September 22, 2004 | David F. Coppedge

Cell Exhibits Robust Engineering Design

An international team of biotechnologists writing in the journal Cell1 thinks biologists need to focus more on the concept of robust engineering design. The abstract sounds like something out of an Intelligent Design Movement paper:

Robustness, the ability to maintain performance in the face of perturbations and uncertainty, is a long-recognized key property of living systems. Owing to intimate links to cellular complexity, however, its molecular and cellular basis has only recently begun to be understood. Theoretical approaches to complex engineered systems can provide guidelines for investigating cellular robustness because biology and engineering employ a common set of basic mechanisms in different combinations. Robustness may be a key to understanding cellular complexity, elucidating design principles, and fostering closer interactions between experimentation and theory. (Emphasis added in all quotes.)

In another sentence, they say: “cellular complexity appears to arise mainly from robustness as a design goal.” Any Darwinian worried about this story would quickly be assuaged, however, by the ubiquity of the “E” word: “It has long been recognized that this robustness is an inherent property of all biological systems and is strongly favored by evolution,” they claim. How this robustness actually came about, though, they have no idea:

Despite this central role in biology, there is still a limited understanding of what robustness precisely is and how it is accomplished at the cellular or molecular level (Hartman et al., 2001). A major reason is that robustness and the apparent complexity of cellular systems are intimately linked and, therefore, both are difficult to understand.

The authors investigate mathematical models of robustness, and ways that biologists might get a grip on how robustness evolved in living systems. Surprisingly, they speak of “engineering design” and “evolved design” frequently in the same sentence:

In both biology and advanced technology, the primary function of a system is usually robust to a wide range of perturbations, yet these systems can show extreme fragility toward other (even seemingly much smaller) perturbations and/or other functions. This coexistence of extremes in robustness and fragility (“robust yet fragile”) perhaps constitutes the most salient feature of highly evolved or designed complexity. Human-designed technology has well-understood mechanisms, which are deliberately hidden from the user. In contrast, we have little systems level understanding of biological complexity. Here, we argue that by combining the fragmented yet complementary knowledge in both domains, robustness and its associated tradeoffs offer a powerful perspective on biological complexity.

Another example: “Hence, in design or evolution, robustness, which is adapted to the intended function of a system and the associated uncertainties, must be carefully distributed.” They seem in awe at the levels of robustness in biology at times: “Perhaps the most astounding property of microbial metabolism is its evolved robustness to sustain survival and proliferation upon extensive environmental or genetic perturbations.” Living things employ several strategies to improve robustness: highly optimized tolerance, redundancy, feedback control circuitry, modularity, hierarchy and protocols, and other concepts from engineering. They think robustness as a research tool holds promise for evolutionary biology:

What is the tangible outcome of studying this issue for life sciences?  Such an overarching concept as robustness will certainly play several roles in biological research. It can be viewed as an overall evolutionary design principle or a scientific approach. More optimistically, it may be the panacea to the ailments affecting large-scale dynamic modeling of biological systems. At the least, in the hands of pragmatic researchers it can function as a tool producing testable biological hypotheses….
….The notion of cells being composed of robust subunits of limited autonomy simplifies modeling and abstraction of general properties. We can proceed from the detailed investigation of individual modules to their interplay and its consequence for overall systems performance. Robustness of cellular systems, hence, provides us with testable hypotheses derived from top-down studies and with opportunities for a more detailed bottom-up approach. Both approaches should finally converge.

1Stelling et al., “Robustness of Cellular Functions,” Cell, Volume 118, Issue 6, 17 September 2004, Pages 675-685, doi:10.1016/j.cell.2004.09.008.

Stand back: it won’t be a pretty sight when their heads explode. Their whole tale hangs on the belief that natural selection can perform miracles of engineering design on demand, whenever and wherever needed. Wait till they find out it is blind, deaf, dumb, and has no track record (see 08/03/2004 editorial, and the 07/23/2004, 06/09/2004 and 04/15/2004 headlines, for instance).  Stand back and turn around. The Engineer is in the opposite direction.

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