On a Bird Singing in Its Sleep
Robert Frost
Read the poem here.
Robert Frost, like many of the poets that grab my attention, often showed that he was a keen observer, with a scientist’s knowledge and with a persistent urge to ask why, and then to seek rational explanations. Understanding was thus a part of this poet’s sense of wonder. This poem appears to grow out of wondering whether a bird endangers itself when it sings out in the night. The narrator speculates that the risk might be reduced by the bird’s position low in a bush, the brevity of the song, and the nature of the sound that makes it difficult to locate (see Appendix at bottom).
Frost’s awareness of scientific explanations and principles shows plainly in this poem. Three scientific allusions stand out, the first to the nature of the bird’s sound (“sings ventriloquist”). The second is to DNA, the carrier of the genes we pass from generation to generation (“the long bead chain of repeated birth”). Finally, there is a clear allusion to mutations (“the interstices of things ajar”), the wonderful mistakes that are the raw material of evolution, and upon which natural selection acts.
Frost was an adept and talented teacher of Darwinian thinking. In the end, evolutionary reasoning gives his narrator the comfort of knowing that, if singing in this way endangered the bird enough to make it less likely to leave offspring, then such behavior—and the birds that exhibited it—would have long ago become extinct. If on the other hand, if such singing serves a benefit, such as tightening social bonds or confusing predators, then such night-singing birds would have an advantage. The poem’s last sentence is a very simple lesson in how evolution works, and how the best-adapted organisms become the most common.
Poem
Design
Robert Frost
Read the poem here.
Natural selection produces marvels, large and small. Camouflage is one of its most intriguing wonders. Among moths that visit white flowers, predators might fail to see the lighter-colored variants, so white variants might have a much better chance of success. Their offspring, many likely to be white also, succeed long enough to reproduce, and gradually, white moths visiting white flowers are the most common. The plant also has a stake in the success of moth visits, because they probably contribute to fertilization. But what works for prey works for predator. Moth predators include spiders, and they, too, are more successful if invisible to prey. So white converges on white, all by random variation of heritable traits, and by nature taking its selective course. At the root of such convergence are small changes in DNA sequence due to random mutation, mostly copying errors, wonderful mistakes that produce what looks superficially like meticulously designed change.
In “Design,”, the narrator presents us with a convergence of products of such selection. At the end, he flirts with the idea of a dark designer who cooked up this gruesome stew, perhaps merely to shock us. As we learn from Annie Dillard (see this Reflection), the details of selection can be appalling, and seeming in violation of human values. But Frost’s narrator tempers this flirtation by wondering, perhaps tongue in cheek, whether “design govern in a thing so small.” The narrator implies that the explanatory power of evolutionary theory reaches from the smallest to the largest aspects of life.
The convergence of white flower, white moth, and white spider, as well as the prevalence of birds that call quietly in the night, reminds me that variation and natural selection are at work in all things, and that our world is naturally equipped to produce intricate beauty, even without the need—thank you—for a designer.
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Appendix: How does a bird "sing ventriloquist"?
Location calls of birds—saying, in essence, ”Here I am.”—like those made at night, are usually pure tones (whistles—like the purple marks on the sonogram below). Such sounds, like cell-phone beeps, are hard to locate, and thus relatively safe to sing. On the other hand, distress or alert calls are mixed-frequency tones (chirps or checks—shown in blue), which are easier to locate, and often bring other birds in to scold or mob an intruder.
The sonograms present the frequencies of sound in the bird's as time passes left to right. Marks high on the chart represent high-pitched sounds. This song consists of a single tone (purple) followed by a series of chirps, in this case, chirps that quickly descend in pitch. Mixed tones like the chirps are easier to locate because of many easily detectable timing and phase differences in the different frequencies of sound waves reaching each ear.
