Physicists Finding Perfection… in Biology — June 1st, 2009 by Biologic Staff
When we think of simple, elegant, unifying principles in science, we think of physics. It’s not surprising then that physicists who examine living systems are looking for principles of this kind.
And it seems they have found one. Simply stated, it is that biological processes tend to be optimal in cases where this can be tested. Life’s complexity can make it hard to pinpoint what “optimal” means, but sometimes physical limits provide a crisp definition. Because these limits cannot possibly be exceeded, they serve as an objective standard of perfection. Interestingly, in cases where it is clearly beneficial to edge right up to this standard, that’s exactly what life seems to do.
For decades enzymologists have recognized that certain enzymes are catalytically perfect—meaning that they process reactant molecules as rapidly as these molecules can reach them by diffusion. [1] That hinted at a principle of physical perfection in biology, but no one anticipated its breadth until recently. According to Princeton physicist William Bialek, one of the leading proponents of the emerging principle, “The idea of performance near the physical limits crosses many levels of biological organization, from single molecules to cells to perception and learning in the brain.” [2] He observes that “While it is popular to view biological mechanisms as an historical record of evolutionary and developmental compromises, these observations on functional performance point toward a very different view of life as having selected a set of near optimal mechanisms for its most crucial tasks.” [2]
Bialek is interested in determining whether this principle will continue to hold up as more and more biophysical systems are tested against it. But it’s also interesting to ponder how such a principle can be explained. In particular, which origins paradigm does it best cohere with—the Darwinian one or the design one?
Although the Darwinian mechanism has some capacity to optimize, perfection seems to be well beyond its reach. Its handicap lies in the kind of optimizer it is—a local one, not a global one. That is, it produces not the best solution to a problem but rather the best available solution—meaning available by chance to a species in which the problem has not yet been solved.
If it’s reasonable to think that a complex problem that hasn’t been solved at all is not even close to having been solved well (and it seems that it is), then surely the best available solution under such dire circumstances is not apt to be a good one. Even after all the available chance improvements are exhausted, you would expect to be left with something makeshift, far from perfect.
So, while most biologists like to think that Darwinism can deliver perfection, that notion evaporates very quickly under critical scrutiny. Now that perfection is becoming a recognized principle in biology, perhaps it’s time for biologists to join the physicists in grappling with it.