Monday, June 10, 2013
Organisms Are Not Machines
One of the most brilliant essays on the history of science that I ever read was Adam Smith’s ‘History of Astronomy’. Smith explains the difference between ancient or classical astronomy and modern astronomy as a difference in metaphors. For the ancients, the central metaphor was natural growth. They thus understood the heavens as essentially biological phenomena writ large. For moderns, the central metaphor is the machine. In the course of his essay, Smith presents an account of human understanding in distinctly mechanical terms.
We want our understanding to move from the phenomena to the explanation as smoothly as possible, so we build our explanations as we would build a ramp for a rolling ball. Gaps in the ramp require the ball to jump violently from one part to another, thus creating shock. Analogously, gaps in explanation produce the shock of surprise, which is unpleasant. So we try to build a continuous set of ramps in our explanations over which the understanding can flow smoothly.
Of course, Smith’s point included a note of caution. His mechanistic account of human reason, however serious one might take it, is still just a metaphor. One cannot take it seriously, but it is brilliant nonetheless.
Tonight I read Steve Talbott’s essay “The Unbearable Wholeness of Beings”, in The New Atlantis. It is a very strong critique of mechanism in biology. Talbott argues that modern biologists use two distinct sets of terminology, one appropriate to physics and chemistry and the other to living organisms; however, they do not recognize that the two languages are distinct or bother to carefully define their terms and sort out the differences. This, he thinks, results in profound confusions.
Think first of a living dog, then of a decomposing corpse. At the moment of death, all the living processes normally studied by the biologist rapidly disintegrate. The corpse remains subject to the same laws of physics and chemistry as the live dog, but now, with the cessation of life, we see those laws strictly in their own terms, without anything the life scientist is distinctively concerned about. The dramatic change in his descriptive language as he moves between the living and the dead tells us just about everything we need to know.
No biologist who had been speaking of the behavior of the living dog will now speak in the same way of the corpse’s “behavior.” Nor will he refer to certain physical changes in the corpse as reflexes, just as he will never mention the corpse’s responses to stimuli, or the functions of its organs, or the processes of development being undergone by the decomposing tissues.
Virtually the same collection of molecules exists in the canine cells during the moments immediately before and after death. But after the fateful transition no one will any longer think of genes as being regulated, nor will anyone refer to normal or proper chromosome functioning.
Talbott points out that the mechanistic models that once seemed so promising in biology have been demolished. The simple line of causation from gene to protein to trait certainly fit Smith’s model of a series of ramps. We know understand that that model is hopelessly simplistic. There are innumerable feedback loops between genes and their products and profound influences on each process exercised by the various systems that make up any organism. Even at the level of a single cell, the operation is vastly complex. Organisms are not machines.
Here is the heart of the matter: The parts of a clock are put together in a certain way; the parts of an organism grow within an integral unity from the very start. They do not add themselves together to form a whole, but rather progressively differentiate themselves out of the prior wholeness of seed or germ. They are growing even as they begin functioning, and their functioning is a contribution toward their growing. The parts never were and never are completely separate, never are assembled. A specific bit of food taken in from outside never becomes some new, recognizable part, added to the rest; rather, it is metabolically transformed and assimilated by the ruling unity that is already there. The structures performing this work, such as they are, are themselves being formed out of the work. Does any of this sound remotely like a machine?
When, on the other hand, we do build machines, we impose our designs upon them from without, articulating the parts together so that by means of their external relations they can perform the functions or achieve the purposes we intended for them. Those same relations give us our explanation of the machine’s physical performance.
He identifies three themes that distinguish organisms from machines. One is the relationship between the parts and the whole. In machines, the functioning of the whole is a simple sum of the action of all the parts. The organism is imposed from outside by the designer. Organisms are different.
The form, existence, and activities of the parts depend upon, and arise from — are in some sense caused by — the whole, which is therefore expressed in one way or another through every part. This is much like the relation between individual words and their context — which is not surprising, since language is itself an expression of organic life.
A machine has no agenda; only the manufacturers and operators have agendas.
Biological activities are carried out as if “with a view toward” or “for the sake of” some end. The organism “aims” to develop and sustain itself as a being with its own particular character.
While a machine may incorporate feedback loops, the operation is still a linear process that proceeds from the actions of the parts. In an organism, the parts are what they are because of the feedback loops.
To give an archetypal example, as the embryo polarizes into anterior and posterior, each pole is not only “opposite” to the other, but necessarily implied in the other. Each pole is properly formed only by virtue of the other’s being formed. Neither is a unilateral cause of the other.
Most interestingly, Talbott argues that the failure to recognize non-mechanistic character of living organisms leads many biologists to attribute mysterious powers to such things as DNA.
To say, as Nobel laureate Max Delbrück once did, that DNA could be conceived in the manner of Aristotle’s First Cause and Unmoved Mover, since it “acts, creates form and development, and is not changed in the process” — well, that’s a stupefying blind spot, a blind spot that to one degree or another dominated the entire era of molecular biology through the turn of the current century. It was already recognized and warned against by the German botanist Fritz Noll in 1903, who pointed out how (in E.S. Russell’s paraphrase) “the chief theorists have tried to solve the problem of development by assuming a material and particulate basis [today’s ‘gene’], without however attempting to explain how the mere presence of material elements could exert a controlling influence on development. They have been forced to ascribe to such abstract material units properties and powers with which they would hesitate to credit the cell as a whole.”
Weiss emphasizes very much the same point: because there is no possible way to make global sense of genes and their myriad companion molecules by remaining at their level, researchers have “simply bestowed upon the gene the faculty of spontaneity, the power of ‘dictating,’ ‘informing,’ ‘regulating,’ ‘controlling,’ etc.” And today, one could add, there is at least an equal emphasis on how other molecules “regulate” and “control” the genes! Clearly something isn’t working in this picture of mechanistic control. And the proof lies in the covert, inconsistent, and perhaps unconscious invocation of higher coordinating powers through the use of these loaded words — words that owe their meaning ultimately to the mind, with its power to understand information, to contextualize it, to regulate on the basis of it, and to act in service of an overall goal.
This strikes me as quite correct. Organisms are Aristotelian wholes. Unlike machines, the organism strives to maintain its being by controlling and incorporating subordinate organisms and cells, each of which is trying to do the same. We have come a long way beyond Aristotle’s biology only to arrive at Aristotle’s biology.