I have stayed out of your discussion of top-down phyletic change until I could
get your article and read it. I have run an experiment which illustrates what
I feel is a very bad, statistical problem with your top-down viewpoint.
You wrote:
>8. Finally, I hypothesize that the process of development is the process
> underlying the early stages of the top-down direction of phyletic change.
> Principles of development, in this view, apply to large groups of animals
>over geologic time as well as to individual organisms over one life span.
> Just as the somatic genome of the individual organism is the primary source
>of individual development, so the germ-line of the lineage is the primary
>source of phyletic development. Later as development processes run out of
>steam, Darwinian mechanisms, especially natural selection, come into play.
> This switch-over is suggested by the accelerating number of species
>generated in the latter half of the Phanerozoic, especially in the Cenozoic,
>but with no new major higher taxonomic categories forthcoming. Since species
>are the by-product of natural selection it may be inferred that the Darwinian
>natural selection is at work. Its function is to add minor variations to
>species to insure, as van Inwagen suggests, "that species possess sufficient
>diachronic flexibility that they aren't just automatically wiped out by the
>first environmental change that comes along" and thus they enhance the
>survival of the lineage. (Darwinism: Science or Philosophy, Buell and
>Hearn, 1994).
>
The top down appearance of your charts is due to the fact that you are
counting first occurrences of phyla, classes, orders, families, genera, and
species.
I generated the following sequence by a random process The alternating letters
and numbers represent subsequent hierarchical levels. Each level was chosen
from 5 possibilities. For instance the sequence
C2G8O can be read as
Phylum C
Class 2
Order G
Family 8
Genus O
Here is the sequence I ran (sorry about the ":" character)
sequence; appearance order
C2G8O 1
I0G6O 2
A4G6O 3
F2G6M 4
I3G7P 5
K0I7O 6
J3K7L 7
D0J8M 8
C3H9L 9
B3G6O 10
E0H5N 11
I0J7L 12
E4K:O 13
F3I9O 14
G0J9L 15
C4G:N 16
G5J7L 17
C1G9P 18
C0H6P 19
I3J:O 20
E1I:K 21
C2H9L 22
G0H9N 23
F4H9P 24
E2J6N 25
D4I8L 26
E4I7L 27
H0J7M 28
F5H7P 29
C1I8L 30
J5I9L 31
G0J:M 32
G3G9N 33
I3K9M 34
F2H7K 35
E5F9P 36
C4I9N 37
D4J:O 38
F1J9N 39
C2J6M 40
C4F8L 41
F2I9L 42
H3G:M 43
C1I9N 44
J5G7K 45
H1J5P 46
B3H6L 47
B1K6N 48
B2G9O 49
H2J9O 50
*********
What this breaks down to is the first appearance of each taxon is as follows.
Appearance of taxon (step):
C C2 C2G C2G8 C2G8O
1 1 1 1 1
C3 C3H C3H9 C3H9L
9 9 9 9
C4 C4G C4G: C4G:N
16 16 16 16
C1 C1G C1G9 C1G9P
18 18 18 18
C0 C0H C0H6 C0H6P
19 19 19 19
C2H C2H9 C2H9L
22 22 22
C1I C1I8 C1I8L
30 30 30
C4I C4I9 C4I9N
37 37 37
C2J C2J6 C2J6M
40 40 40
C4F C4F8 C4F8L
41 41 41
C1I9 C1I9N
44 44
What are the average appearances of this phylum?
C appears in step 1
the average order appears in step 12,6
The average class appears in step 23.3
The average family appears in step 25.1
********
This precisely matches the data you cite for top-down progression of
evolution. It would appear to me that your concept is based upon a
statistical necessity when you count only the first appearance of a
hierarchical system.
glenn
Foundation,Fall and Flood
http://members.gnn.com/GRMorton/dmd.htm