The Making of the Fittest

August 7, 2006
Picking up where scientists like Richard Dawkins have left off, Carroll, a professor of genetics at the University of Wisconsin–Madison (Endless Forms Most Beautiful: The New Science of Evo-Devo
), has written a fast-paced look at how DNA demonstrates the evolutionary process. Natural selection eliminates harmful changes and embraces beneficial ones, and each change leaves its signature on a species' DNA codes. For example, the Antarctic ice fish today has no red blood cells; yet a fossilized gene for hemoglobin remains in its DNA, showing that the fish has adapted over 55 million years by losing the red blood cells that thicken blood and make it harder to pump in extreme cold. The fish has developed other features that allow it to absorb and circulate blood without hemoglobin. . Carroll points out that by examining the DNA of these ice fish species, it's possible to map its origins as well as the history of the South Atlantic's geology. He also uses dolphins, colobus monkeys and microbes to demonstrate how deeply evolution is etched in DNA. While searches for the genetic basis for evolution are hardly new, Carroll offers some provocative and convincing evidence. 7 pages of color illus.; 50 b&w illus.