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John Gerhart & Marc Kirschner - Cells, Embryos, and Evolution

Intended for advanced undergraduate or graduate programs, Cells, Embryos, and Evolution on the whole will not be for everyone. Chapters 2 through 9, especially, can be dense for someone without previous exposure to the subject. In light of the current 'intelligent design' rage, let's hope a well-written popular work, which covers the same basic topics, is being developed.

Despite the fact that those not very familiar with the subject will have much of the content go over their heads, this is perhaps the only place (in 1998 at least) that all this information is available in one, organized book. For that reason alone, it is an excellent reference.

My other complaint (in addition to the possible comprehension difficulty) is the evolution element is not always as prominently discussed and integrated as the title and preface suggest. Plenty of information on cells and embryonic development are covered but the evolution tie-in occasionally is lacking or at least not as strong as it could be.

There are several main themes in this textbook. Given the length, of over 600 pages, I will only go over a couple of them here. First is the conservation maintained in flexible biological mechanisms and organisms. As ironic as it may seem on the surface, conservation is a key part of the diversification process. While the morphology of species fills much of the imaginable spectrum (i.e. there is great diversity), the differences in genes, processes, body parts/positioning, and inter-cellular communication are relatively constant through millions of years of evolution. For instance, the three-dimensional structure of the a clam hemoglobin can be superimposed almost exactly on that of the 'same' myoglobin in a sperm whale. Likewise, with body plans, whether you are dealing with a goose, a mouse, a newt, a zebrafish, or Xenopus the site of the forelimb or pectoral fin is at the anterior boundary of the Hox-c6 and Hox-b8 expression compartments. Somewhat similarly, whether you are looking at a whale, a human, or a giraffe, you are looking at a species with seven cervical vertebrae. Of course each of those in the giraffe is longer than all seven of the human's combined.

The other main theme is that of the evolution of evolvability. Although individuals aren't selected to be able to 'better evolve', populations and species are. In addition, the systems that make up organisms (especially when the systems were in their infant stages hundreds of millions of years ago) are specifically selected for based on their flexibleness, versatility, and robustness. The immune system is one example that is gone over is ample detail.

Also of interest, but not necessarily main themes in the book, are things like the development of the nervous system (which relies on superfluous growth and functional selection rather than pre-programmed, exact genetic function), probable causes of the Cambrian 'explosion' (somewhat related to the evolution of evolvability above), time-dependent gene expression, and neural crest cells (which allow for 'rapid' diversification of the size and shapes of skeletogenic elements).

For those who are looking for a rebuttal to creationist propaganda, you will find tons of ammunition here. Besides the attacks that have been made by creationists on the immune system other topics like the evolution of eyes are discussed. Species like Anableps anableps, the 'four-eyed fish', and cubomedusan jellyfish, which have no brain but do have camera-type eyes (unlike the less useful reversed-retina human eyes), will leave creationists scratching their heads and wondering where their creator went wrong in creating humans. I don't think the authors intended the book to be a direct response to Michael Behe but their allusions to Black Boxes being opened in the final chapter let the reader know that the god-of-the-gaps theory Behe postulates is only plausible when all the evidence isn't carefully examined.

Cells, Embryos, and Evolution is essential for advanced students of the subject. The rest of us have many things to learn on the topic, but a text aimed at more general audience is needed. If you get nothing else out of this book you will at least get to view numerous photographs of mutants which can only be described as 'really cool'. ;)

from the publisher:
In Cells, Embryos, and Evolution the authors' ambition is to continue what Darwin started: to understand not only the influence of selection on the path of evolution but also the capacity of the organism to generate heritable variation upon which selection can act. Drawing on the understandings derived from molecular, cell and developmental biology in the past 20 years, John Gerhart and Marc Kirschner have begun to explain the origins of phenotypic variation and evolutionary adaptation from within eukaryotic cell biological and developmental processes. This has required them to confront the paradox of, on the one hand, deep cellular and molecular conservation and the extraordinary stability of body plans of the major metazoan phyla and, on the other hand, the rapid diversification of the anatomy and physiology of organisms. Cells, Embryos and Evolution is richly illustrated with examples drawn from modern palaeontology, developmental biology and cell biology. It sets out to establish a coherent basis for evaluating the role of cellular and embryological mechanisms in evolutionary change.

  • a ground-breaking text in the new subject of cellular evolution
  • written by two extremely distinguished authors
  • every cell biologist, molecular biologist and evolutionary biologist will want a copy of this book

    Contents (Chapter Titles)

    The surprising conservation of cellular processes; Contingency; Regulatory linkage; The exploratory behaviour of biological systems; Novelty; Conditionality and compartmentalization; Body plans; Axis specification and reproductive strategies; Developmental flexibility and robustness; Evolutionary diversification of the body plan; Evolution and evolvability [an error occurred while processing this directive]