Re: Speciation and Macroevolution

RDehaan237 (RDehaan237@aol.com)
Wed, 17 Dec 1997 07:06:18 EST

To the list:

The controversy over the terms, micro-evolution and macro-evolution has its
origin in Darwinâs *Origin of Species*. The only diagram in the book, shows
how he imagined species were modified into higher taxonomic level (from
microevolution to macroevolution). The diagram provides the clearest picture
of the alleged evolutionary direction of modification, including the
branching pattern of speciation. (London: Dent, Everymanâs Library, 1928),
pp. 121-122.
Darwin explained his diagram as follows:

ãThus the diagram illustrates the steps by which small differences
distinguishing varieties are increased into larger differences
distinguishing species. By continuing the process for a greater number of
generations·we get eight species marked by the letters between a14 and m14
all descended from (A). *Thus, as I believe, species are multiplied and
genera are formed.*ä (p. 112. Emphasis added.)

Darwin next extended the process of modification of species-to-genera to
include higher taxonomic levels by means of natural selection, as follows:
ãI see no reason to limit the process of modification, as now explained, to
the formation of genera alone.·These two groups of *genera* will thus form two
distinct *families*, or *orders*, according to the amount of divergent
modification supposed to be represented in the diagram. And the two new
*families*, or *orders*, are descended from two *species* of the original
*genus*, and these are supposed to be descended from some still more ancient
and unknown formä (p. 115. Emphasis added.).

These clear, unambiguous statements constitute Darwinâs hypothesis of how
natural selection works. This is microevolution to macroevolution, the
bottom-up direction of evolutionary change. It may be called the Central
Dogma of Darwinism. His language, however, makes it clear that he is talking
about a hypothetical process.

Members of this list do not need to be told that studies, such as industrial
melanism in peppered moths, Darwinâs finches, change
n guppies,
and other ãevolution made visibleä studies, touted as substantiation of
macroevolution, in no way confirm macroevolution. But evolutionary authors
have lately been equating microevolution with macroevolution, blurring the
distinction between the two, claiming that formation of new species in and of
itself constitutes macroevolution.

No wonder then that studies listed below make no impression on evolutionary
authors. This research has consistently shown that the phyla have developed
in the top-down direction, from general to specific taxonomic forms, from
Phyla, to Classes, to Orders, etc. This is just the opposite direction from
what Darwin predicted.

One study of durably skeletonized marine fossils showed a hierarchy that
appeared in the top-down direction in the fossil record. Eleven distinct
Phyla were the earliest to appear, then 62 Classes, and then 307 Orders.
(Erwin, D. H., Valentine, J. W., and Sepkowski, J. J. ãA Comparative Study Of
Diversification Events: The Early Paleozoic Versus The Mesozoic.ä Evol. 41
(1987):1177-86.)

The top-down pattern of change also occurred among trilobites, an extinct
group of arthropods. The direction was from Families and Genera, reported by
Valentine. (Valentine, J. W., ãThe Geological Record,ä in Dobzhansky, Th.,
Ayala, F. J., Stebbins, G. L., and Valentine, J. W. Evolution (San Francisco:
Freeman, 1977): 335.)

The top-down pattern of change is also found in amphibia, reptiles, and
mammals; the direction being from Orders, to Families, to Genera over the
latter half of the Phanerozoic. Simpson wrote, ãEven when using the coarse
scale of periods, peaks for different categories are in the same period,
those of higher categories are earlier in the period as the data from mammals
show.ä (Simpson, G. G., . ãPeriodicity in Vertebrate Evolution.ä Jr.
Paleontol. (1952) 26:359-70. In Padian, K., and Clemens, W. A., .
ãTerrestrial Vertebrate Diversity: Episodes and Insights.ä In Valentine, J.
W., Ed. Phanerozoic Diversity Patterns: Profiles in
eton University Press, 1985), 45-46.)

Birds developed very rapidly and also follow the top-down, general-to-specific
direction of differentiation. About birds Feduccia observed, ãThis explosive
evolution paralleled that of mammals, producing all the modern lineages of
birds within about 10 million years, yielding modern *orders* by the Paleocene
and Eocene, modern *families* by the late Eocene or early Oligocene, and
modern *genera* by the Miocene (Emphasis added.). Feduccia, A., ãExplosive
Evolution in Tertiary Birds and Mammals,ä Science, 267 (1995), 638.

Rensch commented on the fossil record as follows: ãGenerally, classes are
twice as old as orders, and orders are twice as old as families, and families
are 1.5 times as old as genera. (Of course, there are many exceptions to
these generalizations.) Genera are usually about ten times as old as species,
and we have found that the average age of species is somewhere between
100,000 and a few million years.ä Rensch, B., Evolution Above the Species
Level (New York: Columbia University Press, 1960), 91-3.

I consider Darwinâs hypothesis thoroughly disconfirmed by these studies and by
the myriad of statements such as the one given by Paul Nelson.
ãMacroevolutionä came before microevolution, higher level taxa came before
specific adaptive details.

But what is just as telling is Dobzhanskyâs comments about the structure of
the organic world. He wrote,

ã. . .the two fundamental characteristics of organic diversity [are] its
discontinuity and the hierarchical ordering. Instead of all possible gene
combinations generated at random, one observes species between which . . .
intermediates are absent. . . .The genetic and structural gaps between species
of one genus are on the average smaller than between genera, smaller between
genera than between families, and so forth. . . . Let it be emphasized that
discontinuity and a hierarchical ordering are universal in the living world.ä
(Dobzhansky, Th. ãDiscontinuity of Organic Variationä In Dobzhansky, Th.
., and Valentine, J. W. Evolution (San Francisco:
Freeman, 1977) pp. 168-9.)

The top-down research cited above confirm that the natural hierarchy of the
organic world was constructed from the top-down, from general-to-specific
taxonomic forms. Evolution, i.e., natural selection and species formation
were not significant causal factors in the formation of higher taxa of
phyletic lineages. This being the case, there is no such thing as
macroevolution in the sense of Darwinâs hypothesis. It is an empty conceptual
category.

Bob