On Thu, 26 Feb 1998 15:40:27 -0500, Bill Hamilton wrote:
BH>It's dangerous to use dictionary definitions, but this comes from Webster's
>Ninth New Collegiate Dictionary, which has impressed me with its
>definitions in the mathematics and engineering fields. Besides, it makes
>my point :-).
>
>Macroevolution n (1939): evolution that culminates in relatively large and
>complex changes, (as in species formation)
>
>Speciation brings about a new population that is reproductively isolated
>from the parent population. That ensures that the different
>characteristics of the new population will survive -- at least for a time.
>The changes may be very small, but they persist. So it would seem that
>speciation -- which I believe many young-earth creationists now accept --
>is the fundamental process needed for macroevolution to occur.
There is confusion in evoltionary theory on what "macroeveolution" is.
Gould defines it variously as:
1. "large-scale evolution":
"The strict version, with its emphasis on copious, minute, random
variation molded with excruciating but persistent slowness by natural
selection, also implied that all events of large-scale evolution
(macroevolution) were the gradual, accumulated product of
innumerable steps, each a minute adaptation to changing conditions
within a local population. This "extrapolationist" theory denied any
independence to macroevolution and interpreted all large-scale
evolutionary events (origin of basic designs, long-term trends,
patterns of extinction and faunal turnover) as slowly accumulated
microevolution (the study of small-scale changes within species)."
(Gould S.J., "Hen's Teeth and Horse's Toes", 1984, p13)
2. "major structural transition":
"Orthodox neo-Darwinians extrapolate these even and continuous
changes to the most profound structural transitions in the history of
life: by a long series of insensibly graded intermediate steps, birds are
linked to reptiles, fish with jaws to their jawless ancestors.
Macroevolution (major structural transition) is nothing more than
microevolution (flies in bottles) extended. If black moths can displace
white moths in a century, then reptiles can become birds in a few
million years by the smooth and sequential summation of countless
changes. The shift of gene frequencies in local populations is an
adequate model for all evolutionary processes - or so the current
orthodoxy states." (Gould S.J., "The Return of the Hopeful
Monster", in "The Panda's Thumb", 1980, p156)
Mayr, however, defines macroevolution the way you propose, as
"transpecific evolution" (which has the effect of denying its
reality):
"The proponents of the synthetic theory maintain that all evolution is due
to the accumulation of small genetic changes, guided by natural
selection, and that transpecific evolution is nothing but an
extrapolation and magnification of the events that take place within
populations and species. A well-informed minority, however,
including such outstanding authorities as the geneticist GoldSchmidt,
the paleontologist Schindewolf, and the zoologists Jeannel, Cuenot,
and Cannon, maintained until the 1950's that neither evolution within
species nor geographic speciation could explain the phenomena of
"macroevolution," or, as it is better called, transpecific evolution.
These authors contended that the origin of new "types" and of new
organs could not be explained by the known facts of genetics and
systematics." (Mayr E., "Populations, Species and Evolution", 1974, p351)
Eldredge notes that what he calls "ultra-Darwinians" (which are really
just consistent Neo-Darwinists like Mayr, Maynard Smith, Williams, etc)
don't even like the word "macroevolution" because it implies that
natural selection was not up to the job:
"The very term macroevolution is enough to make an ultra-Darwinian
snarl. Macroevolution is counterpoised with microevolution-
generation by generation selection-mediated change in gene
frequencies within populations. The debate is over the question, Are
conventional Darwinian microevolutionary processes sufficient to
explain the entire history of life? To ultra-Darwinians, the very term
macroevolution suggests that the answer automatically no. To them,
macroevolution implies the action of processes-even genetic
processes-that are as yet unknown must be imagined to yield a
satisfactory explanation of the history of life." (Eldredge N.,
"Reinventing Darwin: The Great Evolutionary Debate", 1996, pp126-
127)
But if you want to define "macroevolution" that way, ie. change above
the species level, and microevolution as change withing the species,
that's OK. But then microevolution as thus defined is not even
evolution-nothing (by definition) permanently changes, it just
fluctuates:
"The "evolution in action" of J. Huxley end other biologists is
simply the observation of demographic facts, local fluctuations of
genotypes, geographical distributions. Often the species concerned
have remained practically unchanged for hundreds of centuries!
Fluctuation as a result of circumstances, with prior modification of
the genome, does not imply evolution, and we have tangible proof of
this in many panchronic species [i.e. living fossils that remain
unchanged for millions of years]..." (Grasse P.-P., "Evolution of
Living Organisms", 1977, p130, in Johnson P.E., "Darwin on Trial",
1993, p27)
Also, the term "macroevolution" becomes so vague it is virtually
meaningless. The same term would apply to the process which made two
populations of otherwise identical fruit flies unable to cross-breed,
and the origin of fruit flies in the first place. Yet despite
billions of individual fruit flies, and thousands of species of fruit
flies and many laboratory experiments to produce mutations in fruit
flies, they have remained, from first to last, fruit flies:
"The genic differences noted between separate populations of the
same species that are so often presented as evidence of ongoing
evolution are, above all, a case of the adjustment of a population to
its habitat and of the effects of genetic drift. The fruitfly (drosophila
melanogaster), the favorite pet insect of the geneticists, whose
geographical, biotropical, urban, and rural genotypes are now known
inside out, seems not to have changed since the remotest times."
(Grasse, 1977, p130, in Johnson P.E., "Darwinism's Rules of
Reasoning", in Buell J. & Hearn V., eds., "Darwinism: Science or
Philosophy?", 1994, pp6-7)
Finally, if macroevolution is deFined as "fruit flies extended" (to
use Gould's term), then Simpson's term "quantum evolution"
would presumably have to be resurrected:
"Nevertheless there is a difference and many of the major changes
cannot be considered as simply caused by longer continuation of the
more usual sorts of minor changes. For one thing, there is excellent
evidence that evolution involving major changes often occurs with
unusual rapidity, although, as we have seen, there is no good
evidence that it ever occurs instantaneously. The rate of evolution of
the insectivore forelimb into the bat wing, to give just one striking
example, must have been many times more rapid than any evolution
of the bat wing after it had arisen. The whole record attests that the
origin of a distinctly new adaptive type normally occurs at a much
higher rate than subsequent progressive adaptation and diversification
within that type. The rapidity of such shifts from one adaptive level or
equilibrium to another has suggested the name 'quantum evolution,"
under which I have elsewhere discussed this phenomenon at greater
length" (Simpson G.G., "The Meaning of Evolution", 1949, p235)
Eldredge adds that Simpson also called this "megaevolution":
"But macroevolution need not carry such heavy conceptual baggage.
In its most basic usage, it simply means evolution on a large-scale. In
particular, to some biologists, it suggests the origin of major groups-
such as the origin and radiation of mammals, or the derivation of
whales and bats from terrestrial mammalian ancestors. Such sorts of
events may or may not demand additional theory for their
explanation. Traditional Darwinian explanation, of course, insists not.
But George Simpson, as I have already noted, felt that the abrupt
Eocene appearances of both bats and whales indicate a special period
of rapid evolutionary change that demands detailed theoretical
explanation. Indeed, Simpson, noting that microevolution refers to
within-species processes, while macroevolution refers to relay lower-
ranked higher taxa (meaning genera and perhaps families), decided
that still a third term would be useful: megaevolution. This term
would embrace the very sorts of examples of large-scale evolution he
had in mind with his concept of quantum evolution." (Eldredge N.,
"Reinventing Darwin", 1996, p127)
Of course, much of what Gould and Eldredge call macroevolution, and
what Simpson called quantum- or mega- evolution, especially the origin
of new designs, I would call creation!
Steve
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3 Hawker Avenue / Oz \ Steve.Jones@health.wa.gov.au
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Perth, West Australia v "Test everything." (1Thess 5:21)
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