From Genome to Galaxy

On the day the most complete mapping of the human genome was announced, a human-made spacecraft landed on an asteroid named Eros, almost 200 million miles away from earth. Issuing commands into deep space, smart little specks on our planet slowed the craft’s descent onto the asteroid for a landing as gentle as a brisk walk, all the while transmitting pictures of the descent. This marvel occurred after the NEAR spacecraft, controlled by the Johns Hopkins University Applied Physics Laboratory, had traveled more than 2 billion miles over the past five years. As impressive as the expanses are, if the entire vault of outer space were a mile, we have traveled, by some conjectures, less than the length of the word at the end of this sentence.

The extremes of scale are scary. They are awesome as well. Even the meticulous genius Immanuel Kant was daunted by the starry skies above and the moral law within. What could possibly be the force adequate to move the cosmos and the human heart as well?


Such ruminations on outer space brought me back to a lecture on inner space I heard at the Catholic Health National Assembly last June in San Francisco. A brilliant lawyer, scholar and physician, Philip R. Reilly, who, among so many other accomplishments, has been president of the American Society of Law, Medicine and Ethics, compared the scale of knowledge that we have of our bodies to outer space itself.

If we could imagine, in looking at one of our cells, that we were on a spaceship 10,000 kilometers away from the earth, the earth would look as small as one of our cells might now look to us.

If, to enhance our inspection, we magnified our view by a couple of powers of 10, we would be able to spot the northeast quadrant of the United States. That would be akin to seeing one of the 46 chromosomes within that cell. With increased powers of magnification, zooming into the Great Lakes region, we could see a boat basin alongside Chicago. This is analogous to isolating one of our 30,000 genes, each with its thousands of bits of information.

Finally, if we could magnify our powers of inspection even more, now to see a blue patch on the back of a man’s hand in one of the boats, that patch would represent one of our DNA’s base letters, of which there may be 3 to 5 billion in the human genome, packed into each nucleus of the 100 trillion cells that make up a human body.

The alphabet of the genome is composed of only four letters, A, T, C and G, which actually represent four nucleotide bases, but since there are billions of them in each of our cells, they can orchestrate the entire symphony of an organic life. (If you wonder how you might get such diversity and complexity out of only four letters, remember that you can code every word of every book ever written with the Morse binary combination of dots and dashes.)

In this tiny, tiny, tiny world, some think they might find the human soul or the metaphorical key to unlock the secrets of our heart. (Both are impossible dreams, for if DNA were the sole key to personal identity, identical twins or clones would experience themselves as the same person.) Like other searchers inspecting the vast, vast, vast cosmos in the hope, perhaps, of finding the end of all things, our navigators of the genome have nothing to stop their search but the limits of space and time. Some fear this search, but I think it is as awesome and inspiring as their respective topics, the cosmos and the corpus. In both quests, there are perilous ethical challengesselection of preferred traits, destabilization of our delicately wrought genome, reckless eugenicswhich in future columns I will consider. But, as I think St. Thomas Aquinas would say, May the search go on.

At the end of all problems posed by science, no matter how vast the reach or interior the probe, I suspect that there will be found walls of mystery. It will be not only the mystery of human consciousness, so recalcitrant to materialist explanations, that can marvelously turn back upon itself so as to enable us to mount mighty triumphs of biology and neuroanatomy, and at the same time reach so far as to drop a hunk of steel on an asteroid millions of miles away.

More wondrously still, it will be the mystery that might finally draw us, this splendid species called humankind, so minuscule in the cosmos it examines and tames, to humbly acquiesce with Dante at the end of the Paradiso:

High fantasy lost power, and here broke off.
Yet, as a wheel moves freely, free from jars,
My will and my desire were turned by love.

The love that moves the sun and the other stars.

Note: Any unintended misstatements that this non-professional makes in the accounting of Dr. Philip Reilly’s analogy are most certainly my own. Two more recent and accessible treatments of the genome can be found in Matt Ridley’s Genome: The Autobiography of a Species in 23 Chapters and Evelyn Fox Keller’sThe Century of the Gene. A more extensive, challenging treatment, written by bio-ethicists, is From Chance to Choice: Genetics and Justice, by Buchanan, Brock, Daniels and Wikler.

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