Chapter 4
The Nature of Physical Forms
The elusiveness of form
We see many different forms every day – trees, people, computers, written words, dogs – and we recognize them with no trouble at all. We take them for granted. But forms are surprisingly elusive when we try to think about them or pin them down. We can represent them in pictures and diagrams, photograph them, imagine them, see them in our dreams; but we cannot weigh them or capture them as readings on dials. They are not the same as energy, mass, momentum, electric charge, temperature or any of the other quantities of physics. Any particular thing we can directly see and experience has certain quantitative characteristics, but it somehow remains more than these: it also has a form, shape or structure. Consider a particular foxglove plant. It has a definite position, mass, energy and temperature; it is composed of a variety of chemicals in particular proportions; it has measurable electrical phenomena going on within it; it absorbs a certain percentage of the light falling on it; it transpires a certain amount of water per hour; and so on. But it is more than all these measurable quantities and rates; it remains irreducibly a foxglove.
As the plant grows, it incorporates into itself matter and energy taken from its surroundings; when it dies, the matter and energy are released, and the form of the plant breaks down and disappears. There is no change in the total amount of matter and energy as the foxglove comes into being and as it decays, but there is a change in the way in which the matter and energy are organized.
In the case of human artefacts, this elusive quality of form or organization is easier to think about. For example, as a house is built it takes up a particular structure. Its form is represented in advance in the architect’s diagrams, and to start with it originated in someone’s mind. But this form cannot be understood by weighing or chemically analysing the house, the plans or the architect’s brain. Nor can it be captured by demolishing the house and examining its constituent parts. With the same building materials and the same amount of labour, houses of different shape and structure could have been built. None of these houses could exist without the building materials and the energy expended by the builders; but neither the materials nor the amount of work fully explain the form of the house. So what is it? It exists materially in the house, but it is not itself material. It is a pattern, arrangement or structure of information that can be repeated more or less exactly in many individual houses, as in housing developments. It is more like an idea than a thing, but nevertheless it is essential to these actual houses and cannot be separated from them: it is not an abstract idea.
This is the paradox of all material forms. The form is in one sense united with matter, but the form aspect and the material aspect are separable. Every spoon, for example, has the form of a spoon, and this is what makes it a spoon. Spoons can be made of different materials, such as silver, steel, wood or plastic; and conversely the same matter that is in the spoons could be made into different forms, for instance into forks. Spoons come and go, but when they are broken, melted down or burnt, all the matter and energy in them persists: the existence or non-existence of spoons makes no difference to the total quantities of these fundamental physical realities.
For example, when a wooden spoon is burnt, the carbon atoms within it are incorporated into carbon dioxide molecules that are dispersed in the air. Let us think of the possible fate of one of these molecules. It may be absorbed by a nettle leaf, and the carbon atom may then be assimilated by photosynthesis into a sugar molecule, and thence through a series of biochemical transformations into a protein molecule within one of the leaf cells. This part of the leaf may be eaten and digested by a caterpillar of the peacock butterfly, and the carbon atom may end up in a DNA molecule in the butterfly’s body. The butterfly may be eaten and digested by a bird, and so on through endless food chains and carbon cycles.
The matter of any given carbon atom has the potential to be part of any one of countless millions of different forms, natural or artificial; it could also be in a diamond crystal or an aspirin molecule, a gene or a protein, a mushroom or a giraffe, a telephone or an aeroplane, an Australian or an Indian.
It is generally the case that the matter and energy of which things are composed have the potential to be part of many different forms; these forms cannot be fully explained just in terms of their material constituents and the energy within them. The form seems to be something over and above the material components that make it up, but at the same time it can be expressed only through the organization of matter and energy. So what is it?
Philosophies of form
Western philosophers have discussed the nature of form for well over 2,000 years. The same kinds of arguments have reappeared century after century and are still alive and well today. If we are to arrive at an evolutionary conception of form we need to pass beyond these traditional, non-evolutionary theories. But they still exert a deep and habitual influence on our thinking.
There are three main theories: Platonic, Aristotelian and nominalist. As we saw in Chapter 2, according to the Platonic philosophy, the forms of actual material things are reflections of eternal Forms or Ideas in the mind of God, or of transcendent mathematical laws: the source of the form is outside the material object, and indeed outside time and space. In the Aristotelian understanding, material forms are immanent in nature, rather than transcendent. The forms of organisms arise from non-material organizing principles inherent in the organisms themselves, their souls or psyches, to use the Greek word.
The nominalist tradition grew up in mediaeval Europe in reaction against both Platonism and Aristotelianism; and nominalists ever since have been like an opposition party to the ruling Aristotelians or Platonists. Nominalists keep reminding us that human words, categories, concepts and theories are all produced by human minds, but have a perpetual tendency to take on a life of their own, as if they exist outside our minds as well. We give things names (nomen, as in nominalism, is the Latin for ‘name’), which depend on human convention or convenience; but this does not mean that they refer to things that have an independent, objective existence. The things we characterize as horses, for instance, may indeed resemble each other; but if we say a horse form exists outside our minds as well as within them, we are making an unnecessary duplication. We are violating the principle of economy of thought. This principle is the famous Occam’s razor, invented by the fourteenth-century English nominalist William of Occam. By means of this mental razor, the Platonic Ideas and Aristotelian species-forms are cut away.
If all forms and concepts exist only in our own minds, we cannot know what is really out there in the world, underlying the phenomena of our experience: in fact, from a nominalist point of view we cannot know any objective reality that is independent of our minds and languages, because all knowledge depends on minds and languages.
This philosophical tradition has been especially strong in Britain, and in its positivist and empiricist forms continues to dominate academic philosophy in English-speaking countries. Within science, its main influence has come about through its long-established alliance with materialism, starting in the seventeenth century. Thomas Hobbes (1588–1679) as a nominalist rejected the idea that forms exist objectively outside our own minds, as both Platonists and Aristotelians thought they did. These philosophical concepts were just words: ‘Words are wise men’s counters, they do but reckon with them, but they are the money of fools.’1 On the other hand, as a materialist, Hobbes believed in the reality of material atoms in motion. The invisible entities of the other philosophies of nature were merely words and empty concepts; but the invisible atoms of materialism were real.
This alliance of nominalism and materialism leads to the familiar doctrine that concepts, names and ideas exist only in our minds, and at the same time our minds are aspects of the material processes in our bodies and are in principle ultimately explicable in terms of matter in motion. Thus the material processes in terms of which the mind is to be explained are more real than the mind that does the explaining. The matter is real in a way that the mind that conceives of it is not.
The combination of materialism and nominalism is inevitably paradoxical; there is always an internal tension, because at any time the nominalist critique can be brought to bear on the particles of matter themselves. These are also words and concepts in human minds, so why should they have any more reality or objective existence than any other categories or concepts? All that can be scientifically known of nature are observations and measurements. And even these are not independent facts; they depend on the conscious activity of observers and measurers, which in turn is guided by human interests, concepts and theories. Indeed, in the context of quantum mechanics, we have been reminded repeatedly that observations necessarily involve the minds of the observers; they cannot be regarded as objective facts independent of human activity and human minds.2
From here it is but a short step to solipsism or idealism: everything is in the mind. For the solipsist, everything is in his own mind; for the idealist, everything is in a universal or Absolute mind. And since human minds, especially the minds of physicists, find within themselves mathematical principles of order that have a curious, objective and timeless quality, this line of thought leads back to the familiar territory of Platonism.3
We now consider briefly the ways in which these traditional philosophies of form have shaped the contemporary scientific understanding of chemical and biological forms.
Platonic physics and chemistry
What is the nature of atomic, molecular and crystalline forms?
As we saw in Chapter 2, physics had been inspired again and again by the Platonic vision of an eternal, rational order that transcends the physical universe. And to a large extent, atomic, chemical and crystalline forms are still conceived of in a Platonic spirit.
First, the atoms of the elements, of which over 100 kinds are known, have characteristic and unalterable numbers. Hydrogen is atomic number 1, for example, sodium is 11, lead 82 and so on. When the symbols of the atoms are arranged in a series in accordance with their characteristic atomic numbers, they show a periodic pattern, with 2, 8, 8, 18, 18 and 32 elements in successive periods. This mathematical pattern is represented in the periodic system of the elements (Fig. 4.1). The atomic numbers are now understood in terms of the internal structures of the various kinds of atoms; they represent the numbers of protons in the atomic nucleus: lead, for example, has 82. The 82 positive charges of these protons are balanced by 82 negatively charged electrons, all of which continuously orbit the nucleus. It is precisely this number of protons that characterizes the lead atom – if it had 83 it would not be lead but bismuth; if it had 81 it would be thallium.
Figure 4.1 The Periodic System of the Elements, in the version of Niels Bohr. The atomic numbers correspond to the numbers of protons and electrons in each kind of atom. (After van Spronsen, Elsevier Science Publishers B. V., Biomedical Division, Amsterdam, 1969)
Atomic forms are currently explained in terms of quantum physics: the nature of the different kinds of atom is believed to be fully determined by quantum theoretical laws which in principle specify all the details of the structure of the nuclei and the orbitals of the electrons around them. In practice, the detailed calculations are too complex to carry out for any but the simplest of all atoms, hydrogen, with its single proton and electron. Nevertheless, it is taken for granted that if such calculations could be performed for all other atomic types, they would give the right answer and thus vindicate the adequacy of existing theories. But this is a matter of faith.
When the principles of atomic structure were worked out in the first few decades of the twentieth century, the universe was still believed to be eternal, and so were atoms and the laws that governed them. But atoms are now thought to have evolved over time. Once there were no lead atoms, or sodium atoms, or atoms of any kind at all. Insofar as atomic forms are still conceived of in a Platonic spirit, the periodic system of the elements already existed before the Big Bang; as the universe evolved, one by one the possible kinds of atomic form took on material existence. It is as if the eternal Forms of the atoms were awaiting their opportunities to be actualized in time and space.
The forms of molecules, like those of atoms, are usually conceived of as if they were Platonic Ideas. Chemists represent them symbolically as formulae. One kind, the rational formula, expresses the numerical ratios of atoms in a molecule; glucose, for example, is made up of 6 carbon, 12 hydrogen and 6 oxygen atoms: C6H12O6. But this rational formula is not unique to glucose; several other kinds of sugar molecule, such as fructose and mannose, have the same ratios of atoms, but they are arranged in different spatial patterns, which can be represented in structural formulae (Fig. 4.2), and more effectively in three-dimensional models.
It is conventionally taken for granted that the structures and properties of molecules have an eternal reality independent of the material existence of these compounds. Thus, for example, the orthodox assumption is that everything about a new kind of molecule could in principle be calculated in advance before the molecule was ever synthesized by research chemists for the first time; the structure and properties of the molecule are determined by transcendent principles of order that exist prior to its material existence.
Figure 4.2 Structural formulae of three kinds of sugar molecule. The lines represent chemical bonds. Carbon atoms are present wherever four lines meet, and hydrogen atoms where bonds end where no hydroxyl (OH or HO) group is indicated. Mannose and galactose differ from glucose in the position of one of their hydroxyl groups, shown with a box around it.
As we shall see in Chapter 7, it is not in fact possible to predict in any detail the structures and properties of molecules – for example the three-dimensional structure of proteins – on the basis of quantum mechanics and the other theories of present-day physics. It is an assumption that they are predetermined by timeless mathematical laws; and it is an even greater assumption that they are completely explicable in terms of the current theories of physics. Insofar as this assumption is still taken for granted, chemistry, biochemistry and molecular biology continue to operate within a Platonic paradigm.
Just as chemists study the forms and properties of molecules, crystallographers study the forms and properties of crystals. Each kind of crystal has a characteristic structure, and within the crystals the molecules and atoms are arranged in repetitive three-dimensional patterns, the smallest unit of which is called the ‘unit cell’ of the crystal.
The diagrams and models made by crystallographers (Fig. 4.3) are idealizations of the actual physical structure of the crystals. In the context of Platonism, they are more than man-made models. They are representations of the eternal archetypal form of the crystal, which is assumed to exist prior to the crystals themselves. As new kinds of crystals come into being for the first time, they are materializing or reifying archetypal patterns that are outside space and time.
Figure 4.3 A layer in a crystal of tetrazolate monohydrate, showing the repetitive arrangement of the tetrazolate and water molecules. (After Franke, 1966)
The conventional assumption is metaphysical. If, instead, we think of it as a scientific hypothesis, it makes empirically testable predictions. It predicts that, other things being equal, the crystals of a newly synthesized chemical compound should form in the same way, and at the same rate, the first time, the thousandth time or the billionth. This prediction seems to be refuted by the available facts. We return to this question in Chapter 7.
Platonic biology
In the eighteenth century, Carl Linnaeus constructed a great systematic framework for biology. His system of classification remains fundamental to biology today. He grouped together species within a hierarchy of taxonomic categories: genus, order, class, division and kingdom. At each higher level there were more basic similarities of form. For example the English oak Quercus robur belongs to the genus Quercus, which includes other oak species such as the evergreen holm-oak, Quercus ilex. This genus is in the family Fagaceae, which includes beeches and sweet chestnuts as well. This family is within the order Fagales, which also includes the walnut and birch families, in the class of dicotyledons, flowering plants with two cotyledons or seedling leaves in their embryos. Together with the monocotyledons (which include grasses, orchids and palms) they are part of the division Angiospermae, plants with flowers, and along with all other plants are part of the plant kingdom.
Linnaeus believed that he had been privileged to see the outline of the divine plan of creation, and that the rational Creator had formed plants and animals according to a meaningful order that man himself could recognize by means of his God-given reason.4
In the pre-Darwinian period, the comparative study of form, the science of morphology, revealed deep similarities between the body plans, skeletons and other structures of broad groups of organisms. The ‘rational morphologists’ of this period believed, like Linnaeus, that the biological realm is rationally intelligible and that in it are reflected eternal laws of form and organization. They developed the concept of the typical form or archetype of each group of organisms and saw the species in the group as variations on this archetypal theme. Structures that were variations of the same archetypal pattern were called homologous structures (Fig. 4.4).
Figure 4.4 Skeletons of the hand or forefoot of six mammalian species. All are modifications of an ancestral five-toed foot. (After Haeckel, 1910)
Richard Owen, for example, in his book On the Archetype and Homologies of the Vertebrate Skeleton (1848) described the form of the idealized vertebrate, an imaginary creature that represented the essence of the type, without the specialized details of any actual animal. Just as Goethe before him had tried to visualize the form of the archetypal plant, Owen wanted to discover a principle of unity within the type, a unity at a level of reality deeper than the material world. His understanding of homologies enabled him to think of evolutionary branching in terms of modifications of the same basic pattern; for example the archetypal five-fingered forelimb of vertebrates had been transformed into a whale’s flipper, a bat’s wing or a human hand. On the basis of the fossil record, he argued that the earliest members of any class were generally of unspecialized structure; the subsequent history of the class involved the development of specialized variations on this basic structural theme.
Owen did not believe that the evolution of forms was propelled by natural selection; rather, it was the unfolding of a rational plan through ‘causes’ or ‘laws’ that governed the appearance of new forms of life. Likewise, the great Swiss-American naturalist Louis Agassiz thought of the sequential development of living forms as the working out of variations on basic plans. Each basic type, and the ideal form of each specific variation on it, was fixed in accordance with the Creator’s will.5
Darwin and his followers rejected such ideas. They attempted to account for the archetypal forms and homologies historically, through descent from common ancestors. The Darwinian and neo-Darwinian interpretation of evolution through the interplay of chance and natural selection differs radically from a rational process of unfolding and transformation. There is no longer any attempt to understand evolution ‘from a higher and more rational standpoint’.6
But the spirit of the rational morphologists has never been completely displaced from biology. D’Arcy Thompson made a contribution to this tradition in his classic study On Growth and Form (1917). He shed much light on the form of organisms through both geometrical considerations and physical analogies (Fig. 4.5); and he showed that within broad groups, organisms could be understood as permutations or deformations of one another (Fig. 4.6). These transformations were orderly and appeared to be governed by mathematical laws. For example, in the case of the Foramanifera: ‘We can trace in the most complete and beautiful manner the passage of one form into another among these little shells.’ But, he added:
The question stares us in the face whether this be an ‘evolution’ which we have any right to correlate with historic time. The mathematician can trace one conic section into another, and ‘evolve’, for example, through innumerable graded ellipses, the circle from the straight line: which tracing of continuous steps is a true ‘evolution’ though time has no part therein … Such a conception of evolution is not easy for the modern biologist to grasp.7
Figure 4.5 D’Arcy Thompson’s comparisons of drops falling in fluid with the forms of jellyfish, (a) drops of ink falling in water, (b) a drop of fusel oil falling in paraffin, (c) Cordylophora, (d) Cladonema.(After D’Arcy Thompson, On Growth and Form; Cambridge University Press, 1942)
Figure 4.6 D’Arcy Thompson’s comparisons of fish species, showing how one can be ‘deformed’ into another. Top left, Scorpaena sp.; right, Antigonia capros; bottom left, the porcupine fish Diodora; right, the sunfish Orthagoriscus mola. (After D’Arcy Thompson, On Growth and Form; Cambridge University Press, 1942)
Brian Goodwin and Gerry Webster advocated an approach to biological form in this mathematical spirit in the 1980s.8 They hoped that a mathematical understanding of the generation of form in developing embryos would lead to a ‘knowledge of the world of natural forms and their relationships in terms of a theory of generative transformations’.9 They explicitly acknowledged that this approach recalls the spirit of the rational morphologists:
[It] attempts to shift the focus from a preoccupation with the contingent and the historical, which leaves biology without intelligible macroscopic structure, to concern with general principles of organization and transformation which could give biology a rational taxonomy and a theory of directed evolutionary change.10
Insofar as living organisms can be understood mathematically, the historical aspect of biology recedes into the background, as it does in physics and chemistry. Chemists do not usually ask themselves about the evolutionary origins of atoms and molecules; they generally take the Platonic paradigm for granted. A Platonic biology would resemble physics and chemistry in this respect, as Goodwin has made very clear. A rational taxonomy ‘would be quite independent of the actual historical sequence of appearance of species, genera, and phyla, just as the periodic table of the elements is independent of their historical appearance and is compatible with a great variety of possible sequences’.11
Aristotelian biology
The Aristotelian tradition lived on in biology in the form of vitalism. Whereas mechanists maintained that living organisms are inanimate machines, vitalists argued that they are truly alive. The inherent organizing principles of plants and animals, which Aristotle called souls, were referred to by a variety of terms such as vital factors, the nisus formativus (the formative impulse), or entelechy. Vitalists thought that these non-material vital factors organized the bodies and behaviour of living organisms in a holistic, purposive manner, drawing organisms towards a realization of their potential forms and ways of behaving, and that when organisms die, the vital factors disappear from them.
Although vitalism is rarely advocated nowadays in an explicit form, it continues to exert a strong, though often unconscious, influence on the thinking of biologists. In contemporary biology, theoretical entities such as genetic programs and ‘selfish genes’ play similar roles to vital factors, as we shall see in the next chapter.
The organismic philosophy of nature has much in common with the Aristotelian tradition (see above). It is more radical than vitalism in that it sees organisms at all levels of complexity, from subatomic particles to galaxies, and even the entire cosmos, as alive. The organizing roles that used to be attributed to souls and vital factors are now thought of in terms of systems properties, patterns of information, emergent organizing principles, or organizing fields.
The concept of morphic fields developed in this book represents an attempt to understand such organizing fields in an evolutionary spirit.
Materialistic biology
The orthodox approach to biological form is given by the mechanistic theory of life.
As we saw in Chapter 2, the mechanistic worldview grew out of a synthesis of the Platonic and the materialist philosophies of nature: on the one hand, all nature was governed by eternal, non-material laws; and on the other hand, at the basis of all physical reality were the permanent atoms of matter. An emphasis on the materialist aspect of this synthesis leads to a reductionist approach, the attempt to reduce more complex systems to less complex ones. From the atomistic point of view, the lower something is in the hierarchy of order, the more real it is; atomism emphasizes the supreme material reality of the smallest and most fundamental particles of matter.
In practice, there is no attempt in mechanistic biology to reduce the phenomena of life to the level of the fundamental particles of modern physics; reduction to the molecular level is generally considered sufficient. From molecules downward, reduction is assumed to be plain sailing; it is simply taken for granted that the structures and properties of molecules can be reduced to the properties of atoms and subatomic particles, and can in principle be understood in terms of the current theories of physics. This is the job of physicists and chemists.
Morphogenesis
So far we have been considering the main theoretical approaches to biological form. Platonists try to understand form in terms of transcendent archetypes or eternal mathematical laws, Aristotelians in terms of non-material organizing principles immanent in living organisms, and materialists in terms of the properties of molecules, and above all in terms of the chemical genes. In the next chapter, we turn to a discussion of the ways in which living forms come into being, and examine how these various theories fit the available facts. The coming into being of form is called morphogenesis, from the Greek words morphe, form, and genesis, coming into being.
Practically everyone agrees that an understanding of morphogenesis is essential for a deeper comprehension of the nature of life; and practically everyone also agrees that very little is currently understood about it. But one thing is clear: any satisfactory theory of morphogenesis has to take into account the fact that all biological forms have evolved. Morphogenesis is rooted in ancestral history.
The conventional explanation of the evolutionary basis of morphogenesis is, of course, in terms of the inheritance of chemical genes. The hypothesis of formative causation takes a broader view of heredity, and sees the inheritance of organic form – including the forms of molecules themselves – in terms of the inheritance of organizing fields that contain a kind of inbuilt memory. According to this point of view, living organisms, such as badgers, willow trees or earthworms inherit not only genes but also habits of development and behaviour from past members of their own species, and also from the long series of ancestral species from which their species has arisen.