One of the more interesting questions about the history of science is whether certain theories are inevitable. Given a set of data and the prevalent intellectual environment, does it become difficult to avoid formulating, say, a theory of evolution by natural selection? Biology would seem to argue yes. After all, Darwin and Wallace, having been influenced by Malthus and Lyell, both spent time as naturalists in the Pacific and developed matching theories within about a decade of each other. Similarly, several people recognized the significance of Mendel's work within a few years of each other shortly after 1900, and they helped develop modern genetics at the same moment.

In a commentary in Nature Physics, MIT's Seth Lloyd considers whether this sort of fertile intellectual environment might extend across fields of study. He considers the fact that, at the same time Mendel's work on genes as discrete units of inheritance was being elaborated, quantum mechanics, with its emphasis on discrete energy states and behaviors, was also being developed. Is it possible that the intellectual environment was simply ready to see things in the form of quantized entities?

It's a fascinating question, but after touching on it peripherally, Lloyd drops it. Which is a shame, really, as the two theories developed in very different ways. Quantum mechanics has been wildly successful by extending the basic principles outlined at the start of the last century. Genetics, almost from the beginning, was successful largely because it started identifying all the ways that Mendel's basic principles are violated—things like genetic linkage, incomplete dominance, environmental influences, etc. Long before we gained the ability to sequence DNA, researchers had realized that genes were anything but discrete, as mutations in a single gene could produce wildly different phenotypes.

Instead, Lloyd contemplates what he terms the "digital gifts" that quantum mechanics has provided to biology. Some of these are just an odd form of the anthropic principle: if physics didn't have the properties it does, genetics wouldn't look like it does. Moving on, Lloyd argues that the information processing and randomness of quantum mechanics is echoed in gene expression and random mutation. Conceptually, he may have a point, but these biological processes take place at a scale where quantum mechanics doesn't apply. So, a large chunk of the essay seems to either be facile or wrong.

Ultimately, he does come back to an interesting question: has natural selection produced any biological structures that take advantage of quantum properties? The answer seems to be yes, as there are a number of cases where the quantum mechanical properties of some parts of a biological system help influence the system's behavior. Unfortunately, the behavior of one of these systems is described as performing quantum computations. Although that might be true in the formal sense, it will undoubtedly blur the issues for anyone who is trying to follow the development of useful quantum computers.

Finally, Lloyd comes to an idea that has been floated in the physics community recently. Although there is no real reason why some of the basic physical properties of the universe have the values they do, varying them can create universes that rapidly collapse or expand into nothingness. It's possible that universes spawn through some sort of regular process, and the equivalent of natural selection has eventually produced one that's stable enough for life to evolve. It's an interesting idea but, by this point, we're so far from Mendelian genetics as to have lost the plot.

The commentary was published as part of a series of articles in the March issue of the journal, motivated by this year's Darwin anniversaries. The remaining stories are a bit less grand in their approach, and harder to find fault with as a result. Still, it's not so much the overreach of attempting to link quantum mechanics and genetics that causes problems for this article. Instead, it's the fact that Lloyd glided past topics where he could have said useful things in order to focus on analogies that are strained past the breaking point.

Nature Physics, 2009. DOI: 10.1038/nphys1208