It’s Not Rocket Science

I receive a number of daily newsletters. Among them is one from, a website that serves as a clearinghouse for news on various scientific fronts. The stories are generally brief, rarely very technical, and their purpose is simply to alert the reader to the fact that that some new development or other has occurred in the field at hand; the curious reader may then, having been given the scent, follow it to its source on his own initiative. The whole thing is usually very professionally done, and is an excellent way to keep abreast of current events in science and technology.

Imagine my disappointment, then, to observe that Darwin’s theory of evolution by natural selection, the utter incomprehension of which we may sadly take as a “given” among its many detractors in religious circles, is also a source of confusion, even at the broadest and most superficial level, to the editors of the Physorg newsletter. I refer to the following headline, found atop a story in yesterday’s issue:

Do galaxies follow Darwinian evolution?

What is it that bothers me so? Read on.

The confusion here has to do with the use of the heavily freighted word “evolution”. This word, which has unfortunately become synonymous in many minds with Darwinism, simply means to unfold or unroll, and was already overloaded in Darwin’s time. Here is the entry on “evolution” from the Online Etymology Dictionary:

1641, “to unfold, open out, expand,” from L. evolvere “unroll,” from ex- “out” + volvere “to roll” (see vulva). Evolution (1622), originally meant “unrolling of a book;” it first was used in the modern scientific sense 1832 by Scot. geologist Charles Lyell. Charles Darwin used the word only once, in the closing paragraph of “The Origin of Species” (1859), and preferred descent with modification, in part because evolution already had been used in the 18c. homunculus theory of embryological development (first proposed under this name by Bonnet, 1762), in part because it carried a sense of “progress” not found in Darwin’s idea. But Victorian belief in progress prevailed (along with brevity), and Herbert Spencer and other biologists popularized evolution.

We may speak quite properly of the “evolution” of an idea, or a political system, a recipe, or the like, meaning, by such use of the term, the ways in which the subject changes over time. This is in fact the point of this article about the development of galaxies; the matter at hand is an attempt to understand how much of a galaxy’s future appearance is determined by its initial conditions, and how much by the influence of its local environment. We read:

The ‘nature versus nurture’ debate is a hot topic in human psychology. But astronomers too face similar conundrums, in particular when trying to solve a problem that goes to the very heart of cosmological theories: are the galaxies we see today simply the product of the primordial conditions in which they formed, or did experiences in the past change the path of their evolution?

In a large, three-year long survey carried out with VIMOS, the Visible Imager and Multi-Object Spectrograph on ESO’s VLT, astronomers studied more than 6,500 galaxies over a wide range of distances to investigate how their properties vary over different timescales, in different environments and for varying galaxy luminosities. They were able to build an atlas of the Universe in three dimensions, going back more than 9 billion years.

This new census reveals a surprising result. The colour-density relation, that describes the relationship between the properties of a galaxy and its environment, was markedly different 7 billion years ago. The astronomers thus found that the galaxies’ luminosity, their initial genetic properties, and the environments they reside in have a profound impact on their evolution.

Notice the reliance on biological metaphor here. The problem is likened to the study of human psychology, and we are asked, when considering the structural “evolution” of galaxies, to take into account not only their “genetic properties”, but also the relative impact of “nature versus nurture”.

We are always tempted to think metaphorically; indeed, a facility for metaphor is a hallmark of the insightful mind. But we must not be careless, and we must keep in mind that excessive reliance on a sturdy and productive metaphor can easily lead us into error.

While galaxies may indeed evolve, in the sense of changing over time, there is nothing Darwinian about any of it. Darwin’s great insight applies only to one class of entities: those that make copies of themselves, and which send their progeny out to make their way in the world, with varying success. (As Gould so aptly put it, “Variation proposes, selection disposes.”) It is not the individual that evolves in the Darwinian sense, but its lineage. Essential for the process is copying that is faithful enough to ensure continuity, but which allows for variation, either through occasional errors or a shuffling of genes between generations. Galaxies — quite obviously, we might have hoped — do not qualify.

This is not to say that there might not actually be some sense in which Darwinian evolution — the real thing — could occur at cosmological scales. Astrophysicist Lee Smolin, in his provocative book The Life of the Cosmos, makes an audacious suggestion regarding black holes as agents of replication and variation (the explication of which would be too much, I’m afraid, for this evening’s post). But to see even the editors of a respectable scientific newsletter drawn offsides in this way is, to say the least, a bit dispiriting, and if you’ve been hoping that Darwin’s theory, arguably the greatest idea in the history of science, might gain broader understanding and acceptance in this benighted culture, it does not augur well.

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