Of Terms in Biology: Teleonomy
by Roberto
Read the following two phrases.
⦁ In the presence of lactose, E. coli induces β‑galactosidas in order to use the sugar.
⦁ In the presence of lactose, E. coli induces β–galactosidase and thereby uses the sugar.
Which one would you use? Do you see the fundamental difference between them? By replacing "in order to use" with "and thereby uses" we do not answer the important question of why β–galactosidase is induced; what is the purpose of β
–galactosidase? In a recent post I foreshadowed that I'd tackle this subject, here it is.
Fig. 1. Colonies of Lac+ E. coli grown on MacConkey lactose agar. Source
As scientists we tend to avoid discussions that bring forth purpose. Why? There may be good reason. The argument that something is so because it has a purpose – call that teleology – is not favored among biologists because we see it loaded with religious belief. Still, some deep-thinking biologists saw a need to describe the apparent purposefulness of structures and functions of living beings through a philosophical outlook. In 1958 Colin Pittendrigh (a pioneer in chronobiology), reacting to this widespread dodging of the question of purpose, suggested the use of "teleonomic, in order to emphasize that recognition and description of end-directedness does not carry a commitment to Aristotelean teleology." Think of teleonomy as the argument that apparent purposefulness in living organisms is the result of processes like natural selection.
Two influential players in the early days of molecular biology, Bernard Davis and Jacques Monod, felt strongly enough about "teleonomic" that they chose to use the word in the title of two important publications. These serve as "bookends" in the volume of papers presented at the Cold Spring Harbor Symposium on cellular regulation in 1961, a year that brought remarkable advances in molecular biology (Opening Address: The Teleonomic Significance of Biosynthetic Control Mechanisms by Davis, and General Conclusions: Teleonomic Mechanisms in Cellular Metabolism, Growth, and Differentiation by Monod and Jacob). Why their interest on teleonomy? Davis spells it out nicely in his paper:
"As in all discussions concerned with ecological or physiological significance, this paper has had a strongly teleological flavor. Most biologists, of course, in using the term teleology to denote the development of valuable structures and mechanisms, understand implicitly that they have in mind natural selection as the responsible agent, rather than the divine foresight of the original definition. However, the term still raises uneasy doubts concerning the theological bias of its user, and so I would like to support the recent proposal by Pittendrigh (1958) of the term teleonomy to make explicit the shift in the meaning of teleology as used by the modern biologist."
In Chance and Necessity: Essay on the Natural Philosophy of Modern Biology, Jacques Monod assigns extreme importance to teleonomy. He argues that a "fundamental characteristic" of all living beings is that they are "objects endowed with a purpose or project, which at the same time they exhibit in their structure and carry out through their performances." In his view, this characteristic distinguishes living beings from all other structures and gives it a name, "we shall call (it) teleonomy."
These scientists thought deeply about life and put down in writing many of their thoughts. As such they remain influential to this day. I like the concept of teleonomy and the thinking that went behind it. But clearly, it never gained much traction, never became a household term among biologists. Why? I'll let you ponder on the answer to that question.
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