Quote of the Week
(June 2, 2025)

If there was any place where biologists expected a causal explanation of the organism to emerge clearly, it was in the study of Caenorhabditis elegans, a one-millimeter-long, transparent roundworm whose private molecular and cellular affairs may have been more exhaustively exposed than those of any other organism. The adult hermaphrodite has exactly 959 cells, each precisely identified as to origin and type: for example, 302 cells belong to the nervous system. The developmental fate of every somatic cell, from egg to adult, had already been mapped out by 1980. But this mapping and the associated molecular studies did not produce the expected explanations.

Sydney Brenner — who received a 2002 Nobel prize for his work on C. elegans — acknowledged that development “is not a neat, sequential process ... It’s everything going on at the same time.” Even regarding the carefully mapped cell lineages of this “simple” roundworm, “there is hardly a shorter way of giving a rule for what goes on than just describing what there is.” In other words, the only “rule” for the development of this worm is the entire developmental description of it.

When critics suggested he had not really come to an understanding of the worm, but had “only” described it, Brenner wisely responded, “I’m not sure that there necessarily is anything more to understand than what it is.” British science writer Roger Lewin quoted this remark by Brenner in an article titled, “Why Is Development So Illogical?” with the subtitle, “The more biologists learn about development, the less it appears that organisms are assembled by neat, sequential processes; we should not be surprised”. Actually, it’s not even true that organisms are assembled from pre-existing parts. They grow from within through processes of self-transformation, not mechanical assembly.

The difficulties of linear, causal explanation encountered by the C. elegans researchers were not accidental. You can’t explain an organism of meaning, and you don’t need to. You need only allow it, like any meaningful text, to speak ever more vividly and profoundly, in ever greater detail, so as to yield up its unique and unrepeatable story.

(from Chapter 9, “A Mess of Causes”, in Organisms and Their Evolution — Agency and Meaning in the Drama of Life)

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