From far, from even and morning
From far, from eve and morning
And yon twelve-winded sky,
The stuff of life to knit me
Blew hither; here am I.
Now - for a breath I tarry
Nor yet disperse apart -
Take my hand quick and tell me,
What have you in your heart.
Speak now, and I will answer;
How shall I help you, say;
Ere to the wind's twelve quarters
I take my endless way.
A.E. Housman, A Shropshire Lad, stanza 16, 1896
From the Nonliving, Life?
Biochemists study life at the molecular level. Their main concern is how molecular structure produces biological function. A natural question arises. Where did these complex molecules originally come from?
Analysis of the chemistry of living organisms reveals that this poem's metaphor about the origins and nature of life is wonderfully apt:
The stuff of life to knit me
Blew hither; here am I.
The picture of life that emerges from scientific analysis down to the molecular level is one of beautifully intricate structure that, it appears, just happened! It happened in a quite natural but wholly unpredictable manner as the consequence of the properties of atoms, and of the greater survivability of molecules that are inherently more stable, and that can even crudely make copies of themselves. Crude self-copying—that is, copying with errors—occasionally results in molecules that are even better self-copiers, and thus more likely to survive. The result is that the more stable and more able self-copiers become the most common molecules. But even they are not perfect copiers. Slightly more sophisticated copying schemes and supporting functions appear rarely, but are preserved. In essence, imperfection trumps perfection in a changing world.
Life just happened, but it did not happen in one giant, unlikely leap from simple to complex, from non-living to living. Science’s most convincing models of possible origins of life and subsequent evolution suggest that the small, relatively likely increments of heritable variation survive and become common when they result in even slightly higher rates of reproduction than their predecessors. Very slight, almost inevitable changes add up to what superficially seems miraculously complex.
The intricate structure of biological molecules does not just underlie function, it establishes function. The properties of substances, the courses and rates of even the most complex processes—movement, reproduction, consciousness, identity, love—all depend on molecular structures and interactions. To me, knowledge of the molecular basis of these processes makes them even more wondrous and beautiful.
In the grand scheme of the universe, each of us is here for only a moment. The lives of the molecules that compose us are even more fleeting. When you look at a table of turnover rates of biomolecules, sometimes expressed as their half-lives (the time it takes half of them to be used and replaced) you find that all the molecules in your body are relatively short-lived. Phospholipids in the brain, components of the membranes of nerve cells and the cells that enwrap them, have a half-life of 200 days, placing them among the longest-lived organic substances in your body (aside from connective tissue and bone). Fifty percent of your muscle protein is degraded and replaced every 30 days. For liver protein it's only five or six days, while the half-life of glycogen (starch) in muscle and liver is only 12 to 24 hours. Even as you tarry "for a breath", your molecules flow through you like water; you are only in part the person you were yesterday. You as a recognizable entity may not "disperse apart", but you are almost illusory from this perspective.
The narrator of the poem expresses a sense of urgency:
Take my hand quick and tell me,
What have you in your heart.
And with
Speak now, and I will answer;
How shall I help you, say;
expresses an endearing sentiment about how we might make use of our short burst of existence. What better can we do than be of help?
The atoms that compose you now have been part of many other objects, and will move on to be part of many more, both inanimate and living. Structural biologists are fascinated with how the molecules of life arise from what blows hither, how they function, and how they are discarded as wastes that will blow thither to play important roles in other lives.
Footnote, and another Housman poem
One thing about this poem that puzzles me is the meaning of "the wind's twelve quarters". After some research, I am no closer to satisfaction about its meaning. One of the (many) meanings of quarter is 'a point of the compass, particularly as a direction from which wind blows.' But compass points number either 4 (N, E, ..., the cardinal points), 8 (N, NE, E, ...), 16 (N, NNE, NE, ENE, E, ...), or 32 (N, N by E, NNE, NEbN, NE ...). In the 16-point compass, there are 12 non-cardinal points, but why leave off the cardinal points when speaking of all the wind's directions?
Unlike compasses, whose points always number 4 or 8 or 16 and so forth, a clock has twelve divisions, and analog clocks and watches can easily be used as compasses. (In the northern hemisphere, hold the watch face horizontal, and point the hour hand towards the sun. The line halfway between the hour hand and 12 will point south.) This handy type of compass might well have been used by soldiers on the battlefield. War and its pointlessness is a theme in some of Housman's poems.
From Last Poems, 1922:
Astronomy
The Wain upon the northern steep
Descends and lifts away.
Oh I will sit me down and weep
For bones in Africa.
For pay and medals, name and rank,
Things that he has not found,
He hove the Cross to heaven and sank
The pole-star underground.
And now he does not even see
Signs of the nadir roll
At night over the ground where he
Is buried with the pole.
The sky gives this poem its feeling of place, and gives to Africa a remoteness that makes the narrator's friend seem appallingly far away. The works of many poets reveal their knowledge of, and interest in, science and nature. Do you know your astronomy well enough to follow this poem?
