In search of the Laws of Biology

Image Credit: Technische Universiteit Eindhoven, Systems Biology Group

“How appropriate is it to look for all-encompassing laws to describe the properties of biological systems? By its very nature, life is both contingent and particular, each organism the product of eons of tinkering, of building on what had accumulated over the course of a particular evolutionary trajectory. Of course, the laws of physics and chemistry are crucial. But, beyond such laws, biological generalizations (with the possible exception of natural selection) may need to be provisional because of evolution, and because of the historical contingencies on which both the emergence of life and its elaboration depended”. — Evelyn Fox Keller, A Clash of Two Cultures.

“In DSO [Defence Sciences Office], we refuse to believe that biology’s descriptive complexity is mathematically intractable. Moreover, there is far more than just biology at stake. If we can develop the tools to understand systems as complex as biology, we can also apply those tools to design complex technological systems, materials, structures, and devices, and even expand our understanding to the dynamics of social networks”. — Benjamin Mann, Defense Advanced Research Projects Agency (DARPA), Through a Mathematical Looking Glass.

The Laws of Physics, especially Newton’s Laws are known to many. But what about the “Laws of Biology”? The biological world is the ultimate complex system. It streches from scales as small as the width of a protein alpha-helix (0.5 nanometres) to the entire biosphere (Earth’s equator is 12,756 km). Keeping aside for a moment the mind-boggling scales that would result from including astrobiology, that’s some 16 powers of ten in spacial scales. Timescales are another story altogether. From femtosecond molecular dynamics to the age of the Earth (0.14 exaseconds), biological time spans some 33 powers of ten in temporal scales. So, with processes taking place over such a vast array of spatial and temporal scales, can we even conceive of finding universal Laws of Biology?

The answer, seems to be yes. And the key appears to be found in systems biology. Systems biology is a whole-istic system-level based approach to understanding biology. Its approaches look to integrate across different levels of structure and scale from components, building blocks (or patterns) and (biologically) functional modules to the large-scale of organization of the system (e.g. the cell) as well as across phases of processes, linking the insights from the many “omics” like genomics, proeomics and metabolomics. It aims to analyse the hieraerchical structure and the spatio-temporal dynamics of the underlying network of interactions. In short, systems biology is network biology. Being a fan of fuzzy logic, I tend to subscribe to the view that systems biology should include both bottom-up and top-down approaches:

Image Credit: BioITWorld.com

as brilliantly described in a 2004 article by Michael Leibman in BioITWorld.com. The question is, how does one go from an undestanding of the system to Laws? In physics, we seek the fundamental scaling constants that suggest principles operating across all scales. A new article entitled “Laws of Biology: why so few?” by Pawan Dhar of the RIKEN Advanced Sciences Institute and Alessandro Giuliani of the Department of Environment and Health, Istituto Superiore di Sanita in Rome published in the journal of Systems and Synthetic Biology, has began down exactly this path. What struck my eye was a table they produced for the rules governing features of different scales:

Image Credit: P.K. Dhar & A. Giuliani, Syst Synth Biol (2010) 4:7–13

If scientists can understand how these laws inter-relate and interact across the scales of network biology, I personally believe that the Laws of Biology will be obtainable.