Is this illustration an accurate representation of what we see in the fossil record, the very basis of this "tree of life?" Does the study of fossils confirm or contradict evolutionary theory and the existential nature of the biological processes it proposes?
THE
In its December 4th, 1995 edition, the cover of Time Magazine called to the reader's attention a cover story reporting on "Evolution's Big Bang," saying, "New discoveries show that life as we know it began in an amazing biological frenzy that changed the planet almost overnight." The "big bang" referred to is otherwise known as a biological event called the "Cambrian Explosion."
In a period of earth's alleged history called the Cambrian period, some 570 million years ago or so, the majority of the "body plans" we see today appear to have leapt into existence in a geologic blink of an eye. So short was this period of time that if life's assumed history on this planet were condensed into a 24-hour period of time, it would be equivalent to a couple of minutes. These organisms, whose presumed ancestors appear nowhere in the fossil record, appeared suddenly, fully-formed, as complex as their apparent ancestors today.
Whereas evolutionary theory illustrates the history of life using a tree, a more accurate analogy would be that of a forest. Each tree in the great "forest of life" has at its base a single kind of creature, such as arthropods with their segmented body, jointed limbs and exoskeleton, or echinoderms, marine animals "radiating arrangement of parts and a body wall stiffened by calcareous pieces that may protrude as spines." As these early creatures with their separate and distinct body plans diversified further and further over time, more and more branches are added to each tree of life, such that we see in each group a variety of similar but different creatures: the insects, spiders and crustaceans of arthropoda, and the starfish and urchins of echinodermata.
Scientists who believe in Darwin's theory of evolution, including Darwin himself, recognize the difficulty the Cambrian explosion presents for evolutionary theory. Speaking of the Cambrian fossils, infamous atheist Richard Dawkins wrote, "It is as though they were just planted there, without any evolutionary history" (The Blind Watchmaker, New York: W. W. Norton & Co. , 1996). Of course, proponents of evolution have posited possible solutions to the problem.
Darwin, recognizing the problem of "Evolution's Big Bang", believed that the Cambrian and Precambrian periods were not yet fully represented in what we'd discovered from the fossil record. Given time, he wrote, we would discover the ancestors of these creatures earlier in the geologic strata. However, scientists have spent years and years evaluating the data, finding more and more fossils of organisms from the Cambrian and Precambrian periods. Still, the ancestors have not been found. Every time a new discovery is made, it is not a new kind of creature, but is instead a variation on the same theme: another arthropod, another echinoderm, and so forth, as fully formed and as complex as the ones found before. Again, without evidence in the record of an ancestor. Our picture of these periods of time appear to be virtually complete.
Some have argued that the ancestors to the Cambrian organisms were soft-bodied, too fragile to be preserved in the Precambrian strata. This seemed like a reasonable argument, until scientists in China discovered in the Precambrian rock tiny fossilized embryos of soft-bodied creatures! In other words, the sediment comprising the Precambrian period was able to preserve incredibly fragile, soft-bodied organisms as fossils. While the ancestors of the Cambrian creatures may have been soft-bodied, they certainly were more preservable than tiny sponge embryos.
So according to evolutionary biologists' own interpretation of the geologic record and its fossilized contents (I qualify it this way because I believe their interpretation is incorrect, a topic I will write about in the future), the majority of the kinds of organisms we have today appeared virtually overnight, fully-formed, with no apparent ancestors. No conceivable natural mechanism can account for the sudden existence of highly complex organisms--as complex, if not more so, than many we see today--representing dozens upon dozens of separate and distinct body plans. Something conceived of these disparate kinds of creatures--essence--and then assembled them in-place--existence. The philosophy of existentialism cannot account for this.
THE SEEDS OF LIFE
It's no wonder that some scientists believe these forms of life were "seeded" here by some extraterrestrial life. Called panspermia or exogenesis, exponents of this theory acknowledge the problem posed by the Cambrian explosion. They would argue, however, that this demonstrates that these early kinds of organisms were deposited on earth, as fully-formed as we find them, having originated elsewhere in the universe, and began to reproduce and diversify from there. This would seem to allow for the undirected nature of theorized evolutionary diversification, and thus its existential underpinning.
But as we'll see when we look at other recent discoveries in biology, and how they impact the theory that complex structures are formed serendipitously from parts which evolved separately, over time, the "seeds of life" theory falls flat. Stay tuned.
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