive success as a valid
indicator.

I think that much of the problem arises from the fact that we don't
really know what fitness *is*.  Everybody has some intuitive idea about
it.  The reproductive stuff is one of them.  Obviously I believe that's
an incorrect intuition, and disintegrates under scrutiny.

But if fitness is defined some other way, e.g., ability to live longer,
then there is no necessary link with reproductive capacity.  And then,
I think, the whole thing falls apart.

We need a new view ("one that won't make my eyes turn red...").  I
wish I had it.  I know I'm better at criticizing than constructing,
and though I think this is constructive criticism of a sort, I haven't
gotten further than the above, so far.

---

Final jab:

It is interesting (to me at least), that creationists are said not to
know what evolution is, and so are consequently said not to know what
they are criticizing.  This is often true, unfortunately.  But I
suspect, more strongly as time goes by, that many evolutionists don't
know what they are *defending*!  Witness the recent posting in which
someone spouted the Darwinian orthodoxy, right down the line, as though
it were considered credible today.  Right out of his high-school
textbook, I suppose.

Witness also the great importance attached to natural selection by many
on this net.  But how important is it in recent evolutionary theory?
Not very, in a number of instances.  Michael Lonetto has shown evidence
that he knows this.  How many others?  Rich is (apparently) still in
the dark ages, carrying this (apparently) *unexamined conviction*
around.  Mike H might be, but I doubt it; I suspect that he was trying
to clarify what Rich said, rather than defend it as his own position.

In any case, what natural selection *is*, how one detects its absence
or presence, how one measures its intensity of effect, are questions
that have all gone largely unanswered and are solved, as far as I can
see, largely by definition.  What we see in the postings are vague
generalizations, or "there's a lot of research on it today".  I am not
satisfied with this, and it would be a shame if anyone else was either,
particularly evolutionists.  I suspect that such comments are
smokescreens, serving as substitutes for thought.  I certainly do *not*
accept the pontifications about it, as if I should just shut up and
believe the (current) revealed wisdom.

-- 
                                                                    |
Paul DuBois     {allegra,ihnp4,seismo}!uwvax!uwmacc!dubois        --+--
                                                                    |
"More agonizing, less organizing."                                  |

throopw@rtp47.UUCP (Wayne Throop) (07/26/85)

It seems that a lot of the discussion in the referenced posting is based
on a misperception.  In particular:

> So x1 leaves a lot of offspring, but does not survive very well
> itself.  It breeds a lot and then kicks off.  x2 does not leave many
> offspring, but survives much longer.
>
> Which is fitter?

There is the implicit assumption that there is a linear scale of
"fitness".  This is a deeply rooted problem that appears in many
places.  IQ, testing for an ominous example.  Resteraunt grading for
another.  After all, which tastes better, Cajun cooking or German?

I would say then that much of what followed is bogus, since it is based
on the notion that natural selection is based on an absolute fitness
scale.  Natural selection is based more on competition for available
resources.

Some other specific points:

> The error (as it seems to me) is that the link between survival and
> reproduction in assessing fitness is unnecessary, or at least
> poorly-defined or wrong.  It *seems* to me (I may be wrong, so no
> flames - just point out my error) that the two are tied together in a
> way that cannot logically be required:  there is no necessary
> relationship between survival of the "fit" individual (measured by
> lifespan) and generation of the next "fit" population (measured by
> reproductive success).

The relationship seems clear to me.  Most organisms cannot (or likely do
not) reproduce at all until a certain age, and then they reproduce for
at some rate *after* that age.  Therefore an organism must first live
long enough to reproduce at all.  Then, the longer-lived organisms will
produce more total offspring, since number of offspring is the rate of
reproduction times the length of time spent reproducing.  Thus, there is
a simple and direct relationship between lifespan and reproductive
success (where lifespan is (perhaps) one component of fitness).

> By saying that the ones that survive reproduce more (that is what Rich
> said, and what Mike I think defended), one makes this link.  But on
> what basis?  I assume on this basis:  the ones that survive longer,
> leave more offspring *all other things being equal*.  I suppose they
> will - but why make this assumption?  Things are not obviously equal.
> To make the theory work?  Not a chance.  It has to be *shown*, not
> assumed.

Nonsense.  This is just what is done in physical systems, such as
relating temperature, pressure, volume, and so on.  The assumption of
"other things being equal" isn't needed to make the theory work.  It
just makes it clear what happens *if the assumption is so*.

If other things are *not* equal, there will still be *benefit* to being
(say) longer lived.

> But we certainly do NOT have
>
>         drs = f (fitness only)

Quite so.  But longevity (what you seem to be calling fitness here)
*does* bestow relative reproductive advantage.

> [...]
> demonstrate how we may decouple fitness from reproductive ability, for
> that must be done to use differential reproductive success as a valid
> indicator.

No it mustn't.  I'm not at all sure what makes Paul think it must.

> Witness also the great importance attached to natural selection by many
> on this net.  But how important is it in recent evolutionary theory?
> Not very, in a number of instances.  Michael Lonetto has shown evidence
> that he knows this.  How many others?  Rich is (apparently) still in
> the dark ages, carrying this (apparently) *unexamined conviction*
> around.  Mike H might be, but I doubt it; I suspect that he was trying
> to clarify what Rich said, rather than defend it as his own position.

I don't follow this at all.  Perhaps some of the enlightened, such as
Michael Lonetto, would let me in on the secret.  In what way is natural
selection unimportant to "recent" evolutionary theory.

> Paul DuBois     {allegra,ihnp4,seismo}!uwvax!uwmacc!dubois
-- 
Wayne Throop at Data General, RTP, NC
<the-known-world>!mcnc!rti-sel!rtp47!throopw

friesen@psivax.UUCP (Stanley Friesen) (07/30/85)

In article <1318@uwmacc.UUCP> dubois@uwmacc.UUCP (Paul DuBois) writes:
>
>To proceed:
>
>What does "survive" in Rich's statement mean?  Presumably not that they
>don't die, for all organisms do.  Also presumably not that they
>reproduce more, or else the statement reduces immediately to a
>tautology that is not interesting.  So it seems to mean "they live
>longer than organisms which are not so fit".  
>
	In point of fact, the real meaning in evolutionary theory
*is* that they reproduce more, even if you think that is an
uninteresting tautology! From an evolutionary standpoint longer life
is only meaningful if it leads to more reproduction. What is actually
significant is extended reproductive success of a genotype. That is
an organism which produces so many offspring that they all starve
has a lower effective reproductive rate than one which only produces
as many offspring as can survive!

>
>Of course, my own personal choice of x2 is questionable; it depends
>what level you look at.  At the level of the group, x1 is fitter; it
>propagates more.  At the level of the individual, x2 is fitter; it
>survives longer.
>
	But you see, evolution operates at the *group*(i.e population)
level, so that *individual* "fitness" is only significant as a
component of population fitness.

>Natural selection (now) refers to populations; presumably x1 is fitter
>according to that view.  Somewhere in here lurks a problem, which is
>(from my point of view) a paradox, and which seems (to me) wrong.  The
>paradox (to me) is that x1, the crappy organism (by my standards), is
>judged fitter because it satisfies the criterion of reproductive
>success better.  A poorer organism produces a fitter population because
>of the way fitness is defined.  This leaves me feeling, to say the
>leaast, somewhat ambivalent.  Now of course we need definitions, but
>not definitions that "solve" problems which should be investigated
>empirically.  Here I throw up my hands and "resolve" the paradox by
>deciding that the criterion of fitness is worthless.  (I put "resolve"
>in quotes because obviously this decision does not advance us very
>far.)
>
	Ah, but you are confusing the scientific concept of
"biological fitness" with the human valuation of fitness. They
are seperate ideas. So you prefer organism x2 - fine! But that
has nothing to do with science, or the *scientific* concept of
fitness.

>The error (as it seems to me) is that the link between survival and
>reproduction in assessing fitness is unnecessary, or at least
>poorly-defined or wrong.  It *seems* to me (I may be wrong, so no
>flames - just point out my error) that the two are tied together in a
>way that cannot logically be required:  there is no necessary
>relationship between survival of the "fit" individual (measured by
>lifespan) and generation of the next "fit" population (measured by
>reproductive success).
>
	Quite true! In fact serious evolutionary theorists make no
such claim! If we did we would have a hard time explaining annual
plants and such like!

>By saying that the ones that survive reproduce more (that is what Rich
>said, and what Mike I think defended), one makes this link.  But on
>what basis?  I assume on this basis:  the ones that survive longer,
>leave more offspring *all other things being equal*.  I suppose they
>will - but why make this assumption?  Things are not obviously equal.
>To make the theory work?  Not a chance.  It has to be *shown*, not
>assumed.  In my example, it's false.  Its not a thing to be considered
>true or false a priori, but something to be *found out*.
>
	Actually, they are simply speaking imprecisely. There is a
demonstrable connection in organisms that reproduce more than once
and/or require time to reach reproductive maturity. An organism that
fails to reach reproductive maturity has left *no* offspring, so
survival longer *can* increase reproduction, and with multiple
reproduction longer life generally allows more reproduction events!
This is still secondary however.

>Let us go back a little.
>
>Those which are fitter will leave more offspring
>	but only true if fit *to leave offspring*
>	or, if fitness *is defined as* leaving more offspring
>
>and then "fitness" is meaningless, because it says nothing.  Try it -
>make the substitution of variables:
>
	Ah, but you are treating fitness as a valuation when it is
a *measure*. That is fitness is the *measure* of how well an organism
does at reproducing itself. The key is to then calculate the *effect*
of leaving more offspring on the genetic composition of the whole
population, the result of this mathematical model is *changed gene
ratios* in which those genes that contributed most to reproductive
success have increased the most. Now apply this repeatedly to each
generation and you have evolution! To show evolution does not occur
youy must now show one of a) solid limitations on variation exist,
b) that gene ratios do not change, or c) that genes do not effect
reproductive success(i.e. fitness).

>	fitness = fit to leave offspring, yields
>    Those which are fit to leave more offspring will leave more offspring
>
>	fitness = leaving more offspring, yields
>    Those which leave more offspring will leave more offspring
>
>Not very illuminating.  Hence my frequent comments in the past about
>vacuity.

	Mainly because such statements have nothing to do with
evolution. The real statement is "Fitness(i.e. reproductive success)
causes increased representation in the next generation of similar
individuals".
>
>Let me raise an objection against what I have just written.  As
>indicated above, fitness is measured by differential reproductive
>success.  Now, at this point, millions of critics have risen up and
>cried "tautology!"  One asks, "which are the fittest?"  "Those that
>survive."  "Which survive?"  "The fittest."  "Oh..."
>
	I repeat, fitness *is* the measure of reproductive success.

>But that view *equates* fitness with differential success, and that
>is ... (remembernowIamacreationistsoholdyourbreath) ... incorrect!

	Exactly! Except that it is correct, by *definition*, since
that is how we biologist define fitness.
>---
>
>Final jab:
>
>It is interesting (to me at least), that creationists are said not to
>know what evolution is, and so are consequently said not to know what
>they are criticizing.  This is often true, unfortunately.  But I
>suspect, more strongly as time goes by, that many evolutionists don't
>know what they are *defending*!  Witness the recent posting in which
>someone spouted the Darwinian orthodoxy, right down the line, as though
>it were considered credible today.  Right out of his high-school
>textbook, I suppose.
>
	Mainly because most of the evolutionary supporters on the
net on not biologists, only laymen with an interest in the subject,
which may often be somewhat of date.

>Witness also the great importance attached to natural selection by many
>on this net.  But how important is it in recent evolutionary theory?
>Not very, in a number of instances.  Michael Lonetto has shown evidence
>that he knows this.  How many others?  Rich is (apparently) still in
>the dark ages, carrying this (apparently) *unexamined conviction*
>around.  Mike H might be, but I doubt it; I suspect that he was trying
>to clarify what Rich said, rather than defend it as his own position.
>
	Actually, it is still *very* important, except among certain
extreme schools of evolutionary thought such as the most extreme forms
of Punctuate Equilibrium and the "neutralist" theories of many
microbiologist(who have little experience with organisms  under
natural conditions).

>In any case, what natural selection *is*, how one detects its absence
>or presence, how one measures its intensity of effect, are questions
>that have all gone largely unanswered and are solved, as far as I can
>see, largely by definition.
>
	Well, I gave a simple definition above. And definition is a
perfectly valid approach to a problem, provided it fits with the data!
Look at how physicist approach the concept of mass. It is simply
*defined* as the measure of resistance to acceleration! Or if you
use the approach you used above for "fitness" this becomes "Mass is
what mass is" by substitution of variables.
-- 

				Sarima (Stanley Friesen)

{trwrb|allegra|cbosgd|hplabs|ihnp4|aero!uscvax!akgua}!sdcrdcf!psivax!friesen
or {ttdica|quad1|bellcore|scgvaxd}!psivax!friesen

keithd@cadovax.UUCP (Keith Doyle) (07/30/85)

.........
>Of course, my own personal choice of x2 is questionable; it depends
>what level you look at.  At the level of the group, x1 is fitter; it
>propagates more.  At the level of the individual, x2 is fitter; it
>survives longer.

It's even more complicated than that.  In an environment where it is
most important to reproduce, then x1 is better, where it is not so
important (maybe overpopulation causes most of them to die anyway)
then they may be on equal terms or even x2 could have the advantage
(perhaps an animal being pregnant might be more succeptible to 
predation for various reasons).

>empirically.  Here I throw up my hands and "resolve" the paradox by
>deciding that the criterion of fitness is worthless.  (I put "resolve"

The criterion of fitness is not absolute, but relative
(to the complex details of the individual environment).
You seem to want to pigeonhole the criteriae for fitness
in some sort of absolute value system.

>By saying that the ones that survive reproduce more (that is what Rich
>said, and what Mike I think defended), one makes this link.  But on
>what basis?  I assume on this basis:  the ones that survive longer,
>leave more offspring *all other things being equal*.  I suppose they
>will - but why make this assumption?  Things are not obviously equal.
>To make the theory work?  Not a chance.  It has to be *shown*, not
>assumed.  In my example, it's false.  Its not a thing to be considered

We cannot assume it is false without more details.  Under some circumstances
x1 is fitter, under others x2.  There is no all pervasive criteria for
judging the fitness of x1 and x1.

>like, "the ones that live for a shorter time will be selected for
>maximum reproductive rate, and thus will be at no disadvantage."  Well,
>sure.  But so will the ones that live longer.  If we take that route,
>the criterion, reproduction, is what gets selected for, not something
>else.  We end up with a view of organisms that are adapted *to
>reproduce*.  But that was the way they *expressed* their fitness, I

Effectively, that is what we have.  However, an immense variety of 
characteristics and conditions can interplay to make up relative
fitness for reproduction.  In addition, various characteristics may
be intertwined with characteristics that have very little to do with
reproduction, thus causing them to be 'carried along' with the more
important selection characteristics.  The basic ability to survive is
intertwined with the ability to reproduce.  The ability to feed oneself
and avoid predation is intertwined with the ability to survive.  The 
ability to keep from freezing in cold climates may be intertwined if
an organism lives in the cold etc.

>Those which are fitter will leave more offspring
>	but only true if fit *to leave offspring*
>	or, if fitness *is defined as* leaving more offspring
>
>and then "fitness" is meaningless, because it says nothing.  Try it -
>make the substitution of variables:
>
>	fitness = fit to leave offspring, yields
>    Those which are fit to leave more offspring will leave more offspring
>
>	fitness = leaving more offspring, yields
>    Those which leave more offspring will leave more offspring
>
>Not very illuminating.  Hence my frequent comments in the past about
>vacuity.

I would say that it in itself is awfully obvious.  Apparently it's
entertwinement with evolutionary theory is where it becomes confusing
(thus the apparent repeated confusion on N.S. and relateds in this
discussion).

>Is an increased number of offspring a necessary consequence of
>fitness?  I don't think so.

Is it a necessary consequence of survival?  Not necessarily, as before,
the number of offspring may have nothing to do with reproductive success.
An organism that only has one offspring but can protect it from predation
better than another organism that has umpteen offspring, may achieve higher
reproductive success.

>At the very least, our covert variable, fitness, is confounded with
>something else, i.e., reproductive *ability*.  Differential
>reproductive success is in part or whole a function of reproductive
>ability.  I do not think this can be disputed.  It may also be, and
>probably is, a function of other factors, among which fitness may well
>number.  That is,
>
>	drs = f (reproductive ability, fitness?, ... )
>
>But we certainly do NOT have
>
>	drs = f (fitness only)

Here I would almost agree.  I would say that drs is equivalent to f, but
that;

        drs = f = (reproductive ability, longevity, fertileness, ability
                   to cope with present environmental concerns, ability to
                   avoid predation,.........)

Only because I define fitness as drs.  Your definition of fitness seems
to be some personal subjective judgement.  You have to ask, fitness
for what?  I would respond, to reproduce.  Perhaps you have a different answer
here.

>If anyone thinks that the latter is true, then I invite you to
>demonstrate how we may decouple fitness from reproductive ability, for
>that must be done to use differential reproductive success as a valid
>indicator.

Valid indicator of what?  DRS is a mechanism for filtering out
harmful (to DRS) mutations, and preserving useful ones.  Sure, DRS=F
dosen't say much, it's ridiculously obvious.  It's effect as a filter
and as an adaptation mechanism is where it all gets interesting.

>But if fitness is defined some other way, e.g., ability to live longer,
>then there is no necessary link with reproductive capacity.  And then,
>I think, the whole thing falls apart.

No, the bottom line is, the ability to produce offspring that survive.
Its just that:

      DRS <> (quantity of offspring)
or
      DRS <> (longevity)
or
      etc....

because there are all kinds of other factors.  In addition, characteristics
that are neutral with regard to DRS, are not necessarily filtered out in 
the process, though they may later resurface and become non-neutral if other
considerations (environment, related characteristics, etc.) change.

>Paul DuBois     {allegra,ihnp4,seismo}!uwvax!uwmacc!dubois        --+--

Keith Doyle
#  {ucbvax,ihnp4,decvax}!trwrb!cadovax!keithd

dsf@allegra.UUCP (dave fox) (07/30/85)

It is not tautological, it is not paradoxical, it is not
vacuous.  It is just very simple:  The organisms we see
around us are those whose parents did not die until after
they were born.

kst@telesoft.UUCP (Keith Thompson @stroke) (08/02/85)

In article <1318@uwmacc.UUCP> dubois@uwmacc.UUCP (Paul DuBois) writes:
> ...
> Organisms are or are not fit.  Fitness is the thing we want to measure,
> but how do we do it?  We can say that fitness is some abstract
> quantity, but which is a covert variable, not directly observable.  So
> we need an overt variable that we can hang a number on.  The overt
> variable needs to be in some sort of relationship to fitness, and
> reproductive success is thought to have that characteristic.  If the
> relationship is strong, then we have in differential success a good
> indicator of the fitness of the population.  My question is:  how do we
> know that differential reproductive success is a valid indicator?  My
> answer is that we don't.  It is thought to be so, but I'm skeptical.
> Is an increased number of offspring a necessary consequence of
> fitness?  I don't think so.
> ...

Differential reproductive success is indeed the key issue here.  
This is, by definition, the *only* indicator of the fitness of a
population.  Specifically, "fitness" is the set of characteristics
that tend to result in reproductive success.  (This is my personal
definition; I don't claim that biologists define the term the same
way.)  What these characteristics are depends on what kind of
environment the organism lives in.  Longevity is certainly one
characteristic that contributes to fitness (the longer an organism
lives, the more time it has to reproduce), but by no means the only
one.  I would say that the common housefly is considerably more
successful as a species than, say, the Galapagos tortoise.

Note that what I have stated so far is a definition, not a (testable)
theory.  What the theory of evolution by natural selection states, as
I understand it, is that there are indeed such characteristics, and
that they can be passed on to an organism's descendants.  In other
words: 
(1) Reproductive success is (at least partially) a result of certain
    characteristics inherent to an organism; it is not purely a result
    of random chance.
(2) These characteristics can be passed on; successful organisms tend
    to have successful offspring (and lots of them).

Note that there is a distinction between fitness and success.  Fitness
is a set of characteristics inherent to an individual or species.
Success is an observable *result* of fitness.  Note that success can
be a result of things other than fitness.  For example, blind luck can
play a significant role.  The more recent "post-Darwinian" theories of
evolution focus on factors other than natural selection.  However,
natural selection still plays a major part (I think).

Given that mutations occur, creating a large pool of different
characteristics in a population, and that some small fraction of these
mutations result in greater "fitness", and thus in differential
reproductive success, how can evolution *not* occur?

Comments appreciated; flames to /dev/null.

		-- The_Other_Keith
--
"Inevitably, their affair ended: Howard worried excessively about what
the pack would think, and Agnes simply ate the flowers."

dubois@uwmacc.UUCP (Risky Rat) (08/05/85)

>> [Paul DuBois]
>> Witness also the great importance attached to natural selection by many
>> on this net.  But how important is it in recent evolutionary theory?
>> Not very, in a number of instances.  Michael Lonetto has shown evidence
>> that he knows this.  How many others?  Rich is (apparently) still in
>> the dark ages, carrying this (apparently) *unexamined conviction*
>> around.  Mike H might be, but I doubt it; I suspect that he was trying
>> to clarify what Rich said, rather than defend it as his own position.

> [Wayne Throop]
> I don't follow this at all.  Perhaps some of the enlightened, such as
> Michael Lonetto, would let me in on the secret.  In what way is natural
> selection unimportant to "recent" evolutionary theory.

I misspoke somewhat.  What I should have said, was that natural
selection is considered unimportant more and more in regard to
*speciation* - not evolution in general.  (My reference to Michael L
was in regard to his posting on speciation in Drosophila.)

Anyway, to clarify, my favorite passage comes from:

    Stephen Jay Gould, "Is a new and general theory of evolution
    emerging?", _Paleobiology_, 6(1), 1980, 119-130.

    The control of evolution by selection leading to adaptation lies at
    the heart of the modern synthesis.  Thus, reproductive isolation,
    the definition of speciation, is attained as a by-product of
    adaptation -- that is, a population diverges by sequential
    adaptation and eventually becomes sufficiently different from its
    ancestor to foreclose interbreeding.  (Selection for reproductive
    isolation may also be direct when two imperfectly-separate forms
    come into contact.) But in saltational, chromosomal speciation,
    reproductive isolation comes first and cannot be considered as an
    adaptation at all.  It is a stochastic event that establishes a
    species by the technical definition of reproductive isolation.  To
    be sure, the later success of this species in competition may
    depend upon its subsequent acquistion of adaptations; but the
    origin itself may be non-adaptive.  We can, in fact, reverse the
    conventional view and argue that speciation, by forming new
    entities stochastically, provides raw material for selection.
                                                       [page 124]

I highly recommend this paper.  It is my impression that Gould is very
popular in this newgroup but that few have read more than his popular
books and/or his essays in Natural History.

-- 
                                                                    |
Paul DuBois     {allegra,ihnp4,seismo}!uwvax!uwmacc!dubois        --+--
                                                                    |
Ritual and Ceremony:  Life Itself.                                  |

friesen@psivax.UUCP (Stanley Friesen) (08/10/85)

In article <1361@uwmacc.UUCP> dubois@uwmacc.UUCP (Risky Rat) writes:
>
>I misspoke somewhat.  What I should have said, was that natural
>selection is considered unimportant more and more in regard to
>*speciation* - not evolution in general.  
>
	Well, I would not say "more and more". There is currently
considerable controversy over this issue, and it is not at all clear
which way it is actually shifting. There is much new evidence that
coontradicts the predictions of the P.E. purists. Thus the theory
may actually be tending towards some sort of middle ground.

>Anyway, to clarify, my favorite passage comes from:
>
>    Stephen Jay Gould, "Is a new and general theory of evolution
>    emerging?", _Paleobiology_, 6(1), 1980, 119-130.
>
>    come into contact.) But in saltational, chromosomal speciation,
>    reproductive isolation comes first and cannot be considered as an
>    adaptation at all.  It is a stochastic event that establishes a
>    species by the technical definition of reproductive isolation.  To
>    be sure, the later success of this species in competition may
>    depend upon its subsequent acquistion of adaptations; but the
>    origin itself may be non-adaptive.  We can, in fact, reverse the
>                                                       [page 124]
>
	Note, that he is here only talking about one kind of
speciation, chromosomal speciation. This by no means the *only*
kind of speciation, and I do not think even Dr Gould would claim
it is the most important mode of speciation. Very few other types
of speciation have actually been well verified as even being
possible, so this leaves this as a rather special case.

>I highly recommend this paper.  It is my impression that Gould is very
>popular in this newgroup but that few have read more than his popular
>books and/or his essays in Natural History.
>
	Well, I do have a lot of respect for him, although I am far
from agreement with him on many points. Certainly his books are worth
reading, as an introduction to one school of thought among modern
biologists.
-- 

				Sarima (Stanley Friesen)

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