Another Once-Favored Alternative to ID Reduced to an Epitaph
Over at Biologic Institute, Director Douglas Axe highlights a new paper that brings clarity to the origin of life debate.
The paper's title is a diplomatic statement of its main conclusion: Lack of evolvability in self-sustaining autocatalytic networks constrains metabolism-first scenarios for the origin of life. It becomes clear on reading the paper that the word constrains is here being used euphemistically
Dr. Axe explains what this means for Darwinian explanations of the origin of life.
At the time, my work was focusing on the profound differences between the simple catalysis caused by small molecules and the elaborately orchestrated and stunningly efficient catalysis achieved by enzymes--the catalysts of life. Kauffman was equating complexity with the sheer numbers of chemical species and reactions, whereas my concern was with the mode of reaction. Since Kauffman's model employed reactions that were fundamentally simple, with no discernible prospect of rising above this, I saw no satisfactory connection between his model and life.
But the difficulty of explaining life's origin makes even hints of progress a big deal, and many saw in Kauffman's simple model the potential for something bigger. The reason for their optimism, I think, was expressed by Daniel Dennett around the time of Kauffman's writing: "Evolution will occur whenever and wherever three conditions are met: replication, variation (mutation), and differential fitness (competition)." The hope was that if autocatalytic networks can deliver those three things, then whatever they lack in comparison to modern life they can acquire through progressive evolution.
I think it's fair to say that the optimism has faded as the years have passed without anything like a convincing demonstration--at least nothing that could be called "autocatalytic metabolism." Now it seems things may be drawing to a close with a new paper by Vasas, Szathmáry, and Santos. Their work calls this whole notion of life starting with raw metabolism into question by seriously undermining the biological relevance both of Kauffman's conjecture and of Dennett's dictum.
Read the rest here.