Honorable Forum:
This kind of post is the sort of thing that makes me prefer listservs
like this one over more formal expressions in cloistered publications.
This is not to say that the former do not remain necessary during the
transition to some kind of meta-analytical transition, only that, like
the haystack that is Nature, this pixel version of the quill and
vellum is where intellectual mutations might be found; at least it
demonstrably can be a much more vigorous and vibrant grinding-stone
for the cutting edge. Admittedly, much of that potential remains to be
realized, and many a random intellectual allele fades, perhaps never
to arise again for generations. But there are signs of listserv drift
toward adaptations reflective of the cyberenvironment that can
accelerate intellectual development if not transformation. In addition
to information, this list consequently gives me pleasure.
That said, I thank Cruzan for his brief but direct and comprehensive
responsive response to my question.
"So evolution is not necessarily directional and is not goal
oriented, it is just any genetic change due to selection, drift, gene
flow between populations, or mutation. Even natural selection as a
force for adaptation to the current environment only means an increase
in fitness as long as the environment remains the same." --Cruzen
I admittedly have spent far too much time out in the sun, but my
observations from the other end of the microscope have led me to
wonder, as it appears that the "current environment" can both be
considered tightly controlled, such as in the lab, and on a perhaps
arbitrary time-scale or a rather much longer envelope within which
fluctuations can be seen as limited, that change, both represented by
that rather limited range of fluctuations (at least free of major
asteroid impacts, etc.), is the name of the game. If that is true, is
there a need to qualify so natural selection? And how can evolution be
directional at all?
WT
----- Original Message -----
From: "Mitch Cruzan" <[email protected] <mailto:[email protected]>>
To: <[email protected] <mailto:[email protected]>>
Sent: Saturday, May 15, 2010 8:04 PM
Subject: Re: [ECOLOG-L] EVOLUTION Advancement? Re: [ECOLOG-L] facts,
laws, and theories
> Sorry about the confusion. I think we were flipping back and forth
> between public perceptions and science. So, from a science perspective:
> Evolution means change through time - change in any way, including
> 'change in allele frequencies within populations between generations,'
> 'decent with modification,' or genetic adaptation to the environment.
> Darwin considered natural selection as the primary force for change -
> for improved fitness within one environment. But environments can
> fluctuate more rapidly than populations can sometimes evolve, so they
> are constantly chasing a moving target. Through the 1960's biologists
> were focused on natural selection as the primary or only force of
> evolution.
> Wright emphasized genetic drift - random genetic changes - as an
> important evolutionary force in the 1930's, but its effects were
> considered minor and unimportant until Kimura proposed his neutral
> theory of evolution. As information on molecular genetics accumulated
> it became increasingly obvious that genetic drift was as prevalent an
> evolutionary force as natural selection.
> So evolution is not necessarily directional and is not goal oriented,
> it is just any genetic change due to selection, drift, gene flow
between
> populations, or mutation. Even natural selection as a force for
> adaptation to the current environment only means an increase in fitness
> as long as the environment remains the same.
>
> Hope that helps.
>
> Mitch
>
> Wayne Tyson wrote:
>> I, too, am naive. So evolution is about "advancement--toward
something better" but is not "goal-oriented." "Better-adapted" I can
understand, but "towards" seems to imply a goal. "Improvement?" Could
Cruzan (or anyone else) clarify, please?
>>
>> WT
>>
>>
>> ----- Original Message -----
>> From: "Mitch Cruzan" <[email protected] <mailto:[email protected]>>
>> To: <[email protected] <mailto:[email protected]>>
>> Sent: Friday, May 14, 2010 8:50 PM
>> Subject: Re: [ECOLOG-L] facts, laws, and theories
>>
>>
>>
>>> Your question reminds me of the difference between science
education
>>> as it should be vs. science education as it is. There are
equations as
>>> simple and elegant as those describing the effect of gravity on an
>>> object that describe processes of evolution. The trajectory of a
allele
>>> frequency in response to selection can be described with
predictability
>>> and simplicity of the same order as those equations in basic
physics -
>>> pick up any introductory textbook on population genetics and you will
>>> find the answers there.
>>>
>>> The key thing is that Mendelian inheritance provides us with a
>>> logical and predictable framework to start from. Adding the
effects of
>>> say, selection, to departures from the Hardy-Weinberg expectation
then
>>> comes down to simple algebra that most any high-school or beginning
>>> college student could understand. Does it gloss over complications?
>>> Yes, of course it does, just as the the simple equations of
acceleration
>>> under gravity ignore effects of the atmosphere, drag ratios, and many
>>> other things. So the response to selection can be dampened by lower
>>> heritability just as the acceleration of the object can be slowed
by the
>>> atmosphere. The mathematical foundation of evolution is just as
simple
>>> and complex as that of physics.
>>>
>>> I do not blame you for being naive about the existence of this
body
>>> of theory, but blame our science education system that has been
crippled
>>> by zealots who scream at any inclusion of evolution in biology -
>>> including the simple effects of selection on allele frequencies in
>>> populations (not to mention migration, genetic drift, and mutation).
>>>
>>> Can we boil down the 'Law of Evolution' to a simplistic form that
>>> everybody can understand? Sure! The 'Law of Gravity' is about
things
>>> falling - everything falls, right? The law of evolution, at its
core,
>>> is about change - change is inevitable, or as Bill Clinton was
fond of
>>> saying, "change is good." Evolution has permeated our culture to be
>>> associated with change -advancement - towards something better
>>> (evolution is not goal oriented). This is just as inaccurate as the
>>> common understanding of the 'law of gravity' (everything falls
down).
>>> So everything about the Law of Evolution is just as simple,
predictable,
>>> complex, and inaccurate in colloquial understanding as of the Law of
>>> Gravity.
>>>
>>> Glad we had this little chat.
>>>
>>> Mitch
>>>
>>> [email protected] <mailto:[email protected]> wrote:
>>>
>>>> Mitch Cruzan wrote:
>>>>
>>>> >Perhaps it would be more clear to people if we referred to
>>>>
>>>>
>>>>> the 'law of evolution' rather than using the ambiguous word
'theory.'
>>>>>
>>>>>
>>>> "Laws" in the physical sciences state simple, repeatable
observations. In general, such a "law" may be summarized in a
mathematical statement and the statement may be used to calculate the
value of one or more variables when others are known. Though most
laypersons misunderstand it, the acceleration under gravity equation
that high school or freshman college physics students learn is an
example and represents the law of gravity. The theory of gravity, on
the other hand, is considerably more complex, and as I understand it,
it is a part of the "Grand Unified Theory" that physicists seek.
>>>>
>>>> How can evolution be so summarized? Can we make a prediction
about a future evolutionary outcome? Can we craft an equation that
models it in the simple way that the law of gravity can be modeled by
an equation? Though evolution is factual, an appropriate analogy to
physical laws that applies in the case of the theory of evolution is
something like the Hardy-Weinberg principle, which states a simple
relationship that can be repeatedly demonstrated, and can be used to
accurately predict future allele frequency in a population. It does
not constitute the entirety of evolutionary theory, and no single
physical law constitutes the entirety of a given physical theory.
>>>>
>>>> At least that's how I understand the relationship of what are
called "laws" to theory. I used to tell my students that a "fact" was
something that was repeatedly observable, and that was generally
understood to be true. I then stated that theories explain facts.
Regarding evolution in this sense: Chimpanzees and other great apes
share a considerable amount of morphological and genetic similarity
with people. That is a fact. The theory of evolution explains those
facts by invoking phylogeny.
>>>>
>>>> I would state further to my students that the theory of evolution
(the explanatory model, still under development) explains the facts of
evolution (observed natural selection of antibiotic existence by
microbes, and observed interbreeding of domestic dogs and wolves for
example).
>>>>
>>>> Now, if we want to substitute the word fact for theory in
describing the concept of evolution to laypersons, then we'd be
correct. Evolution is a repeatedly observed phenomenon, and the
concept is generally understood to be true. I suppose what is known
as a law in science is a fact, also, in that sense, but we can't
summarize evolution with a single, simple model like we can a physical
law. At least I can't.
>>>>
>>>> I hope this helps rather than hinders the discussion.
>>>>
>>>> David McNeely
>>>>
>>>>
>>>>
>>
>>
>>
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