WHY CREATIONISM IS WRONG

THE CAMBRIAN EXPLOSION

WHEN CHARLES DARWIN LOOKED AT THE FOSSIL RECORD OF HIS DAY HE WAS TROUBLED BY THE SUDDEN APPEARANCE OF FOSSILS IN THE PERIOD KNOWN AS THE CAMBRIAN. IN ROCKS PRIOR NO VISIBLE FORMS OF LIFE WERE FOUND, YET HIS THEORY DEMANDED A LONG PERIOD OF GRADUAL DEVELOPMENT FOR LIVING THINGS AS COMPLEX AS CAMBRIAN LIFE.

Discoveries since Darwin, in the 1940s and since, have uncovered a rich fauna of animals in the latest Pre-Cambrian. The oldest animals now date to about 590 mya, and seem to be porifera [sponges] and cnidarians - radially symmetric animals, like coral polyps, anemones and jellyfish. Other Pre-Cambrian life seems to be primitive forms of bilaterally symmetric animals, to which all other animals belong.

New discoveries are being made all the time. Recently embryos of animals have been found preserved in phosphate sediments, and these seem to appear before their adult forms in the fossils ['Precambrian Animal Diversity: Putative Phosphatized Embryos from the Doushantuo Formation of China,' PNAS 97:9:4457-4462.] Most animal Phyla [except arthropods and chordates] actually have a two-step developmental process which initially produces a simple larval form that then DOESN'T grow into the adult form like direct-developing larva, but instead produces the adult from a cluster of 'set-aside' cells. Thus most phyla could have existed and diversified in microscopic form prior to the Cambrian. A global change in environmental conditions might then have allowed evolution of larger adult forms, achieved through the two-step developmental process.

The Pre-Cambrian is also the time when the first animal trails appear and recent work suggests that they are due to simple animal forms like anemones and flat-worms. So the Pre-Cambrian is the beginning of animal life and not some 'blank' in the fossils.

However the Cambrian itself also poses puzzles. Early Cambrian deposits were discovered in the early 1900s that exquisitely preserved soft-bodied animals, for example the Burgess Shale. When these Cambrian strata were re-examined in the 1970s and 80s many believed that the animals found corresponded to totally new Phyla, since they fit none of the existing Phyletic categories. Such new Phyla seemingly came out of nowhere.

Was this a wholly new Creation process other than evolution showing up in the fossils? Perhaps not. Our Phyla categories are human inventions that define membership based on sets of characteristics. Such a system does not accommodate the kind of mosaic evolution known so well from other evolutionary lineages. An animal might have several characters from one Phylum and several from another, so it would fit in neither and be classed as its own group. Hence the illusion of 'fully-evolved' Phyla that are in reality forms intermediate between categories.

Cladistic Analysis is a powerful technique for determining relationships between living things that analyses them on a character by character basis, rather than as sets of characters. When Cladistic Analysis was applied to the 'new' Phyla, many disappeared and became allied to one established group or another, thus showing their true colours as Intermediate forms.

This doesn't mean the Cambrian is totally understood. Many theories exist as to why animals appeared in the period 590 - 520 mya and none are as yet fully supported by the evidence, but is the Cambrian a phenomenon unexplainable by evolution? Probably not.

Glenn Morton, ex-Creationist, has a new page on the Cambrian Explosion, with nicer pictures and more links than mine :o) CAMBRIAN EXPLOSION?

Glenn Morton has a new page on errors commonly made by Creationists 12 ERRORS

GENESIS IS HISTORY? GENESIS

TRANSITIONAL FORMS - WHERE ARE THEY? TRANSITIONS

HOW CAN A RANDOM PROCESS CREATE COMPLEXITY? RANDOM

LIFE'S ORIGIN: THE ULTIMATE MYSTERY OF BIOLOGY. ABIOGENESIS

GLENN MORTON

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WHAT IS EVOLUTION?

Who Is God?

INDEX


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