Thursday, April 7, 2016

James Shapiro & Why Evolutionary Theory Is Getting Unrecognizable

Recently I got to see a debate between Michael Ruse and Cornelius Hunter.  For the most part, Hunter argued that the facts of biology, mostly citing recent research, discredit an evolutionary explanation based on Darwin's original theory, esp. any theory dependent on common descent or positive selection.  For the most part, Ruse discussed what was historically so convincing to Charles Darwin.  This latter scheme, though it did not in any way rebut Hunter's points, seems to fit the mainstream approach. 

A similar pattern ensued in a debate a few years about ID with Michael Shermer and Donald Prothero on one side, and Stephen Meyer and Rick Sternberg on the other.  If memory serves, Shermer and Prothero mostly summarized the century-old argument for common descent for the audience, while Meyer and Sternberg attacked natural selection as a sufficient explanation.  (Reminder: ID in no way require common descent to be false, though it is quite at home in the anomalies in phylogenetics.)

With more recent mosaics (e.g. Tiktaalik and Pakicetus and other "missing links") in tetrapod evolution, the "overwhelming evidence" for "evolution as fact" seem to be an abductive inference based on fossil geology, comparative anatomy, and embryological similarity.  And now, as then in Darwin's day, a historical evolutionary process (whatever the mechanism) is compared to what a typically atheist/deist biologist presumes an anthropomorphized cosmic designer would or wouldn't have done.  This is the "one long argument" of Mr. Darwin and these theological arguments haunt science textbooks to this day. 

In an era of evolutionary thought where Darwin's Tree of Life is being discussed as an outdated concept and natural selection as maybe not being a central explanatory mechanism for macro evolution, it begs the question what biologists (or anybody) mean when they assert that "Evolution is a fact." "Evolution" may be the most overloaded term in all of science.  It refers to a historical "fact" and a "theory" of causation and a trivial phenomenon (microevolution) and a research program and a narrative (and a religion according to Michael Ruse).

James Shapiro, a fairly mainstream microbiologist and evolutionary biologist has written a book Evolution: A View from the 21st Century that challenges a lot of the assumptions of the mainstream Evolutionary Synthesis.  He differentiates between several key aspects of evolution.
General discussions of evolution, especially in the context of the “Intelligent Design” controversy, suffer from an unfortunate conflation in the minds of the lay public (and also of scientists) of three distinct questions:
[1] The origin of life
[2] The evidentiary basis for an evolutionary process
[3] The nature of evolutionary change
[emphasis mine]
When you think about, the 3rd item is all over the place right now.  There is no consensus on whether natural selection is a sufficient explanation for what Darwin used it to explain--the origin of all species--and that is an understatement.  The 1st item is in a similar state of disarray in terms of a coherent theory, but this is less surprising and more widely understood--and the chief reason why many theorists separate it from the Evolutionary Synthesis.  Now, the 2nd item is something that many, though not all, ID theorists either agree with or at least grant for argument's sake. Many ID theorists do dispute whether the evidentiary basis for common descent is as strong and coherent as neo-Darwinists and evolutionary materialists aver, but ID is generally not in conflict with an "evolutionary process" of some kind.
The one issue that has effectively been settled in a convincing way is the evidence for a process of evolutionary change over the past three billion years. The reason the answer to this question is so solid is that every new technological development in biological investigation—from the earliest days of paleontology through light microscopy and cytogenetics up to our current molecular sequence methodologies—has told the same story: living organisms, past and present, are related to each other, share evolutionary inventions, and have changed dramatically over the history of the Earth.* [emphasis added] 
How much an ID theorist agrees with a common "story" depends on what he means by "related to", "share", and "history."  Even a Young Earth Creationist might agree with these articles as stated, though Shapiro probably means "history" as the mainstream interpretation of the "fossil record" rather than simply as time.  But the majority of ID theorists, including Steve Meyer, Michael Behe, William Dembski, and even Jonathan Wells, seem to adopt or use the mainstream view of fossil dating. 

The central point of departure for Intelligent Design is whether there is a significant component of intelligence that is required for a complete explanation for the biological world.  But there is a real and general way in which both ID theorists and creationists see organisms as related to each other and sharing innovations in a non-Darwinian sense, an innovative relationship between living things that has unfolded in a dramatically changing diversity over Earth's history (whether a long history or short).  

And the question remains whether even the evidence for an evolutionary process, intelligent or not, is quite so strong without a prior conviction that all natural phenomenon have a strictly natural cause (where "natural" essentially means "material" or "physical").  As evolutionist par excellence Richard Lewontin said:
Our willingness to accept scientific claims that are against common sense is the key to an understanding of the real struggle between science and the supernatural. We take the side of science [defending science against "attackers"?] in spite of the patent absurdity of some of its constructs, in spite of its failure to fulfill many of its extravagant promises of health and life, in spite of the tolerance of the scientific community for unsubstantiated just-so stories, because we have a prior commitment, a commitment to materialism. It is not that the methods and institutions of science somehow compel us to accept a material explanation of the phenomenal world, but, on the contrary, that we are forced by our a priori adherence to material causes to [seek only material causes  in science]. Moreover, that materialism is absolute, for we cannot allow a Divine Foot in the door. The eminent Kant scholar Lewis Beck used to say that anyone who could believe in God could believe in anything. To appeal to an omnipotent deity is to allow that at any moment the regularities of nature may be ruptured, that miracles may happen.
And that, Charlie Brown, is the meaning of Slippery Slope. Somehow, this "Divine Foot in the door" didn't stop scientists like Isaac Newton, nor the many "creationist" scientists that preceded both Darwin and widespread Deism, from real, ground-breaking science. Somehow, in the absence of an "absolute" materialism, both common sense and the belief in a universe made comprehensible by a rational Designer made them expect an orderly world where miracle was exceptional but not excluded.

Wednesday, April 6, 2016

Non-Haeckelian Development

Some fun weirdness in the tangled “tree of life.”  Donald Williamson, a marine biologist who wondered why very different larval forms pop up willy-nilly in very different species, has a bold hypothesis.  Although his explanation is very heterodox (though it received serious support from Lynn Margulis) and is yet to be supported by any molecular data, what is much more fascinating is the extent of the problem his theory aims to solve, including the following oddities:
  1. Very similar larval forms appear in phyla with dissimilar adult body plans.
  2. Wholly different larval forms appear in the same phylum
  3. Some echinoderms are develop as protostomes, some as deuterostomes. 
  4. Some mollusks, annelids, sipunculids, and even some deuterostomes have rotifer-like trochophore larvae.
These larval variations not only challenge the Haeckelian expectations of neo-Darwinism, but they potentially put the whole protostome/ deuterostome division in question.  Here’s Williamson’s attempt to fit these larval epicycles into a Darwinistic history:

   … Brittle stars and sea urchins are very different as adults but share the unique pluteus form of larva. Why would similar larvae produce dissimilar adults [in different phyla]? Larval transfer proposes that the basic pluteus larva evolved only once, in a sea urchin, and was retained in this sea urchin’s descendants.  An ancestor of most existing brittle stars then acquired a pluteus larva by hybridizing with a sea urchin. 

    One member of this group, Kirk’s brittle star, develops directly from the fertilized egg, with no trace of a bilateral larva, and its blastopore becomes a mouth. It is, therefore, a protostome.  All echinoderm larvae are in a different developmental class, the deuterostomes, in which the mouth is a new opening; several echinoderms that have lost their larvae develop as deuterostomes. If Kirk’s brittle star lost its larva, it must have also adopted a fundamentally different pattern of cell division in the embryo. We believe, however, that Kirk’s brittle star has no larva because none of its ancestors hybridized with a sea urchin. The heart urchin Abatus cordatus and the three known species of sea daisies also have no larvae and develop as protostomes.  We suggest that this is the ancestral method of echinoderm development, and the pattern called deuterostomy came with the transferred larvae. 

  Two sea urchins, Lytechinus variegatus and Lytechinus verruculatus, are of the same genus, but the similar adults each develop from very different pluteus larvae. Such cases are difficult to explain if larvae and their corresponding adults evolved from one common ancestor.


It’s pretty curious stuff.