Copyright 1998 Glenn R. Morton, This may be freely distributed so long as not changes are made to the text and no charge is made. (home.entouch.net/dmd/celltype.htm)
I have just read a fascinating article 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” Paleobiology 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.
Now, can the global flood paradigm explain this order in the fossil record? No! Assuming the onset of the flood was at the base of the Cambrian, it is clear that throughout the Cambrian period complexity in cell type increased. Yet the usual explanations for why animals appear as they do, mobility and ecological zonation, simply won't work here. Porifera, Cnidaria, Haemocoelic Bilaterian, Arthropoda, Echinodermata, and annelids are not significantly different in mobility. Thus the flood can not explain why complexity increases as we go up the geological column, but evolution can explain it.
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