What if there is genuine directionality in mutation? An important paper in PLOS Genetics addresses the subject, asking, “What is mutation? A chapter in the series: How microbes ‘jeopardize’ the modern synthesis.” The Abstract states:
Mutations drive evolution and were assumed to occur by chance: constantly, gradually, roughly uniformly in genomes, and without regard to environmental inputs, but this view is being revised by discoveries of molecular mechanisms of mutation in bacteria, now translated across the tree of life. These mechanisms reveal a picture of highly regulated mutagenesis, up-regulated temporally by stress responses and activated when cells/organisms are maladapted to their environments — when stressed — potentially accelerating adaptation. Mutation is also nonrandom in genomic space, with multiple simultaneous mutations falling in local clusters, which may allow concerted evolution — the multiple changes needed to adapt protein functions and protein machines encoded by linked genes. Molecular mechanisms of stress-inducible mutation change ideas about evolution and suggest different ways to model and address cancer development, infectious disease, and evolution generally.
Several years ago (I think in Italy), Michael Denton said to me, as we were chatting about genetic puzzles, “I think the premise of random mutation is due for re-examination.” I haven’t seen Michael recently, but I’ll raise a glass of wine to him tonight.
His point stemmed from his perception that much of the foundations of neo-Darwinian theory rested on Darwin’s philosophical insistence, inherited by his intellectual offspring in the 20th century, that the ultimate origins of adaptive complexity must be random events. See, for instance, Darwin’s correspondence with the Harvard botanist Asa Gray, a theist, where Darwin insisted throughout that variations arose randomly. And, in his autobiography, Darwin wrote, “There seems to be no more design in the variability of organic beings, and in the action of natural selection, than in the course which the wind blows.” If the case is otherwise, the consequences would be far-reaching.