Complexity increase over time

mortongr@flash.net
Fri, 05 Nov 1999 21:00:31 +0000

I have just read a fascinating artgicle on the increasing complexity of
life in over geologic time. The article is James W. Valentine, Allen G.
Collins, and C. Porter Meyer, "Morphological Complexity Increase in
Metazoans" Paleontology 20(1994):2:131-142. The abstract states, "The
number of cell types required for the construction of a metazoan body plan
can serve as an index of morphological (or anatomical) complexity; living
metazoans range from four (placeans[sic?]) to over 200 (hominids) somatic
cell types. A plot of the times of origin of body plans against their cell
type numbers suggests that the upper bound of complexity has increased more
or less steadily from the earliest metazoans until today, at an average
rate of about one cell type per 3 m.y. (when nerve cell types are lumped)."
p. 131

They have a chart which shows the number of cell types for various classes
of animals vs. the time in which that group appears in the fossil record.
Here is a list (taken from the chart so there is a slight error as I had to
measure them):

Porifera 10 cell types 570 myr
Cnidaria 14 cell types 560 myr
Haemocoelic Bilaterian 30 cell types 560 myr
Arthropoda 51 cell types 530 myr
Echinodermata, Annelids 39 cell types 525 myr
Agnatha 64 cell types 510 myr
Cephalopoda 75 cell types 500 myr
Actinopterygii 132 cell types 400 myr
Amphibia 150 cell types 330 myr
Diapsida 154 cell types 300 myr
Aves 187 cell types 150 myr
Hominidae 210 cell types 5 myr

Clearly from this, there has been an increase in complexity throughout
geologic time. The authors then constructed a computer model with 2000
beings in which each generation of the model the beings could go up or down
in the number of cell types. This was done by pure chance. The only limit
was that they couldn't have negative cell types. over a number of
generations, the maximum number of cell types increased. When the shape of
the curve is compared with the shape of the observed increase in the fossil
record the randomly produced model matches the shape of the increase in the
number of cell types over time.

This partially explains the Cambrian explosion. Starting from a one celled
animal, the rate of increase in cell types is rapid at first but then the
rate of increase slows down. This is what the above data looks like if one
plots it. Thus, random creation of novel cellular types is consistent with
what we see in the fossil record.

Before people claim that chance is incompatible with God's creation,
remember that God is omnipotent and thus is able to control chance. Chance
doesn't control God. Nor is God a snivelling coward when He is faced with
chance.
glenn

Foundation, Fall and Flood
Adam, Apes and Anthropology
http://www.flash.net/~mortongr/dmd.htm

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