The Bactra Review   The Causes of Evolution
A lot has been learned, much of it very recently indeed, about the genes which regulate bodily form, particular the Hox genes, which are astonishingly similar in all metazoans. But all this work has, quite properly, treated the physico-chemical mechanisms of pattern formation as so many black boxes, and left obscure how those mechanisms are controlled by the genes (as they must be). For a brief review of Hox genes and kindred issues, see Sean B. Carroll, ``Homeotic Genes and the Evolution of Arthropods and Chordates'', Nature 376 479--485 (10 August 1995); or, rather more leisurely, Rudolf A. Raff, The Shape of Life: Genes, Development and the Evolution of Animal Form (University of Chicago Press, 1996). [With thanks to Aryaman Shalizi for the Carroll reference, and impressing me with the need for this clarification.]