O N BEING WHOLEHEARTED
What follows is not a broad review of the book, but rather a narrow selection of notes drawn mostly on a single theme. The book contains wide-ranging essays by five European scientists, with an introduction by my colleague at The Nature Institute, Craig Holdrege. I will refer to the text using page numbers and authors' last names. For chapter titles and full identification of the authors, together with ordering information, see the end of this article.
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Not so long ago, if I had been asked to visualize and describe the human circulatory system, my natural impulse would probably have been, first, to talk about how the blood consisted of plasma and various cells, such as red and white blood cells. Then I would have pictured a network of pipelines, larger or smaller, for transporting the blood in a complex loop throughout the body. And, of course, I would have told how the heart, with its tireless and wonderfully consistent pumping action, drives this entire, life-sustaining circulation throughout its course.
Unfortunately, my description would, in spirit and in substance, have been hopelessly misconceived. It would also have been quite respectable. Why? Because it is an essentially mechanical description, and mechanical descriptions of organisms, however misconceived, tend to get respect today. Even if we recognize their inadequacy in a particular case, we can't help thinking they give us the "right sort" of understanding.
I will have more to say later about the meaning of "mechanical". For now, let's take a look at the idea that the heart is a pump, propelling the blood around the body. You can decide for yourself how well the metaphor fits the reality.
A Pound of Muscle
Here is an elaboration of the heart-pump idea by a blood specialist who appears perfectly happy with it. The description occurs under the chapter heading, "Pumps and Pipes" in a 1973 book called Blood, by Earle Hackett, who at the time was a Fellow of the Royal Australian College of Physicians and President of the Royal College of Pathologists of Australia.
An impressive description. In fact, it almost seems designed to confute the mechanical metaphor it celebrates. But the quickest way to get much clearer about the metaphor is by looking not only at the heart, but also at the "pipeline" it supplies.
There are 6,000 miles of blood vessels in the human body -- arteries, arterioles, capillaries, venules, and veins. (You will encounter estimates up to at least 60,000 miles.) That's enough pipeline to reach from New York to Los Angeles and back. So with my early, naive picture of the heart-pump, I was requiring less than a pound of specialized muscle to propel blood through tiny tubes running along one side of Interstate 80 from New York to the California shore, and then back again along the other side of the highway. Anyone who has experienced the muscular exertion required to drive a little bit of liquid through a few feet of narrow tubing (say, by blowing on one end of the tube) knows that the heart's New York to Los Angeles feat is not only impossible, but impossible by many orders of magnitude. Of course, in the body many of these pipes run in parallel, but this does not change the amount of work required.
But let's look a little closer. How narrow is our transcontinental pipeline? Very narrow. Most of its length consists of capillaries 0.3 millimeters or less in diameter. Some of these are so small that the donut-shaped red blood cells must flatten themselves in order to squeeze through. But this is not all. Our pipeline has the unfortunate habit of leaking. "Leaking" is an oddly mild word for it, however, since every day the pipeline loses about eighty times the total volume of blood plasma it contains (Lauboeck, p. 70). So our one-pound muscle not only has to overcome the astronomical resistance of a microscopic, 6,000-mile pipeline to Los Angeles and back, but it also has to irrigate the Great Plains along the way. Some pump!
You might be thinking, "If eighty times the total volume of blood plasma is being lost to the pipeline every day, this loss must be replaced somehow". So it must, and this is our first hint of all the other things going on quite unrelated to the idea of a pump. But this needs to wait. First, a quick listing of a few other observations that just don't fit a simplistic, mechanical image of the heart:
The prevailing science takes mechanism as the given and everything else, including movement, as the result. The truth may be more like the reverse of this.
What Drives the Blood?
By now you can surmise that, in asking what drives the circulation, we are up against a complex and organic set of interrelationships. The idea of a mechanical pump is not only hopelessly simplistic, but also flat-out misconceived. Certainly it's true that the muscular contractions of the left ventricle play a key role in the blood's movement through the arterial portion of the circulatory system (which accounts for about twelve percent of the blood volume as a whole). But, as we have seen, even here the pressure, volume, and heartbeat relationships are not at all characteristic of a typical pump. Nor is the phase of reverse flow. Moreover, the arteries themselves play a substantial role, dilating or shrinking as physiological conditions require, so as to accommodate more or less blood. The arteries also assist blood flow through the pulsing, wavelike muscular contractions of their walls.
On the other hand, approximately eighty-five percent of the body's blood flows without being under significant pressure. This "low-pressure system" -- which includes the capillaries, veins, right side of the heart, pulmonary (lung) circulation, and left atrium of the heart -- absorbs nearly all of a one-liter transfusion without causing any increase in blood pressure. The system counteracts pressure changes by relaxing in response to increased pressure and contracting in response to a pressure drop (Brettschneider, p. 27).
And what drives the blood through this low-pressure system? The factors are many, including lung movement, muscular exertion, and suction from the heart, but the central fact emerging from the book under review is that the metabolism as a whole propels the blood. While the heart's output volume is not directly proportional to heartbeat rate or blood pressure, it is proportional to the oxygen consumed in all the body's tissues. "Cardiac output is ... determined by the metabolic demands of the tissues" (Lauboeck, p. 65).
To understand this, recall that the capillaries are open to their surroundings. The fluids moving outside the blood vessels through the "extracellular matrix" make up a volume twice that of the total blood plasma. Fluid is continually passing in both directions between the primary circulatory system and the extracellular matrix, and also, for example, between the primary circulatory system and the kidneys -- so much so that, as we saw, the total volume of blood plasma must be replenished eighty times each day.
So it is this metabolically driven flow from the tissues into the blood vessels that sustains the greatest part of our circulation. "The force that causes the blood to flow into the heart is the result of work performed by the tissues continually replenishing the fluid volume of the blood" (Lauboeck, p. 70). It is therefore no more accurate to say a "central mechanism" drives the blood than to say "everything else does". All of which explains why a weakened heart results in greater pressure in the veins returning blood to the heart: the heart cannot cope with the volume of blood being driven to it. One of the key functions of the heart, according to the authors of this book, is momentarily to stop or damn up the flow of blood, bringing its motion into the kind of harmonious rhythm that seems so essential in all our bodily activity.
Of Warmth and Artificial Hearts
None of this is to belittle the heart's central importance in the body! Quite the opposite. It's just a matter of striving to grasp the complex realities of the matter -- realities that mechanical metaphors make invisible. To take an example not touched on above: the heart plays a significant role in regulating the body's warmth. Only about 20 percent of the oxygen it consumes is used for basal metabolism, and 5 to 20 percent is used for muscular contraction (beating):
How many of those who "know" that the heart is a pump also know that our hearts help to warm us?
Mechanical metaphors not only conceal many things from us; they also lead to dangerously unrealistic expectations. When Robert Tools, the first recipient of an AbioCor artificial heart, died on November 30, 2001, his doctors assured journalists that the experiment had not failed. As the Los Angeles Times reported, "Tools' doctors noted that the heart continued to beat flawlessly even as he died".
Yes, that's exactly what we want of a mechanism; anything else would indeed have been a mechanical failure. But this only shows how alien the mechanism remains in relation to the organism: it fails to become an organic expression of the body as a whole. As Holdrege notes (p. 20), the "flawless" beating in Robert Tools' chest testifies to the fact that the AbioCor heart was a mere mechanism, operating in grotesque disconnection from the dying person of whom it was intended to be an integral part. And there was nothing in the AbioCor's operation to make this disconnection a less fundamental reality for the living patient than for the dying one.
The AbioCor remains an engineering marvel, worthy of our admiration. But we will make the best use of such mechanisms only when we are less mesmerized by the engineering feat and more attuned to the organisms in which we try to deploy them.
A Concluding Note on Mechanism in Science
What does it mean for a science to be mechanistic? Clearly, different things to different people. At the simplest and crudest, we may equate a particular thing or process in the natural world with such-and-such a mechanism of our own making. Anyone who begins to assess this kind of equation, however, immediately realizes that, while the natural process and the mechanical activity may be alike in certain ways, they remain radically unlike in many other ways.
I suspect that few scientists, mechanistically inclined or otherwise, would insist upon the unqualified statement, "the heart is a pump" -- not, at least, when pressed with observations like those mentioned above. It is trivial to point out differences between the heart and any mechanical pump we have ever built or could foresee building. Yet many authorities continue speaking of the heart as a pump with little or no qualification. For example, Lauboeck cites a modern physiology textbook containing this statement:
If nothing else, this shows the powerful hold of mechanical metaphors upon the scientific community. But if we want to understand as sympathetically as possible what is really being said through such statements, perhaps we can put it this way: while the heart obviously is not a literal pump in the sense of being exactly like any mechanical pump we have ever built (after all, if this were the case, then the problem of supplying patients with artificial hearts would already have been solved), nevertheless, the kind of lawfulness governing pumps and various other mechanical devices is, without remainder, the kind of lawfulness governing the heart and explaining its activity.
This sounds more reasonable and is, I think, closer to what the proponents of mechanism in science usually have in mind. Yet it is an empty faith -- empty because the mechanical laws it invokes are adequate neither to govern nor to explain actual phenomena, whether organic or non-organic. Unfortunately, I can only gesture toward the issues here. (Before long I expect to announce a collection of working papers in which these issues are explored more fully.)
According to physicist David Bohm, mechanistic science is founded on the assumption that
This assumption has been greatly furthered during the scientific era by the fact that we are constantly surrounded by machines, which lend themselves (when considered in an extremely narrow fashion) to mechanistic analysis. But it has become steadily clearer that the essence of the machine -- the only aspect of it that perfectly embodies the assumption of the mechanists -- is what we call the "virtual machine": software.
The one fortunate thing about this development is that it has made clear a truth we have long managed to avoid recognizing: physical laws, understood as the precise mathematical and algorithmic formulations of the mechanist, neither determine nor adequately explain the world. To claim that they do explain the world is like saying software explains the machinery it happens to be running on. But since this machinery can assume infinitely many forms, utterly different from each other, what exactly is the software explaining?
There is a simple truth: the mathematical, logical, and algorithmic formalisms we abstract from machines, or from the world's phenomena, may really be there for the abstracting, but the abstractions are unable to explain the phenomena from which they were abstracted. This holds for every formalism. For example, we can abstract (at least approximately) the rules of a formal grammar from actual speech. But it would be just silly to say that the rules of grammar "explain" Shakespeare's Hamlet or Lincoln's Gettysburg address. The play and the address may "obey" grammatical rules, but this is not the same as being determined by them or explained by them.
Yet exactly this misconception underlies mechanistic science, as when it is said that Newton's laws of motion (understood as formal rules) explain the solar system -- or, worse, when complexity theorist John Holland says that these rules generate the complex motions of the solar system, as if the equations were themselves forces. Yes, Newton's laws (as approximations) are implicit in the solar system, just as grammatical regularities are implicit in our speech and an algorithm is implicit in all the computers that happen to be executing it. But all such regularities, understood in the mechanistic sense as precise and determining, tell us more about the formal necessities of mathematics, grammar, and algorithm than about the phenomena from which we abstract them. Certainly the algorithm running on a diverse set of computers "belongs" to the computers, but the necessities of the algorithm do not tell us about the distinct character of each real and embodied machine it is running on. No more do Newton's laws -- or any collection of such laws -- tell us about the diverse bodies that happen to be "obeying" them.
This problem, I'm convinced, afflicts every level of mechanistic explanation, all the way down to the minutest particles. There's a tendency to believe that the lower levels will somehow fill in the gaps of explanation at the higher levels. But the truth is that the resort to mathematical formalism -- and therefore the gap between clearly articulated syntactic rules, or laws, and real phenomena -- is even greater in particle physics than in other domains.
All this applies to sciences only insofar as they are mechanistic in spirit. Obviously, we gain a great deal of understanding from all sciences, but it comes from those largely unexamined ways in which we transcend mechanism. This needs elaborating, of course, and, as I mentioned, I hope soon to have the beginnings of a set of working papers available on the web for comment and criticism. The key point for now, however, is this: overcoming mechanism is not a matter of proving that, somehow, mechanistically conceived laws fail to apply at this or that "mystical" point. Rather, it's a matter of realizing that laws so conceived -- however valid they may be -- can neither determine the world nor give us an adequate understanding of it.
About the Book and How to Get It
The Dynamic Heart and Circulation consists of five chapters:
The book is now available from AWSNA Publications. The cost is $12 plus $5 for shipping and handling. To order, call 916-961-0927 or send a fax (with credit card information) to 916-961-0715. You can also send mail (with check or credit card information) to AWSNA Publications, 3911 Bannister Rd, Fair Oaks CA 95628. AWSNA has an online bookstore at www.awsna.org, where the book ought to be listed, but as of this writing it is not.
© 2003 Steve Talbott
Steve Talbott, author of The Future Does Not Compute: Transcending the Machines in Our Midst currently edits
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noncommercial purposes, with this notice attached.
Steve Talbott, author of The Future Does Not Compute: Transcending the Machines in Our Midst currently edits NetFuture, a freely distributed newsletter dealing with technology and human responsibility. NetFuture is published by The Nature Institute, 169 Route 21C, Ghent NY 12075 (tel: 518-672-0116; web: http://www.natureinstitute.org). You can reach Steve at email@example.com
This article was originally distributed as part of NetFuture: http://www.netfuture.org/. You may redistribute this article for noncommercial purposes, with this notice attached.