Darwin's Doubt: The Explosive Origin of Animal Life and the Case for Intelligent Design

by Stephen C. Meyer

Normal development in any animal can be represented as an expanding network of decisions, where the earliest (upstream) decisions have greater impact than those occurring later. Regulatory genes and their DNA-binding protein products help to control this unfolding network of decisions—such that if regulatory proteins are altered or destroyed by mutation, the effects cascade downstream into the whole developmental process. The earlier the failure, the more widespread the destruction. Geneticist Bruce Wallace explains why early-acting mutations are thus overwhelmingly likely to disrupt animal development. “The extreme difficulty encountered,” he observes, “when attempting to transform one organism into another . . . still functional one lies in the difficulty in resetting a number of the many controlling switches in a manner that still allows for the individual’s orderly (somatic) development.”13 Nüsslein-Volhard and Wieschaus discovered this problem in experiments performed on fruit flies after their first Nobel Prize–winning efforts. In these later experiments they studied protein molecules that influence the organization of different types of cells early in the process of embryological development. These molecules, called “morphogens,” including one called Bicoid, are critical to establishing the fruit fly’s head-to-tail axis. They found that when these early-acting, body-plan-affecting molecules are perturbed, development shuts down. When mutations occur in the gene that...