The second is author and philosopher of science Stephen C Meyer. The author of two extraordinary books on this subject.
The first book is entitled The Signature in the Cell, in which Stephen develops a comprehensive argument that demonstrates to the reader that the functional biological information within the cell cannot be explained by any of the currently held purely materialist explanations for the origin of life. In fact he progressively goes through each of the proposed material explanations and clearly shows exactly why they are inadequate.
His second work, Darwin's Doubt, explores the practical problems exposed by the absolute necessary of the additional biological information needed to construct a new animal body plan. And in particular he focuses on the what can be learned from the sudden appearance of virtually all the basic animal body plans that occurred in the comparatively short period of time known as the Cambrian Explosion.
I particularly was absorbed by chapter 13 where Stephen discuses the implications of the ground breaking mutational experiments on fruit flies carried out by Christiane Nüsslein-Volhard and Eric Wieschaus, as well as the work of Eric Davidson who has pioneered the elucidation of Embryonic Developmental Gene Regulatory Networks. (dGRN's) This is the genetic circuitry that controls the switching pathway from a single fertilized cell through to a fully formed animal.
Davidson's work has shown that every single species has its own unique dGRN that appears to be absolutely set in stone. With the exception of very minor changes that occur toward the end of the process that effect trivial small scale features, every attempt to artificially modify / mutate these networks always produces catastrophic results.
The early hopes to have discovered a functional mechanism capable of changing embryonic development to produce a radically new body plan/ species has been dashed. dGRN's have instead proven to be a very powerful stabilizing force preventing major changes in a basic body plan. There is apparently no way these control networks can be modified a step at a time (in a Darwinian fashion) because they are organised in an interconnected hierarchical way. If the fixed pathway is interrupted embryonic development always fails.
"The overall control principle is that the embryonic process is finely divided into precise little “jobs” to be done, and each is assigned to a specific subcircuit or wiring feature in the upper level dGRN. No subcircuit functions are redundant with another, and that is why there is always an observable consequence if a dGRN subcircuit is interrupted. Since these consequences are always catastrophically bad, flexibility is minimal, and since the subcircuits are all interconnected, the whole network partakes of the quality that there is only one way for things to work. And indeed the embryos of each species develop in only one way."