Niels Bohr and Max Delbruck believed that complementarity—such as wave–particle duality—was not limited to the quantum realm, but had correlates in the study of living things. Biological complementarity would indicate that no single technique or perspective allows comprehensive viewing of all of a biological entity's complete qualities and behaviors; instead, complementary perspectives, necessarily and irrevocably excluding all others at the moment an experimental approach is selected, would be necessary to understand the whole. Systems biology and complexity theory reveal that, as in the quantum realm, experimental observations themselves limit our capacity to understand a biological system completely because of scale-dependent “horizons of knowledge,” a form of biological complementarity as predicted by Bohr and Delbruck. Specifically, observational selection is inherently, irreducibly coupled to observed biological systems as in the quantum realm. These nested systems, beginning with biomolecules in aqueous solution all the way up to the global ecosystem itself, are understood as a seamless whole operating simultaneously and complementarily at various levels. This selection of an observational stance is inseparable from descriptions of biology indicates—in accordance with views of thinkers such as von Neumann, Wigner, and Stapp—that even at levels of scale governed by classical physics, at biological scales, observational choice remains inextricably woven into the establishment, in the observational moment, of the present conditions of existence. These conceptual shifts will not only have theoretical impact, but may point the way to new, successful therapeutic interventions, medically (at the scale of organisms) or environmentally/economically (at a global scale).
Theise, N. D. and Kafatos, M. C. (2013), Complementarity in biological systems: A complexity view. Complexity, 18: 11–20. http://dx.doi.org/10.1002/cplx.21453