Quote of the Week
(September 9, 2024)

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.

(from Chapter 8, “A Mess of Causes”, in Organisms and Their Evolution — Agency and Meaning in the Drama of Life)

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