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Wednesday, June 16, 2010

The Deniable Darwin

From our friend Gauranga Kishore. Click here to read the full article

by David Berlinsky

Charles Darwin presented On the Origin of Species to a disbelieving world in 1859 - three years after Clerk Maxwell had published "On Faraday's Lines of Force," the first of his papers on the electromagnetic field. Maxwell's theory has by a process of absorption become part of quantum field theory, and so a part of the great canonical structure created by mathematical physics.

By contrast, the final triumph of Darwinian theory, although vividly imagined by biologists, remains, along with world peace and Esperanto, on the eschatological horizon of contemporary thought.

"It is just a matter of time," one biologist wrote recently, reposing his faith in a receding hereafter, "before this fruitful concept comes to be accepted by the public as wholeheartedly as it has accepted the spherical earth and the sun-centered solar system." Time, however, is what evolutionary biologists have long had, and if general acceptance has not come by now, it is hard to know when it ever will.

In its most familiar, textbook form, Darwin's theory subordinates itself to a haunting and fantastic image, one in which life on earth is represented as a tree. So graphic has this image become that some biologists have persuaded themselves they can see the flowering tree standing on a dusty plain, the mammalian twig obliterating itself by anastomosis into a reptilian branch and so backward to the amphibia and then the fish, the sturdy chordate line - our line, cosa nostra - moving by slithering stages into the still more primitive trunk of life and so downward to the single irresistible cell that from within its folded chromosomes foretold the living future.

This is nonsense, of course. That densely reticulated tree, with its lavish foliage, is an intellectual construct, one expressing the hypothesis of descent with modification.

Evolution is a process, one stretching over four billion years. It has not been observed. The past has gone to where the past inevitably goes. The future has not arrived. The present reveals only the detritus of time and chance: the fossil record, and the comparative anatomy, physiology, and biochemistry of different organisms and creatures. Like every other scientific theory, the theory of evolution lies at the end of an inferential trail.

The facts in favor of evolution are often held to be incontrovertible; prominent biologists shake their heads at the obduracy of those who would dispute them. Those facts, however, have been rather less forthcoming than evolutionary biologists might have hoped. If life progressed by an accumulation of small changes, as they say it has, the fossil record should reflect its flow, the dead stacked up in barely separated strata. But for well over 150 years, the dead have been remarkably diffident about confirming Darwin's theory. Their bones lie suspended in the sands of time-theromorphs and therapsids and things that must have gibbered and then squeaked; but there are gaps in the graveyard, places where there should be intermediate forms but where there is nothing whatsoever instead.1
Before the Cambrian era, a brief 600 million years ago, very little is inscribed in the fossil record; but then, signaled by what I imagine as a spectral puff of smoke and a deafening ta-da!, an astonishing number of novel biological structures come into creation, and they come into creation at once.

Thereafter, the major transitional sequences are incomplete. Important inferences begin auspiciously, but then trail off, the ancestral connection between Eusthenopteron and Ichthyostega, for example - the great hinge between the fish and the amphibia - turning on the interpretation of small grooves within Eusthenopteron's intercalary bones. Most species enter the evolutionary order fully formed and then depart unchanged. Where there should be evolution, there is stasis instead - the term is used by the paleontologists Stephen Jay Gould and Niles Eldredge in developing their theory of "punctuated equilibria" - with the fire alarms of change going off suddenly during a long night in which nothing happens.

The fundamental core of Darwinian doctrine, the philosopher Daniel Dennett has buoyantly affirmed, "is no longer in dispute among scientists." Such is the party line, useful on those occasions when biologists must present a single face to their public. But it was to the dead that Darwin pointed for confirmation of his theory; the fact that paleontology does not entirely support his doctrine has been a secret of long standing among paleontologists. "The known fossil record," Steven Stanley observes, "fails to document a single example of phyletic evolution accomplishing a major morphologic transition and hence offers no evidence that the gradualistic model can be valid."

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