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Archive for the ‘Fossil Record’ Category

My recent comment to RJS at Jesus Creed on the fossil record (with revisions):

It seems to me that what you often do is “fossil-mining” which is analogous to “quote-mining.”  You bring up individual fossils that you think are “transitional” but you take them out of context in a way that is somewhat misleading.  The context is the overall pattern in the fossil record, which is sudden appearance of species and stasis over time.  The fossil you mention does not change that pattern at all.  Moreover, the fossil may or may not be a “transitional” fossil.  We would need to know more to know if it was part of a step by step pattern showing gradual change from one animal to a significantly different kind of animal.  We generally don’t have those kinds of transitions in the fossil record, so there is reason to be skeptical that this particular fossil was part of that kind of progression.

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Here is an extended quote from Stephen Jay Gould’s “The Episodic Nature of Evolutionary Change,” pp. 181-182, in which he explains the problems with the fossil record, and how he believes his pet theory of “punctuated equilibrium” purportedly solves this “uncomfortable paradox.”  Of course, you can take these facts regarding the fossil record and draw quite different inferences.

The extreme rarity of transitional forms in the fossil record persists as the trade secret of paleontology. The evolutionary trees that adorn our textbooks have data only at the tips and nodes of their branches; the rest is inference, however reasonable, not the evidence of fossils. Yet Darwin was so wedded to gradualism that he wagered his entire theory on a denial of this literal record:

The geological record is extremely imperfect and this fact will to a large extent explain why we do not find interminable varieties, connecting together all the extinct and existing forms of life by the finest graduated steps. He who rejects these views on the nature of the geological record, will rightly reject my whole theory.

Darwin’s argument still persists as the favored escape of most paleontologists from the embarrassment of a record that seems to show so little of evolution directly. In exposing its cultural and methodological roots, I wish in no way to impugn the potential validity of gradualism (for all general views have similar roots). I only wish to point out that it is never “seen” in the rocks.

Paleontologists have paid an exorbitant price for Darwin’s argument. We fancy ourselves as the only true students of life’s history, yet to preserve our favored account of evolution by natural selection we view our data as so bad that we never see the very process we profess to study.

For several years, Niles Eldredge of the American Museum of Natural History and I have been advocating a resolution to this uncomfortable paradox. We believe that Huxley was right in his warning. The modern theory of evolution does not require gradual change. In fact, the operation of Darwinian processes should yield exactly what we see in the fossil record. It is gradualism we should reject, not Darwinism.

The history of most fossil species includes two features particularly inconsistent with gradualism:

1. Stasis. Most species exhibit no directional change during their tenure on earth. They appear in the fossil record looking much the same as when they disappear; morphological change is usually limited and directionless.
2. Sudden appearance. In any local area, a species does not arise gradually by the steady transformation of its ancestors; it appears all at once and “fully formed.”

This summary of the fossil record has been the accepted view of paleontologists for more than 20 years now, as confirmed by Donald Prothero in 2009. See here.

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Comments aren’t working for me at Biologos, so I am posting mine here:

This post is another highly selective treatment of the evidence.  It seems that the writer is not asking the question, “Is Darwinian evolution the best explanation for the Cambrian explosion?”  He rather seems to be asking:  “Can we shoehorn the Cambrian fossils into our favored theory?”

Arguing that the Ediacara fossils are on a continuum with the Cambrian fossils is highly controversial and is not mainstream.  See here.

As for the Gould quotes, Darrel says they are too old, but doesn’t explain what has changed to make them obsolete.  This post contains a summary and link to Donald Prothero from 2009:

“Thus, over 35 years after the original 1972 paper, we have a different kind of “two cultures” phenomenon of people with different mindsets talking past one another. Paleontologists have agreed for decades now that the prevailing message of the fossil record is stasis despite big changes in the environment.”

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I was planning a longer post on this topic at some point.  But when I saw the Evo News blog pick up on it, I had to jump in for a brief comment.  The problem with the Biologos page on “What Does the Fossil Record Show?” is more serious than that post indicates.  It is not just selective; it is factually wrong and very misleading:

Organisms have changed significantly over time.  In rocks more than 1 billion years old, only fossils of  single-celled organisms were found. Moving to rocks that are about 550 million years old, fossils of simple, multicellular animals can be found.  At 500 million years ago, ancient fish without jawbones surface; and at 400 million years ago, fish with jaws are found.  Gradually, new animals appear: amphibians at 350 million years ago, reptiles at 300 million years ago, mammals at 230 million years ago and birds at 150 million years ago.

When they say, “Moving to rocks that are about 550 million years old, fossils of simple, multicellular animals can be found,” they must be talking about the Cambrian animals.  (If they are not talking about the Cambrian animals, then this omission would be even more deceptive.)  But the Cambrian animals are not “simple” at all.  They are highly complex.  Trilobite eyes are astoundingly complex.

“Gradually, new animals appear . . .”  This is simply false.  As Donald Prothero explained in 2009, paleontologists agree that the overall pattern in the fossil record is one of sudden appearance and stasis, not “gradualism”:

Once “punctuated equilibrium” became a hot topic, it dominated the journals and scientific debates. I vividly remember sessions at each professional meeting during the 1970s as knock-down drag-out fights between the old-guard gradualists and the “Young Turks” led by Gould, Eldredge, and Steve Stanley. Gould and Eldredge (1977) effectively answered most of the early criticisms of the “punctuated equilibria.” By the mid-1980s, a consensus had emerged within the paleontological community that nearly all metazoans (vertebrate and invertebrate, marine and terrestrial) show stasis and punctuated speciation through millions of years of geologic time and strata, with only minor possible examples of gradual anagenetic change in size (Geary 2009; Princehouse 2009; Hallam 2009; Jablonski 2000, 2008). That has been the accepted view of paleontologists for more than 20 years now.

Yet one would never know this by looking at the popular accounts of the debate written by non-paleontologists, who still think it is a controversial and unsettled question. Even more surprising is the lack of response, or complete misinterpretation of its implications, by evolutionary biologists.

Who wrote the Biologos summary?  Darrel Falk, a biologist.

Why is Biologos so interested in dumbing down the church as to the scientific consensus in this important area?  Do they believe that Christians can’t handle the truth?

Biologos seems to prefer the “step way way back, blur the details” version of the fossil record.  Thank goodness we have top paleontologists like Stephen Jay Gould to give us a more accurate account:

Step way way back, blur the details, and you may want to read this sequence as a tale of predictable progress: prokaryotes first, then eukaryotes, then multicellular life. But scrutinize the particulars and the comforting story collapses. Why did life remain at stage 1 for two-thirds of its history if complexity offers such benefits? Why did the origin of multicellular life proceed as a short pulse through three radically different faunas, rather than as a slow and continuous rise of complexity?

This quote barely scratches the surface of the problems posed by the fossil record, including the Cambrian Explosion and the Ediacaran Explosion.

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