and Man's Place in the Universe
Linda Simonetti Odhner
Before I state my thesis, I'd better clarify what idea I'm referring to with the word "recapitulation." Some of you are probably familiar with the phrase "Ontogeny Recapitulates Phylogeny." Ontogeny denotes the process of individual development: not merely the prenatal period but the entire lifespan, beginning with conception and proceeding through embryonic development, birth or hatching, infancy, metamorphosis in some cases, maturity, and old age, and ending in death. The embryonic and larval stages are usually emphasized because they represent the most dramatic changes.
Phylogeny refers to the sequence of ancestral forms in a creature's evolutionary history. It can also describe a branching family tree of hypothetical relationships between various organisms--called a "phy-logenetic tree."
Therefore ontogeny recapitulates phylogeny means that the sequence of stages in a creature's development repeats in brief--or recapitulates-- the sequence of adult stages in its ancestry. Take, for example, recapitulation in man (fig.1). From this figure you may gather that the application of this principle in real life is not all plain sailing. The facts leave room for great differences of opinion as to how true recapitulation is; it has a way of going in and out of fashion according to the intellectual climate of the times. In recent years recapitulation has undergone a revival of interest after about 70 years of contemptuous neglect.
Swedenborg's thought--including both his theological doctrines and his philosophy of science--offers an illuminating perspective on recapitulation. One doctrine in particular, which I'll call the doctrine of spiritual recapitulation, has special relevance to the concept of natural recapitulation. The more general doctrines of correspondence and of the human form create a context for the relationship between these two kinds of
Adapted from Hamilton et al., Human Embryology, figs. 91, 120, 123, 124, 125; Keeton,
Biological Science, fig. 22.56; Hickman, Integrated Principles of Zoology, fig. 29-19;
Ballard, Comparative Anatomy and Embryology, back endpaper; Moody, Introduction
to Evolution, figs. 4.9, 8.22.
recapitulation, and also shed light on its philosophical implications. Recapitulation, seen in the light of these spiritual principles, may be able to tell us something about our place in the universe, especially how we relate to other living forms on the earth.
Swedenborg's work may have played a significant part in the origin of recapitulation as a scientific principle. This origin took place when science was still in the process of differentiating from religion and philosophy and becoming an independent domain of knowledge. Swedenborg's philosophical works made a valuable contribution to this differentiation, and early recapitulation theories are a prime example of the need for it.
Before I plunge into particulars I'd like to say a few words about the relationship between science and religion. While some describe religion and science as overlapping domains, I regard them as complementary domains with an intimate relationship, but no real intersection. I don't believe we can derive philosophical or religious principles from scientific facts alone, nor can we derive scientific principles from the tenets of religion or philosophy. However, from a specific religious point of view we can work out the religious and philosophical implications of a scientific fact, and also elaborate and clarify our religious perspective. But we get out of science only what we bring to it.
In this presentation I want to contribute to a synthesis of religion and science that preserves their distinctness. Instead of deriving doctrine from science or science from doctrine, I see an analogical connection between them which emphasizes that they deal with different levels of knowledge.
In the following I will show how Swedenborg's doctrine of spiritual recapitulation bears on natural recapitulation. Next I present a history of the recapitulation concept and the different forms it took through the years, in terms of both philosophy and science, and how disagreements and refutations shaped it to fit the facts more closely. And finally I'll look at the role recapitulation and its alternatives play in human evolution.
Spiritual and Natural Recapitulation
In Swedenborg's final work, The True Christian Religion, Number 762 states: "In the Lord's sight the Church is seen as a single man, and this larger man must pass through his stages of life like an individual." This amounts to spiritual recapitulation--man in his spiritual life repeats the stages of spiritual development attained by his human ancestors. However, this is more complicated than it looks, for man's spiritual growth is not linear but cyclical: a series of descents into the natural, concrete things of life followed by ascents into spiritual things.1
In a sense the Most Ancient Church--the infancy of the human race--was the spiritual apex of human development, for its members loved the Lord above all, perceived spiritual things directly, and communicated openly with heaven.2 They occupy the highest heaven.3 The churches which followed this first one represented successively lower spiritual states. Yet this descent is necessary to bring about a new ascent and a new peak in man's history. How this would have been achieved without the perversion of the Fall, no one can answer with certainty.
The succession of states in an individual person's growth mirrors this spiritual descent in human history. Celestial angels surround an infant until his growing self-will tempers his total openness and innocence, when spiritual angels take their place.4 And so it goes; and many later cycles in his life will follow the same pattern.
In figure 2, I've placed the quotation concerning spiritual recapitulation in a context which shows how it might relate to natural recapitulation. The table shows four processes, two spiritual and two natural, two general and two individual. Three of these are are explicitly related to each other in Swedenborg's theological writings as human processes. The quotation on spiritual recapitulation links the two spiritual processes of individual regeneration and racial development. In addition, Swedenborg makes a strong connection between the natural process of human gestation and the spiritual process of human regeneration. Not only is there a "likeness and analogy," as stated, between the two, but an actual correspondence--a cause-and-effect relationship which prevails throughout the created universe. The complete correspondence between the human soul and body is just one instance of this universal connection between spirit and matter.5 Cycles of spiritual growth have their corres-pondential basis in natural cycles of growth and reproduction. Now, since individual regeneration has its own correspondence in human gestation, the universal law of correspondence implies a natural event which corresponds to the spiritual growth of the Grand Man, the form of heaven as a whole--in other words, a natural gestation process for the whole human species. That's where evolution comes in. I think of the descent by modification of those organisms leading to man as humanity's physical gestation. And so did those who supported the "biogenetic law" of the previous century--recapitulation.
While an adherence to Swedenborg's theological doctrines suggests some kind of parallel between ontogeny and phylogeny, this parallel could take some form other than recapitulation. Keep in mind that it cannot be a correspondence in the Swedenborgian sense, because correspondence operates only between different planes of creation--it's a vertical interaction--and both ontogeny and phylogeny take place on the physical plane.
I'm not going to tackle the evolution controversy in this paper. But it may interest you to know that you don't have to subscribe to the evolutionary point of view to accept recapitulation. And that leads me to the historical part of my presentation.
History of Recapitulation
I have three purposes in summarizing the history of recapitulation:
1. To arrive at a fuller understanding of recapitulation itself, and the attitudes that underlie its various forms, through a study of its development--its ontogeny, if you will.
2. To discover how various versions of recapitulation appear in terms of the Swedenborgian doctrines of spiritual recapitulation, correspondence, and the human form.
3. To determine Swedenborg's role--a small one, but not inconsiderable--in the history of recapitulation.
To help you keep your bearings in the ensuing horde of eminent figures in the history of science, I'm giving you a List of Important Characters in chronological order of birth (fig.3).
In all scientific and historical matters concerning recapitulation, my primary source is Stephen Jay Gould's excellent book, Ontogeny and Phylogeny. When I mention Gould I'm referring to this book.
The analogy between individual development and the progression from lower to higher animals has been around at least since Aristotle. The "Scala Naturae," or ladder of nature, is not an evolutionary progression, but a fixed and static one. All members of the animal kingdom are arranged on a single, linear staircase which ascends from the lowest species through the higher ones to its human apex. Aristotle compared this Scale of Being (as it is also called) with embryonic stages to confirm his assertion that development unfolds from an unorganized, undifferen-tiated beginning--the epigenetic view of embryology.6 Aristotle used this comparison only as an analogy--not as a scientific principle. To encounter a scientific version of recapitulation we must move forward over two thousand years to the end of the 18th century, shortly after Swedenborg's death.
Swedenborg and Naturphilosophie
The matrix in which the scientific principle of recapitulation emerged was a philosophical movement going by the German name of Naturphilosophie. In the interest of ready understanding I'll refer to those who created and followed this school of thought as Nature-philosophers. The basic ideas which formed Naturphilosophie closely resemble some of Swedenborg's philosophical and theological thought, and there is some evidence that he may have exercised an indirect influence on its formation. Most generally, of two opposing philosophical trends in the 18th century, Swedenborg followed the one which led to Naturphilosophie. I quote from Erik Nordenskjold's History of Biology:
Parallel with the [materialistic] philosophy of the enlightenment... there developed another, entirely contrasted, conception of nature, ... which, possessing in Stahl, Swedenborg, and Caspar Friedrich Wolff its scientifically most important representatives, appears throughout the eighteenth century in various forms; a view of life which sees in natural phenomena an expression for the operations of spiritual powers, whereas, according to its tenets, the mechanical explanation of nature admits of only a superficial observation of what takes place, without any insight into that inherent connexion in existence which the spiritual powers imply.7
More specifically, Goethe was an individual who absorbed Swedenborg's work and, in turn, profoundly influenced Naturphilosophie. He believed that all natural science was based on comparison, and that an "ideal type" (shades of Plato?) existed with which all animal forms could be compared. Rejecting materialism, he regarded the spiritual element as essential in understanding science.8
Some of the ideas of Lorenz Oken, one of Naturphilosophie's most important representatives, are described by Nordenskjold in these terms:
We find in [Oken's ideas] a great deal of ancient mysticism, such as the mysticism of numbers--recurring groups of three and four-- the comparing of the animal kingdom to a great body, reminiscent of Swedenborg's speculations... .9
Now all this may be interesting, but it's pretty flimsy evidence; and keep in mind that this is not a definitive study, because in no case did I consult the original source in question. In any case, I believe that the connection between Swedenborg's theological doctrines and the idea of recapitulation is more significant than the degree of actual influence involved. Regardless of the influence question, striking similarities exist between Swedenborg's work and Naturphilosophie.
Gould summarizes the basic beliefs of Naturphilosophie as follows:
"1. An uncompromising developmentalism." Not any one form, but the movement from initial chaos to final order in man, from lower to higher, is the "irreducible property of nature."10 Gould emphasizes that this does not require a belief in evolution; physical continuity is not necessary where spiritual continuity is present.
"2. A belief in the unity of nature and its laws. Man is the highest configuration of matter on earth, but we are indissolubly linked to all objects as the goal toward which they strive."11 These statements, the last one in particular, strongly recall Swedenborg's, "Everything in nature has relation to the human form,"12 and also, "The uses of all created things ascend by degrees from ultimates to man, and through man to God the Creator from whom all things are."13
Now, the form which recapitulation originally took depended not only on its philosophical milieu, but also on two other things: the state of embryology at the time, and the perception of how different forms of life could be organized to create a meaningful pattern. I'll start with embryology, and Swedenborg fits in here too.
Swedenborg and Embryology
Deep thinkers on the subject of embryology--and Swedenborg is no exception--tended to avoid the extreme forms of both epigeneticism and preformationism. Most preformationists didn't really believe that a tiny, fully formed homunculus sat curled up in every human sperm head. Most epigeneticists didn't believe that the fertilized egg was a completely unorganized mass whose development was directed solely from without--or above. Those who favored epigenesis pointed to the visible evidence of gradual formation from apparent initial chaos. Those who espoused preformation pointed to the equally visible evidence of developmental consistency, and concluded that the egg had to contain the essence of what it would become. Both positions were equally valid.14 At the time Naturphilosophie began to flourish, the pendulum was swinging toward an emphasis on epigenesis.
Swedenborg was fascinated by embryology and studied others' observations on the subject. He believed in the soul as a spiritual entity directing natural development, and inferred the soul's mode of operation from scientific observation. He noted that in the egg there was "no type of the future body,"15 and concluded that there must be a spiritual "formative substance or force"16 guiding development, and what's more, that the egg reflects this force in an order that is invisible yet physically present: "for what before appeared to the eye a blank undigested mass, is now seen to involve the most perfect order and accurate discrimination."17 With these words Swedenborg encompassed both sides of the argument. He did not treat the postulation of spiritual forces as a scientific copout; he wasn't letting us off the hook in terms of scientific observation and explanation.
The Animal Kingdom
Now we turn to the puzzle of variety in animal forms. The domination in men's minds of that ancient linear hierarchy, the Scale of Being, began to weaken as they came to terms with the staggering diversity among different forms of life. It was getting harder to make everybody stay in line. The branched model of animal classification began to take over under the influence of Linnaeus and Cuvier. The Nature-philosophers stuck with the Scale of Being, and considered the philosophical significance (usually in recapitulatory terms) of animal traits. But Cuvier rejected both Naturphilosophie and the Scale of Being, seeing the significance of anatomical facts purely in terms of function. A Nature-philosopher would see a clam as symbolizing a stage of human development; Cuvier would assert that clams have absolutely nothing to do with human development, since they belong to a different branch of the animal kingdom.18 The evolutionary question naturally follows here, but I'll postpone it until after I've described the Nature-philosophical brand of recapitulation, which got along nicely without the benefit of evolution for many years. After that we can see how evolution fitted in.
The Meckel-Serres Law
The Nature-philosophers were always making analogies--it was their favorite pastime--and attaching great significance to them. This grew naturally out of their basic principle: "The laws of nature operate in the same way upon all processes and all objects."19 Any similarity seen or imagined between different phenomena might become the basis for a new law affirming nature's unity. Recapitulation was actually one of the most sensible and factually based of these many parallels. In Naturphilosophie, recapitulation fits into a larger scheme funneling the whole of nature into the linear Scale of Being; beginning with various minerals and progressing through plants and animals, "the form of organization ascend[s]," culminating "in the form of a man."20
Leading Nature-philosopher Lorenz Oken endorsed recapitulation wholeheartedly. He saw it in relatively crude terms as the simple addition of organs and powers. Only man has the full complement of organs; all other animals lack one or more. If "the stages of human ontogeny... represent the completed forms of lower organisms," then, as Gould paraphrases Oken, "what are the lower animals but a series of human abortions?"21 And quoting Oken directly, "The animal kingdom is only a dismemberment of the highest animal, i.e. of man."22 Seeing the animal kingdom in these terms may be revolting, but it does follow logically from Oken's prior assumptions.
Nature-philosophical allegiance to the relentlessly linear Scale of Being is another aspect of the same tendency to do symbolic violence to nature. In Oken's scheme, polyps, clams, and snails rub shoulders (so to speak) with worms, flies and fish in flagrant disregard of their great differences. This constriction of the branching tree of animal diversity into a telephone pole of "human dismemberments" illustrates the way the Naturephilosophers throttled nature into what they judged was the proper shape to demonstrate man's supremacy in nature.
This system led to great absurdities when applied to human development. If a "clam stage" in the human embryo sounds silly, the idea that the human newborn represents a "bird stage," due to a lack of teeth, doesn't improve matters. (Gould cautions us, "It is important to understand what Oken means by these statements, lest he be dismissed as a madman.")23 The connection is not one of actual identity or even appearance; the embryo merely passes through stages symbolized by these various creatures, as it adds the organs which represent the essential nature of each. This sort of thing lifts recapitulation right out of the realm of science.
Naturphilosophie and recapitulation are both fascinating and useful to contemplate. It's just this particular combination of the two that irritates me. I'm being hard on Oken, scorning his version of recapitulation as the most disgusting ever to come down the pike, but I'm doing it for the purpose of contrast.
The Nature-philosophical principle that all animals can be viewed as stages in a progression leading to man superficially resembles Swedenborg's doctrine that all living creatures are animated by a striving toward the human form.24 The essential difference between the two ideas rests, I believe, in the definition of "human." When comparing the human form with animal forms, the Nature-philosophers naturally saw it in physical terms. But this inevitably led to seeing the animal kingdom as (to use still another metaphor of the time) "Man disintegrated."25
But according to Swedenborg's doctrine of the human form, our humanity does not consist in our upright posture, our fingers or toes, our warm blood, our way of reproducing, our facial features, or even our large brains--none of which are outstandingly unique in the animal kingdom. None of these things in themselves makes us human; they only make our humanity possible. The human form, according to Sweden-borg, consists simply in love and wisdom united in use.26 We human beings reflect this form in our twin faculties of liberty and rationality-- that is, free will and the ability to see what is true. These two capacities together enable us to make wise choices and carry them out in our lives, and that is what makes us uniquely human. The human form--love and wisdom united in use--is universally present in creation. Most created things express this unconsciously, but they all express it completely, in different forms and in varying scales. This way of looking at the human form enables us to see whole--not mutilated--images of it in all aspects of creation. We can avoid the absurdity and the arrogance of thinking that other creatures would be better if they were more like us, when they really perform their own uses most perfectly as they are.
Keeping all this in mind, we can return to our history of recapitulation. Johann Meckel's version of it was a refinement of and improvement on Oken's. Meckel is considered the foremost spokesman for the Nature-philosophical version of recapitulation, which in this century acquired the name "Meckel-Serres Law" to distinguish it from Haeckel's later and more famous "biogenetic law."27
Instead of seeing nature's developmental tendency in terms of the simple addition of organs and powers, Meckel thought in terms of "coordination and specialization; simple animals have many similar but poorly coordinated parts; advanced creatures have highly distinct and specialized organs that function together in an integrated body."28 Biological progress takes the form of "the reduction of many identical parts to fewer, more specialized, and more coordinated organs."29 This view of life's ascent can reflect Swedenborg's assertion that "a one formed of many is never constituted of single things which are... exactly alike; but of various things harmoniously conjoined."30
The other man for whom the Meckel-Serres Law was named, Etienne Serres, belonged to the French transcendental morphologists, who shared most of their basic assumptions with Naturphilosophie. The transcendentalists believed in the Scale of Being and a single structural plan to which the whole animal kingdom conformed. Serres admitted the great diversity in adult forms as pointed out by Cuvier, but countered this objection by pointing out the great similarities between vertebrate embryos and invertebrate adults--that is, by invoking recapitulation.31
The most important thing to stress about the Meckel-Serres Law, especially in contrast with the biogenetic law, is that it invokes no direct causal connection on the physical plane between the ascents of embryonic stages and adult forms. The parallel between the two arises solely from their common origin in the spiritual law of universal striving toward man, which finds a congruent expression in both processes. Figure 4 shows the structure of the Meckel-Serres Law: individual development is continuous, the Scale of Being discrete, and their connection only on the spiritual level.
Now we come to a man who achieved an unusual feat--he followed Naturphilosophie but didn't accept recapitulation. This man was the embryologist Karl Ernst von Baer, who may have done more for recapitulation by his refutation of it than its most ardent champions by their support. He saw all development unified by a single tendency, as the recapitulationists did, but in his view all organisms tended toward increasing differentiation from each other. In his words, "The development of the individual is the history of growing individuality in every respect."32 His opinion that there are several basic types of animal agrees with Cuvier's interpretation of comparative anatomy, and he maintains that these various types have no developmental stages in common with each other. He emphasizes, "The vertebrate embryo is, at the beginning, already a vertebrate; at no time is it identical with an invertebrate animal," and goes on to say, "... in their development, the embryos of vertebrates pass through no [known] adult stage of another animal."33 Thus, animals of the same type resemble each other more as embryos than as adults; but this is not recapitulation. Von Baer asserts that development follows a diverging pattern, while recapitulation is a linear phenomenon.
Now, several of the points which von Baer brings up in his critique of recapitulation might be considered to be merely matters of differing emphasis. After all, Oken and Meckel never claimed that any vertebrate embryo is identical with any invertebrate adult. The issue of divergent development is more of a problem; recapitulation requires that changes in ontogeny be tacked onto the end of an existing pattern of development, while von Baer asserts that the more two adult animals differ, the earlier their respective ontogenies will diverge from each other.34 And Von Baer's rejection of the Scale of Being is unequivocal. It is impossible to fit all the members of the animal kingdom into a single hierarchy. Since the Meckel-Serres Law was based on the Scale of Being it could not be reconciled with von Baer's laws.
But evolution transformed recapitulation to an amazing extent, and one result was to make recapitulation much more difficult to distinguish from von Baer's point of view. Let's look at how evolution came to be integrated with recapitulation.
The Biogenetic Law
Considering how long evolution and recapitulation were moving in the same intellectual circles, they were a long time finding each other. In his book Darwin's Century, Loren Eisely makes the point that, although evolution was "in the air" in the 18th century, it took a long time to enter the mainstream of biological thought, because in the process it had to displace the belief in special creation and the fixity of species which followed from a literal interpretation of the Bible.35 It is worth noting that Swedenborg escaped this bondage to the literal sense of the Bible. His scheme of each species of animal arising from a species of plant, in The Worship and Love of God, while not evolutionary in the modern sense, was a definite step away from special creation.36
Eisely also draws our attention to one of the reasons why evolution began to make headway when it did: the epigenetic view of development. As he puts it, "... to accept development, an emergence by degrees, in the case of the single individual makes it possible to accept with greater equanimity the conception that a species itself may have come into existence by some more extended process of phylogenetic change."37 Attitudes toward the two processes of ontogeny and Phylogeny affected each other because of the analogy that naturally crops up between them.
Lamarck's version of evolution (as far as I can find out) was never linked with recapitulation, though it bore the marks of a Nature-philosophical slant, and in fact incorporated the Scale of Being in its structure. Why didn't the recapitulationists seize on it eagerly? Perhaps Naturphilosophie simply wasn't ready for evolution. It wasn't until after the publication of Darwin's On the Origin of Species that evolution was finally married to recapitulation and gave it a new form. The man whose name is associated more than any other with the new, evolutionary version of recapitulation was Ernst Haeckel. Although, as Gould points out, many people "rediscovered" recapitulation after Darwin, Haeckel was the most conspicuous.38 He considered it the unifying principle of biology, calling it the "biogenetic law." He coined the words "ontogeny" and "phylogeny" (among many others), and originated the phrase "ontogeny recapitulates phylogeny." It is his formulation of recapitulation that I outlined at the beginning of this paper.
Evolution freed recapitulation from its uncomfortable fusion with the now-outdated Scale of Being. It applied only to directly ancestral forms on a branching family tree (fig. 5), and as a result, embryology became a source of information about evolutionary lineages which supplemented the fossil record.
The biogenetic law was much more of a scientific principle than the Meckel-Serres Law could ever be, for it required a direct causal link between ontogeny and phylogeny. Haeckel said, "Phylogeny is the mechanical cause of ontogeny," and as far as I can see, you could just as well say it the other way around; for while any current ontogeny is caused by the phylogenetic series which leads up to it, each new form in that phylogenetic series arises from a new increment in ontogeny. It puts me in mind of the chicken-or-the-egg dilemma. In any case, it brings up a question that can no longer be ignored: How are ontogeny and Phylogeny causally related? To put it another way, how is hereditary information passed on? Although speculation was rife, nobody really knew; so recapitulation could not be proved or disproved on the basis of the laws of inheritance. Instead, hereditary laws were deduced from the presumed fact of recapitulation.39
Now let's get back to von Baer's laws. According to the biogenetic law, recapitulation follows the branching pattern of evolutionary lineages. In this case, any two species living at the same time, since they display a fraternal rather than ancestral relationship, would show divergent development. Their divergent phylogeny would be reflected in divergent ontogeny. This result follows both from the biogenetic law and von Baer's laws. Only when one form is directly ancestral to another are the two points of view incompatible--recapitulation would predict identical ontogeny until the end, while von Baer's laws would predict an earlier divergence. However, it is usually impossible to make a direct comparison between the ontogeny of an ancestral form and its evolutionary descendant.
We can search for ancestral forms in the fossil record, of course. We may come up with a nice string of fossil horses or hominids, and assume they represent a single, direct line of descent. However, every new bit of knowledge we acquire makes the phylogenetic picture more complex. According to the Scale of Being, the organization of the animal kingdom looks like this (fig. 6a): a straight line. According to Cuvier and von Baer, it's a tree with four major branches, and Darwin followed this basic scheme in his theory of evolution (fig. 6b). As more forms of life come to light and the scheme of classification becomes more detailed, the tree acquires more branches and twigs; and these days, to give an accurate idea of the involved intricacy of even a fraction of all the lines of descent would require a picture like this (fig. 7): a dense and tangled bush bristling with little offshoots everywhere. Current theory predicts that the majority of species, both living and extinct, never give rise to major evolutionary lines. Therefore, given a series of fossil animals, even closely related ones, the odds are against their being in a direct line of descent. Thus it may be even harder in practice than in theory to distinguish between von Baer's laws and recapitulation.
In fact, there is a considerable difference of opinion as to just how much difference there is between them. It strikes me that the two points of view are only mutually exclusive if they are generalized as universal principles--there's an area of possible overlap between them. Gould is absolutely adamant in his opinion that they are fundamentally incompatible, and have been confused far too much over the years;40 Ernst Mayr, in his recent book The Growth of Biological Thought, asserts exactly the opposite--that too much has been made of their differences and they're not really as different as people think.41 Going for a third opinion to Nordenskjold, we find that he supports the idea of a clear-cut distinction between recapitulation and von Baer.42 I don't have a definitive answer to this problem--frankly, it has me stumped for the moment.
The facts of embryology are numerous and complex, and how you see them depends on your point of view. Glaring exceptions exist to both von Baer's laws and Haeckel's biogenetic law, although both viewpoints find striking support in individual cases. Haeckel had to allow for scores of exceptions to his law. One concession to facts which strengthened the biogenetic law was the realization that an organism didn't recapitulate its ancestors as a whole nearly as faithfully as in its individual organs and systems. The timing in development of any component was often dissociated from the others.43
I often think it would be nice if Haeckel had been right. The idea is so elegant and so evocative of Swedenborgian doctrine--a gestation process for the human race having an exact parallel with individual human development. But despite all the examples supporting recapitulation, and despite the exceptions the biogenetic law generously allowed for, recapitulation as a universal principle couldn't stand up in the face of genuine knowledge about how heredity works. As it grew clear that heredity consists of discrete, coded instructions with their own hierarchy of operation--some genes regulating the rates at which others governed various processes--the idea that only the end of ontogeny could be affected by genetic mutations became untenable.44 Any stage in ontogeny was fair game for the effect of mutations. And any change occurring early in ontogeny was likely to affect all subsequent stages as well. Thus, von Baer's laws survived the emergence of a true science of genetics better than Haeckel's law of universal recapitulation did. Recapitulation was reduced to just one of several modes of evolution.45 And yet to those who supported recapitulation it still seemed a fairly pervasive phenomenon.
To shed some light on why recapitulation may appear more widespread than it actually is, I turn to von Baer. I present this lengthy quotation in full as cited by Gould, not only because it's delightful, but also because it illustrates some important points about how we see the human form in its natural context. In his critique of recapitulation, von Baer says:
Let us only imagine that birds had studied their own development and that it was they in turn who investigated the structure of the adult mammal and of man. Wouldn't their physiological textbooks teach the following? "Those four-and two-legged animals bear many resemblances to embryos, for their cranial bones are separated, and they have no beak, just as we do in the first five or six days of incubation; their extremities are all very much alike, as ours are for about the same period; there is not a single true feather on their body, rather only thin feather-shafts, so that we, as fledglings in the nest, are more advanced than they shall ever be.... And these mammals that cannot find their own food for such a long time after birth, that can never rise freely from the earth, want to consider themselves more highly organized than we?"46
First of all, by putting himself in a bird's place, von Baer is seeing the human form in creation in a far more broadening and universal way than the strait-laced Scale of Being allows--or even, and I say this with some regret, than the biogenetic law allows. He is not measuring the rest of nature by man and finding it wanting. Instead he discovers how essential human traits, which transcend physical form, might be expressed in birds. Birds who write biology textbooks must be human, right? In this context he brings up important points about our own perspective.
First, in judging the relative degree of advancement of various animal forms, we tend to think in terms of our own particular specializations, naturally considering them the most important and significant. Other creatures are inevitably less advanced in the specializations we specialize in, so in a way, recapitulation is in the eye of the beholder.
A related point is that we see the differences between ourselves and our near relatives more clearly than the differences among more remote members of the animal kingdom. That is, we're more aware of, and more familiar with, the details of our own neck of the taxonomic woods, with the result that we find more significance in them too. This bias may prevent us from appreciating the full diversity of life, as happened with those who lumped most invertebrate species into a category called "worms" and then forgot about them.47 Cuvier, who thought these "worms" merited a second look and considerably more sorting out, avoided the "human" bias by beginning his studies of comparative anatomy with marine animals such as fish, molluscs and crustaceans.48
A full appreciation of the diversity of earthly life forms may sharpen our awareness of the far greater variety of human affections among men. No two people are exactly alike, and their different loves make up a harmonious whole in heaven, for all of heaven takes the form of a single man, as Swedenborg tells us.49
In a similar way the uses of different animals and plants combine to form food webs and whole ecosystems in wonderful ways. The Scale of Being is obviously a simplistic way of viewing these intricate interactions, and so, less obviously, is the biogenetic law--still too neat and tidy, still with too much emphasis on hierarchy. I would hate to have to give it up completely, but I might loosen my hold on it if I could find something equally suggestive of spiritual principles to take its place.
If recapitulation is merely one mode of evolution among several, as Gould asserts,50 then its opposite--paedomorphosis--should occur frequently too. Paedomorphosis is the appearance of juvenile features in the adult, which implies that the previous adult features are lopped off the end of ontogeny into oblivion. It results from retardation of development relative to the timing of maturity. In the days when the biogenetic law held sway, paedomorphosis was dismissed as a degenerate exception to the prevailing drive toward recapitulation. But in this century paedomorphosis began to be recognized as an important mechanism of evolution, just as creative, in some cases, as recapitulation. Paedomorphosis possesses special interest as a significant factor in human evolution.
Recapitulation and Paedomorphosis in Human Evolution
Let's start with some examples of recapitulation in human evolution, and then we'll get to paedomorphosis. I doubt that any similarities between ontogeny and phylogeny stand unchallenged as examples of "real" recapitulation. Nevertheless, some of the parallels, especially those
from Moody, op. tit., fig. 4.16; Ballard, op. tit., figs. 25-5,25-7,25-11;
Hamilton et al, op. tit., figs. 159, 168.
which involve single organs and systems, are striking. The mammalian heart recalls its vertebrate ancestors with respect to its division into right and left halves (fig. 8).
The hearts of fish, amphibians, reptiles, and mammals show progressively more complete septation as their double circulations grow more efficient; the human heart follows this sequence, and while it is essentially complete early in development, the last hole closes only after birth, when air-breathing begins.
The human embryo shows other traits which hint at its origins, among them a tail and a notochord which later disappear, and eyes which begin on the sides of its head before converging toward the front. The human brain, like the heart, recalls the vertebrate sequence of increasing size and relative importance of the cerebral hemispheres (fig. 9). It begins as a simple tube which then folds and buckles, and the forebrain gradually grows over the rest of the tube to become the cerebrum. In this respect the brain does exhibit recapitulation. But it achieves its large size by means of a retardation in the timing of growth rates. Primate brains are characterized by an initially steep growth curve, which levels off at about the time of birth. Human brains follow a curve of about the same shape, but the leveling off occurs much later, at about two years of age, which results in a large size in both absolute and relative terms.51 Since a large brain relative to body size is a juvenile characteristic in primates--in fact, in mammals generally--man's relative largeness of brain is a paedomorphic trait. The human brain achieves the interesting feat of being recapitulatory and paedomorphic at the same time.
It may be possible to make the following generalization: those traits in man which show recapitulation do so with respect to other vertebrate classes, while his paedomorphic traits refer to mammal and primate characteristics. In other words, the general paedomorphic trend is a relatively late phenomenon in human evolution. This is probably an oversimplification, as many generatlizations are, but possibly useful nonetheless.
Man's relatively large head and brain may be his most striking and significant paedomorphic feature, but we can add others to the list, all more or less related in terms of form and function. Man's flat face which lacks a projecting muzzle, his small, late-erupting teeth in a small jaw, his lack of a cranial ridge for attachment of the massive jaw muscles which he also lacks, are all paedomorphic traits, and we're not even down to the
neck yet. The attachment of tdenborg and She spine directly under the skull, instead of at the back, allowing for man's upright posture, is also paedomorphic-- and at the other end, his unrotated, unopposable big toe, which makes walking easier.52 The list could go on.
All these things play a part in making man what he is in their own right, but they also form part of a larger, more comprehensive picture of a general slowing of the biological clock. An extended childhood forms part of an extended life span in which many childish traits are never lost.53 From a Swedenborgian point of view, this has spiritual implications. Man is designed by the Lord not only for a long life in this world, but also for an eternal life in heaven--a life in which he can continue to make free choices. Although each choice he makes in life eliminates certain options, his life is never as circumscribed as that of an adult animal; he needs to preserve the flexibility, the adaptability, the potential for change, and the capacity for learning, of childhood.
Human paedomorphosis gains an added significance in relation to human recapitulation. I suggested above that paedomorphosis followed recapitulation in human evolution. If this is true it can remind us that human growth returns to its origin over and over again. Descent into uses and ascent into loves follow each other without end. As a child grows up and increases in mastery of this world, his spiritual state descends. Paedomorphosis in human evolution may illustrate the necessary return to innocence in human regeneration. Since it involves a reduction in physical strength and a childish appearance, human paedomorphosis may look like a backward step in evolution, but it's really a step forward--just as attaining the innocence of wisdom is a step forward in spiritual growth. In both cases the traits which appear youthful on the surface veil a deeper maturity of development.
This view of matters may represent just as severe a distortion of science as a slavish allegiance to recapitulation. But perhaps it too is a step forward, just as the biogenetic law was an advance from the Meckel-Serres Law and the Scale of Being. A preconceived idea of how the facts of science should support our philosophical point of view can lead to a distortion of those facts; but coming to terms with the ways they frustrate our expectations might bring us new depth of understanding and insight in all areas of thought. It is not only the history of science which suggests this conclusion; the same message emerges both from Swedenborg's theological doctrines and from his example as a scientific philosopher.
53 Gould, op. cit., pp. 400-404.
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