To Build a Worm: Where Undirected Evolution Runs into Severe Difficulties

In case anyone missed the punch line of my post yesterday, "Why St. Denis Should Be the Patron Saint of Evolutionary Theory," let me say it again as briefly as possible for the purpose of clarifying matters.

To build a worm like C. elegans from a single cell (the fertilized egg) requires a developmental pathway. In the case of C. elegans, that pathway has been observed in remarkable detail. Every cell in the adult has been traced, via cell division, back to the starting point in the egg.

Thu...