The Plausibility of Life:Resolving Darwin's Dilemma-Mark Kirschner and John GerhardtQuote:
Reviewed by A. J. Petto
The diversity of life's forms...is so engaging and impressive that it's easy to overlook the other side of the coin:the continuity that connects all organisms. In fact, any evolutionary model that used only data on divergence and none on conservedtraits would fail to make any sense of the emergence of new species from ancestral ones. InThe Plausibility of Life, (these ) authors focus on a number of "conserved core cellular processes" that are shared by all living things. Their thesis is that the core processes represent successful innovations that are inherited by evolutionary descendants.
However, they argue that the success of these processes lies not in their highly specified functions, but in their abilities to produce quite variable outcomes under different environmental conditions.
In essence this is the negation of the "irreduscible complexity" argument of "intelligent design"...The authors show how a single molecule with a highly specific function can perform one entirely different under a different environmental condition. In otherwords, the molecular imperative for the cell is flexibility, not specificity. The apparent specificity that we observe is so reliably produced, they argue, because the genome is selected for adaptability. How else could complex organisms so full of complex biochemical and developmental pathways be produced with (such a small) genome.
The authors explore several examples to illustrate their points.(quite effectively). These include metabolic processes, bauplan evolution, and morphological specialization...(flight adaptations are included as examples of "weak linkage" and "exploratory behavior")...
In a number of well-documented cases, a protein produces a weak signal that produces a specific effect under a specific condition. The linkages between the form and function are "weak" and easily forged and/or broken without any significant genetic change in the organism. This allows new forms and pathways to be forged while retaining substantially, the same DNA sequence..
Exploratory behaviour is viewed from an organismal and a cellular level as the basis for the appearance of complex organization arising from simpler actions.(In this example , foraging by ants can seen to give rise to surficial structural elements that are retained by ants and passed on via evolution to later derivative forms such as wasps.
Conservation of core processes is a hypothesis by which the evolution of complex structures, what is now the "mousetrap argument of Mike Behe and Ken Miller" could, by conserved core processes have easily started "the mousetrap" out as a starting gate or a latch spring. ..In their view the conserved core process is geared to producing components, but the assembly and final configuration are anything but foreordained(Now remember, these are biological systems not human engineered ones, the mousetrap argument is in my opinion a stupid one on all sides)
Petto is a rather labored (and a bit pompous) reviewer who makes his point as clear as the Missouri. Ive tried to decipher some of the "Stute" speak. Kirschner and Gerhardt state in summation via an entire book , almost as an add-on to what Gould and Miller said before(although, in MHO they said it better)
Gould--"genes are not the driver of evolution , they are but the mere bookkeeping of change already occuring, Evolution of forms need not entail changes in the genome"
Ken Miller--"Evolution is taking whats already there and making it do something else"
