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Biology could be simpler than we thought

We are huge believers in the value of simplicity. Unnecessary complexity wastes time.

Simplicity is useful and elegant–yet far from easy to achieve. And our resulting curiosity for all things simple leads us in many weird and wonderful directions. This week, we found a nice simplicity story in the field of biology.

Physicists from Newton to Einstein have long known that physics can be broken down into a few fundamental laws and systems–but what about biology? It was thought that intricate biological systems are inherently complex, but new research reveals that this might not be the case.

A new way of looking at biology

Biophysicist Ilya Nemenman from Emory University has identified key parameters that distill the behavior of several biochemical networks into simple equivalent dynamics. The potential applications of this research are wide-reaching; it is hoped that the findings could streamline the development of drugs and diagnostic tools by simplifying the research models used.

Nemenman, an associate professor of physics and biology at Emory, said, "It appears that the details of the complexity of these biological systems don't matter, as long as some aggregate property, which we've calculated, remains the same." He went on to add that the simplicity of the findings made it "a beautiful result."

Nemenman drew upon established principles, already used in physics, to inform his research. Using the example of air molecules moving about his office, he said:

"All of the crazy interactions of these molecules hitting each other boils down to a simple behavior: an ideal gas law. You could take the painstaking route of studying the dynamics of every molecule, or you could simply measure the temperature, volume and pressure of the air in the room. The second method is clearly easier, and it gives you just as much information."

Nemenman and his team wanted to identify similar parameters for the complex dynamics of cellular networks, which can involve thousands of variables among different molecules interacting with one another.

Kinetic proofreading

The research team wanted to answer a few key questions, including:

  • What determines which features in these networks are relevant?
  • If they have simple equivalent dynamics, did nature choose to make them so complex in order to fulfill a specific biological function?
  • On the other hand, is the unnecessary complexity a "fossil record" of the evolutionary heritage?

Nemenman and his team investigated these questions in the context of a kinetic proofreading (KPR) scheme. This is the mechanism used by a cell for quality control as it makes protein, and was predicted in the 1970s. It applies to most cellular assembly processes, and involves hundreds of steps – each of which may have different parameters.

Nemenman wondered whether this process could be described more simply: "Our calculations confirmed that there is, in fact, a key aggregate rate," he said. "The whole behavior of the system boils down to just one parameter."

Simple solutions

This means that we can now predict the error and completion rate of an entire system, by looking at a single aggregate parameter: "The larger and more complex the system gets, the more the aggregate behavior is visible," Nemenman said. "The completion time gets simpler and simpler as the system size goes up."

Nemenman is now building on his research, working with Emory theoretical biologist Rustom Antia, to apply the findings to immune cells. They are particularly interested in the malfunction of the immune receptors involved in most allergic reactions.

Every time a process is simplified, vital research can be done that much quicker.

"We may be able to simplify the model for these immune receptors from about 3,000 steps to three steps," Nemenman says. "You wouldn't need a supercomputer to test different chemical compounds on the receptors, because you don't need to simulate every single step – just the aggregate."

This research will save precious time for those investigating biological processes, and has vast implications for health research. Every time a process is simplified, vital research can be done that much quicker.

Financial institutions, especially investment managers, should embrace simplicity. Our obsession with the principle is therefore unlikely to dissipate anytime soon.  

Credit: © Science Picture Co./Corbis

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