Sudden Origins: Fossils, Genes, and the Emergence of Species

Despite the title, Darwin's Origin of Species doesn't really explain how new species are born. Scientists have been struggling with that thorny problem ever since its publication, and the recent revolution in molecular biology has turned up great piles of new evidence. Anthropologist Jeffrey H. Schwartz takes a close look at this evidence, as well as the more traditional paleontological material, in Sudden Origins: Fossils, Genes, and the Emergence of Species. He claims that the tide is turning in favor of "punctuated equilibrium"--the theory that species typically remain static for great lengths of time and then experience brief spurts of accelerated change--thanks in no small part to the discovery of homeobox genes.

These remarkable structures are the genetic equivalent of the proverbial butterfly wings that cause hurricanes halfway around the world--small changes can produce enormous effects. Homeobox genes regulate development and are remarkable similar between species and even between phyla--you share some with fruit flies, for example. By turning our attention toward embryology and development, Schwartz shows us that fossils can't tell the whole story, since much of it lies within the womb. He covers a lot of ground and stretches the reader's intellectual muscles; the scope of Sudden Origins and the greater understanding of Darwin's problem make the challenge well worth it. --Rob Lightner