Quote of the Week
(August 4, 2025)

During development, the lens of an amphibian eye derives from the outer layer of cells in the developing head, at the point where an outgrowth of the brain comes into contact with the epidermal cells. But if an already developed lens is removed from one of these animals, something truly remarkable happens: a new lens forms from the upper edge of the iris, a structure that has nothing to do with lens formation in normal development.

And so, lacking the usual resources and the usual context for formation of a lens, the animal follows an altogether novel path toward the restoration of normal form and function.

One sometimes gets the feeling that a single, well-documented example of developmental plasticity of this sort, if taken seriously enough and contemplated deeply enough, could transform all of biology and deliver biologists from the worn-out fantasy of the mechanistic organism. But it doesn’t happen. As some have observed, paradigms of explanation, once established, can be very difficult to overturn merely by citing evidence contradicting them.

(from Chapter 10, “What Is the Problem of Form?”, in Organisms and Their Evolution — Agency and Meaning in the Drama of Life)

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