Defining integrative biology

I n the official journal of the CNRS, the largest organization funding research in France, the new director of its Department of Life Sciences writes that ‘‘biology has to undergo a cultural revolution’’ [1] and, in a recent address to heads of its units, recommends that ‘‘integrative biology’’ be developed. This is one of several clear signs that many biologists now agree that to understand living systems fully—to answer the question ‘‘What is life?’’ [2]—requires the study not only of their molecules but also of their integrated functioning. However, there is no consensus as to what ‘‘integrative biology’’ really means and how it may be done. Is it to be the natural extension of a reductionism, which has been highly successful until now, or of a globalism, alias a holism without vitalist overtones, akin to macroscopic physics in which ‘‘somebody should be studying the whole system, however crudely that has to be done, because no gluing together of partial studies of a complex nonlinear system can give a good idea of the whole’’ [3]? Or could integrative biology transcend both reductionism and globalism? To advance the debate, we might first ask why it is becoming fashionable. Several microbial genomes have now been completely sequenced, and the exploitation of this vast body of information is a major challenge. Can this information be used, for example, to explain how a myriad different types of molecules and organizing processes interact to make a living cell or an organism? In our view, these and related explanations (concerning, for example, the origin of life or the evolution of ecosystems) are amongst the primary goals of integrative biology. Both reductionism and globalism are already evident in the inchoate integrative biology but under different guises. The reductionist aspect of integrative biology exhibits both the continuation of present reductionist approaches in molecular biology and biochemistry and the recruitment and application of reductionist approaches from fields such as polymer physics and other domains of physics and chemistry, in order to take into account the structural features and the reaction networks of living organisms and also the fact that they are open, dynamic systems. In this global reductionism, reductionist approaches from across the sciences are CAMILLE RIPOLL, JANINE GUESPIN-MICHEL, VIC NORRIS, AND MICHEL THELLIER