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] 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
