Saturday, January 24, 2009

Darwin Bicentenary Part 3: Uncommon Opinions on Common Descent

Radical divergences amongst UD contributors
In this posting on Uncommon Descent Paul Nelson comments on an article in New Scientist. The article concerns “Horizontal Gene Transfer” between organisms, especially in the early days of unicellular life. The existence of HGT has the effect of modifying Darwin’s “tree of life” model to a “net of life”. Does this mean that Darwin’s original tree concept has been completely overthrown? New Scientist comments thus:

…the tree concept could become biology's equivalent of Newtonian mechanics: revolutionary and hugely successful in its time, but ultimately too simplistic to deal with the messy real world. "The tree of life was useful," says Bapteste. "It helped us to understand that evolution was real. But now we know more about evolution, it's time to move on."

Sensational eye catching headlines apart the tenor of the article is that the tree of life is, like Newton’s laws, a first approximation. It is a low resolution model of the descent structure of life, a structure that on closer look starts to break up revealing fibrils connecting the branches of the tree, thus making it less tree like and more net like. Horizontal gene transfer challenges the notion that common descent is an absolute rule. However, common descent as a low resolution phenomenon is still real; at least DaveScot, Paul Nelson’s fellow UD contributor thinks so. As I quoted in my last post Dave has said:

Common descent from one or a few ancestors beginning a few billion years ago has overwhelming evidence in support of it.

So, just as quantum theory succeeded in embracing systems successfully described by Newtonian mechanics the “net of life” concept must embrace the “tree of life” as a case observed under low resolution conditions. The “net of life” picture must approximate the tree of life picture seen at lower resolutions, just as quantum mechanics approximates Newtonian mechanics under the right conditions.

But on the subject of the ‘tree of life’ there seems to be little consensus amongst ID theorists. On the one hand we see DaveScot positing a history of common descent and on the other hand there is Paul Nelson who is a Young Earth Creationist who believes there is no history of life to explain: to him the clade structure of living things is not a product of a common descent but, presumably, an artifact of an act of Intelligent design creationism that took place little over 10,000 years ago. (re: “Evidence of common design” in my last post)

Once again we have here illustration of the difficulty that ID theorists have in reaching a consensus on the scientific heuristic to use in the research of the history of life. The premise that the generation of life requires special acts by an ID agent entails so many ways in which that agent could act that the possible interpretations of the data protocols proliferate. It’s no surprise then that the diversity of opinion amongst ID theorists ranges from evolutionary histories not dissimilar to the establishment picture (albeit with a very different concept of the mechanisms of evolution) through to YEC denials that there is in fact a history there at all. However, although the contributors on Uncommon Descent are a loose alliance of theorists who as group don’t exactly know what they believe they certainly know what they don’t believe. So all you hardened evolutionists out there, do yourselves a favour and run for cover.

STOP PRESS 28th January
Looking at this post it does indeed look as though some evolutionists are running for cover.

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