Reconstructionist molecular biology.

In the editorial inaugurating this journal, Levine (1989) pointed to a new reductionism in biology, which--unlike the old reductionism that led to specialization and isolation of areas concerned with different aspects of a complex biological problem--is providing a renewed sense of unity. This development is the result of widespread use of common experimental methodology and the emergence of signal transmission and differential gene expression as themes that are central to many areas of modern biology. I describe here a set of complementary developments in molecular biology that focus attention on the problems of complexity and organization. Simple examples are given that illustrate the difficulty of relating systemic behavior to the properties of the underlying molecular determinants, and the outlines of a general approach to this problem are presented. These developments, together with those highlighted by Levine, are leading us to a new, more integrative intellectual paradigm whose fruits will be the elucidation of fundamental issues concerning network function, design, and evolution that cannot be addressed by the current paradigm.