From the Mailbag

I got a message in email asking for my opinion on a couple of quotations. (Reposted here by permission.)

From: “D.R. Smith”
Subject: Alleged problems with evolution…
Date: Thu, 01 Jun 2006 08:02:33 -0500

Mr. Elsberry:

Your name/email information appeared at the “Evolutionary Zoologists” website, which came up when I was trying to dig up some information on the two gentlemen mentioned below.

In the ongoing (and never ending, it seems) debate between the so-called “evolutionists” and “creationists”, I made the comment to an evolution skeptic that only ONE relatively radical change between organisms was necessary to suggest that speciation (relatively radical change) was a plausible possibility for every other organism as well. He agreed, and asked what is the best documented (through the fossil record) example of that. I responded that whales evolving from land mammals appears to be the best documented example of evolutionary morphology.

He responded with these two quotes that dispute the contention that the fossil record is being interpreted accurately:

The lack of transitional forms in the fossil record [is] realized by evolutionary whale experts like the late E.J. Slijper: “We do not possess a single fossil of the transitional forms between the aforementioned land animals [i.e., carnivores and ungulates] and the whales.” (E.J. Slijper, Dolphins and Whales (Ann Arbor, MI: University of Michigan Press, 1962), p. 17.)

Both modern branches of whales, the toothed whales (Odontoceti) and baleen whales (Mysticeti), appear abruptly in the fossil record. Stahl points out the following regarding the skull structure in both types: “shows a strange modification not present, even in a rudimentary way, in Basilosaurus and its relatives: in conjunction with the backward migration of the nostrils on the dorsal surface of the head, the nasal bones have been reduced and carried upwards and the premaxillary and maxillary elements have expanded to the rear to cover the original braincase roof.” (B.J. Stahl, Vertebrate History: Problems in Evolution (New York: McGraw-Hill, 1974), p. 489)

Slijper appears to have the credentials that grant him at least some degree of authority/credibility so that categorically dismissing his comments without considerable research may be premature (although he’s quoted @ answersingenesis, a clearly anti-evolution site). And Stahl’s comment appears to be specific enough so that the link between land mammals and whales (as established through the similarity in jawbones) is not as much of a slam-dunk (agreed upon by the vast majority of researchers) as it is often presented.

My own acceptance of evolution as the elegant explanation that it is is based on its consistency with a wide variety of sciences, all of which cross-verify the amount of time needed for evolution and even abiogenesis, as well as providing a mechanism for change simple enough to not require intelligent design. I take the land-animal-to-whale transition as a matter of faith/probability — and talkorigins.org represents that transition as perhaps the best documented transitional fossil record that we have.

But I don’t have an effective way to rebut the above comments. They’re probably out of context — typical creationist misquote — but I can’t prove that yet.

Are you familiar with these gentlemen — and do you know a specific-enough argument that neutralizes these contentions?

Thanks for your time.

Respectfully,

Doug Smith

Slijper and Stahl are authoritative enough, but one has to keep in mind that the state of the evidence changes over time. In 1962 and 1974, those statements were reasonable. Today, however, they are not. Fossil whales at various stages have now been found. Gingerich and Thewissen began looking in the right places (Egypt and Pakistan, as it turned out), and have each contributed to a nice set of fossils documenting the divergence of whales from terrestrial precursors. This research program is pretty much a post 1990 thing.

So today someone who dismissed a fossil record for whales would simply be revealing their ignorance.

One of the cool bits of research on fossil whales is that the fossils were subjected to analysis for varying isotope distributions, and the transition from fresh-water to marine environments is not only documented, but has an estimate of having occurred over a period of about 4 million years.

See also:
http://www.talkorigins.org/features/whales/
http://www.talkorigins.org/indexcc/CC/CC216_1.html
http://www.talkorigins.org/faqs/comdesc/section2.html

Wesley

Wesley R. Elsberry

Falconer. Interdisciplinary researcher: biology and computer science. Data scientist in real estate and econometrics. Blogger. Speaker. Photographer. Husband. Christian. Activist.

4 thoughts on “From the Mailbag

  • 2006/06/04 at 5:34 pm
    Permalink

    I made the comment to an evolution skeptic that only ONE relatively radical change between organisms was necessary to suggest that speciation (relatively radical change) was a plausible possibility for every other organism as well.

    Talk about a misunderstanding of what speciation is.

  • 2006/06/05 at 2:40 am
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    Well, yes. Speciation doesn’t require “relatively radical change” unless one argues that any isolating mechanism is the same thing as a “relatively radical change”. I like the example of the pseudoscorpions published by the Zehs in the 1990s, where there was apparently cryptic speciation — the morphology of two reproductively isolated populations stayed the same, but (IIRC) there was almost complete post-zygotic mortality in crosses between those populations.

  • 2006/06/05 at 2:46 am
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    OK, found my previous post on this made back in 1993 on the Fidonet Evolution Echo:

    Zeh, D.W. & J.A. Zeh. 1994. When morphology misleads: interpopulation uniformity in sexual selection masks genetic divergence in harlequin beetle-riding pseudoscorpion populations. Evolution 48(4):1168-1182.
    “How can such interpopulation homogeneity in male sexually dimorphic traits exist in the face of strong genetic divergence? We propose that sexual selection, oscillating between favoring small and then large males, maintains such high levels of male variability within each population that it has obscured a speciation event in which genetic divergence and postzygotic incompatibility have clearly outpaced the evolution of prezygotic reproduction isolation.”
    The species name of the subjects is Cordylochernes scorpiodes. Zeh and Zeh have established that the French Guiana and Panama populations are actually sibling species, despite current taxonomic classification as a single species. The nifty thing is that this study actually applied tests of reproductive isolation. Heteropopulation zygotes invariably aborted early in development. Zeh and Zeh noted little difference at the behavioral level.
    “The research has established that geographically distant
    populations may diverge genetically, become postzygotically isolated, and yet show little evidence of this reproductive divergence at the phenotypic level.” It would seem that confidence that lack of morphological divergence necessarily indicated lack of genetic divergence is misplaced.

  • 2006/06/07 at 11:19 am
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    A red flag goes up when I see someone quoting Learned Biologists c. 1962. Fast-forward thirty years, to a mere 14 years ago, and scientists were in the midst of discovering a lovely series of ungulate-to-whale transitional fossils. Quotations from back when computers were steam-powered should be greeted with a very raised eyebrow and a polite request for a survey of the recent research.

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