On the Origin of Species

Lately, I have been reading On the Origin of Species on my iPhone. Although I must confess that I haven’t read the whole thing, in part because I already know how it ends (Fig. 1).

Fig. 1 I stopped reading before Darwin got to this part...

I doubt many people reading this post will need me to point out Darwin’s brilliance (although some people might!). Instead, I want to write about what struck me while reading the book.

It’s one long argument.

I was surprised that in many respects, On the Origin of Species reads more like a math paper than a biology paper; although variables and equations are scarce, Darwin carefully lays out a series of observations, assumptions, hypotheses and deductions in support of his theory of natural selection, much like a mathematician would present lemmas, corollaries and proofs.

Let us now take a more complex case. Certain plants excrete a sweet juice, apparently for the sake of eliminating something injurious from their sap: this is effected by glands at the base of the stipules in some Leguminosae, and at the back of the leaf of the common laurel. This juice, though small in quantity, is greedily sought by insects. Let us now suppose a little sweet juice or nectar to be excreted by the inner bases of the petals of a flower. In this case insects in seeking the nectar would get dusted with pollen, and would certainly often transport the pollen from one flower to the stigma of another flower. The flowers of two distinct individuals of the same species would thus get crossed; and the act of crossing, we have good reason to believe (as will hereafter be more fully alluded to), would produce very vigorous seedlings, which consequently would have the best chance of flourishing and surviving.

In the above passage, a couple phrases that I see almost exclusively in regard to mathematics are shown in bold. In most biology and physical sciences papers today, the primary aim is to report results rather than to engage in speculation, or to construct and test (and heaven forbid, disprove) a hypothesis. Indeed, I think a large portion of science today forgoes well-formed hypotheses in favor of mere questions.

To borrow from the passage quoted above, a typical researcher today would design an experiment to answer the question, “Do cross-pollinated plants produce more vigorous offspring?” and then simply report the results, “We found that cross-pollinated plants produce more vigorous offspring,” while offering a brief, hedged explanation, “This result might be attributable to the increased genetic diversity of the offspring. The genetic basis of this finding will be explored in future work.” The follow-up work would then be designed to answer the question, “Is there a genetic difference between pure and crossbred plants?”

Basically, in my fictitious research example, the Scientific Method is being followed, but in an extremely uninspiring way. In contrast, the best works extend beyond merely reporting results to form explicit testable hypotheses that logically follow from the experimental findings, rather than leaving the hypothesis implicit in the design of subsequent studies. For me,what makes On the Origin of Species so enthralling is its presentation of the science known at the time to construct an extremely far-reaching theory.

Seeing the foundations of modern biology

Reading On the Origin of Species, I was struck by the extent to which it resembled a road map of modern biology. For example, Darwin notes that crossing two individuals that differ to a certain extent will lead to beneficial variations, while crossing two individuals that differ too greatly will produce sterile offspring or none at all. On this point, he writes, “Both series of facts seem to be connected together by some common but unknown bond, which is essentially related to the principle of life.” Of course, modern readers recognize this “unknown bond” as DNA. Darwin presents his theory comprehensively, but often notes its shortcomings. Notably, these gaps have since been filled by work in fields such as molecular biology, population genetics, anthropology and paleontology.

British spelling, archaic spelling, and outdated notions

• mongelise
• ruta-baga
• male alligators have been described as fighting, bellowing, and whirling round, like Indians in a war-dance
  

  Fig. 2 Darwin, that's not PC dude!

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