Evolution Evolving

Craig Holdrege

From In Context #21 (Spring, 2009)

This essay is based in part on the first of four talks on evolution that Craig gave at The Nature Institute in the spring of 2007. It was meant as one entryway into the topic of evolution, which was explored in greater depth and breadth in the ensuing three talks.

Without a doubt, Charles Darwin (1809-1882) is the most influential evolutionary scientist. In 2009, the world celebrates a Darwin year: 200 years ago Charles Darwin was born and 150 years ago, in 1859, he published his Origin of Species. This book — the first edition sold out in one day — changed forever the landscape of thinking about life, its history, and its diversity.

While Darwin was by no means the first person to write about evolution, no book has had such a great impact on a whole way of interpreting biological phenomena. Darwin was careful and thorough. He mulled over his ideas and refined them for more than two decades before Origin of Species was published. In Origin, he builds a carefully crafted argument supported by a wide array of evidence. For Darwin, evolution was a natural consequence of a relatively small number of fundamental biological processes.

You know that someone has struck a deep chord when his ideas not only find a legion of supporters, but also a legion of vehement antagonists. And the debates about evolution and explanations of evolution have never ceased — just think of the contemporary controversy concerning creationism and intelligent design.

What I want to do in this essay is to show how thinking about evolution itself evolved over the course of the last few centuries, and then describe Darwin's view of evolution. For those of us who live in an age in which evolutionary thought is part of our culture, one of the most intriguing facts is that many phenomena we so easily interpret as indicating evolution were not seen that way in earlier times.

What are Fossils?

You may think that the idea of organisms evolving jumped out at people when they started to look carefully at the different kinds of fossils one finds in the successive layers of rock in the geological record. Ammonites, for example, were widespread in older rock layers but are not present in more recent layers. This would lead us to the idea that ammonites existed — as relatives of the more recent chambered nautilus (and more distantly, squids) — in oceans of ancient times and then died out. Other organisms evolved out of the ammonite-like creatures and eventually became today's nautilus.

But take a man named Robert Plot, who in 1676 wrote a book on the Natural History of Oxfordshire. He describes “stones in the form of shell-fish” that, he speculated, had been “naturally produced by some extraordinary plastic virtue latent in the earth or quarries where they are found” (cited in Edwards 1967, p. 5). He thought that ammonites were formed “by two salts shooting different ways, which by thwarting one another make a helical figure.” Around the same time another naturalist wrote about a different kind of fossil, “surely in these the disports of nature are very remarkable, and to me it seems very evident, they are but the very contextures of salts, sulphurs, earths, and not the exuviae of creatures” (cited in Edwards 1967, p. 6).

When you look into the history of paleontology you find many such examples of naturalists interpreting fossils as earth creations and not as the remains of single living organisms. They were looking at the “same” things we see, but saw something different. They were not crazy; they were just looking with different mental eyes. It is almost impossible for us today to take such a way of looking seriously. But we can at least become aware of the fact that it has not always been self-evident to serious students of nature that a fossil represents the remains of a once-alive creature. I think you would be hard pressed to find anyone today who, when viewing an ammonite, wouldn't conclude that it is the remains, impression, or fossilized form of some animal. This is our “natural” way of thinking, a way of thinking that was quite "unnatural" before the late eighteenth and early nineteenth century.

Great Chain of Being

In 1677, Sir William Petty wrote,

We farther consider, that there be a Scale of Beings, which reaches from the first Cause to the most imperceptible Effect, from the infinite Creator to the smallest of his Productions, we have reason to believe, that as we can see an innumerable Company of Beings below us, and each Species to be less perfect in its Kind, till they end in a Point, an indivisible Solid: so there are also an infinite Number of Beings above us, who as much exceed us, as we do the minutest Insect, or the smallest Plant . . . (Cited in Lovejoy 1976, pp. 190-1)

This is a formulation of the idea of a great chain of being, which was pervasive in Western thought from the Greeks, through the Middle Ages up into the 1700s and 1800s (Lovejoy 1976). This is the view that there is a spiritual order to things and that every creature has its place in the universe — a kind of spiritual ladder, leading from amebas to worms, insects, fishes, reptiles, birds, mammals, human beings, and then continuing upward to the angels, the archangels and the other angelic hierarchies. This chain or ladder of being was clearly hierarchical. But it was not temporal. It was not about development. It was about the plenitude of God's creation evident on all levels.

For hundreds and hundreds of years people saw this chain of being, felt this chain of being, and it was not a temporal chain of being. God's wisdom was spread out into the created world. This is a world view so different from our present-day world view that it is hard to imagine. But it is important to try to strip away our own predilections — as Owen Barfield urges in his book Saving the Appearances (1988) — so that we can begin to take the past seriously rather than just passing judgment from the high altar of the present on the “inferior” or “childish” views of the past. If this succeeds to some degree, a whole new way of looking opens up, namely, we begin to see that consciousness itself evolves and that one important phase in this evolution is the emergence of the idea of evolution itself.

Thinking Evolution

During the 1700s and 1800s the idea of evolution — in manifold expression and form — begins to take hold of the Western mind (see also Teichmann 2005). Robert Hooke was one of those brilliant polymath scientists of the early eighteenth century who seemed to think about everything and made original observations in many different areas of inquiry. He writes, in 1705, about geological processes:

Many places which by degrees are made submarine, will be covered with various layers or coats of earth. As the parts of the land are continually washed down, and by the rivers carried into the sea, and there deposited in submarine regions, so much more powerfully and plentifully are the higher parts of the submarine regions by tides, currents and other agitations of the water, removed from the lower, partly sinking out of the muddy water, but principally by tumbling and rolling down from the higher, which . . . must be posited in certain layers or stratifications of divers kinds of substances according to the nature of those which are this or that way brought thither, and there deposited. (Cited in Edwards 1967, p. 3)

What a dynamic view of the processes of erosion, sedimentation and rock-layer formation! This is no static world. And, for Hooke, organisms are part of this dynamism:

There have been many other species of creature in former ages, of which we can find none at present; and ‘tis not unlikely also but that there may be divers new kinds now, which have not been from the beginning . . . . There may have been divers new varieties generated of the same species, and that by the change of the soil on which it was produced; for since we find that the alteration of climate, soil and nourishment often produce a great alteration in those bodies that suffer it; ‘tis not to be doubted that the alterations of this nature may cause a very great change in the shape and other accidents of the animated body.

He's talking about species changing in 1705. That's 155 years before Darwin's Origin of Species. It's important to realize what Darwin was already building on (see Eiseley 1961, Glass et al. 1968). He was building on a great deal of previous thought and experience when he wrote Origin of Species. Hooke has made the transition to evolutionary thinking. He talks about dynamic processes in the earth, and it makes sense to him that species can change. He is looking at the same fossils that others in his time are looking at, but he is seeing them differently. He's looking with a different mind. So something is evolving in human consciousness: one can look at things in terms of evolution and see dynamic processes where others have seen a revelation of eternity.

Another person who wrote about evolution, now in the latter part of the eighteenth century, was Johann Gottfried Herder, who was a good friend of Goethe. Herder wrote extensively about the history of humanity and the earth. He views everything in terms of development. He talks about the development of the earth, the development of organisms, the development of language, and the development of cultures. Nothing was static for him, things were always moving from one state to the next. He writes in 1774:

Air, fire, water, and the earth evolve out of the spiritual and material . . . in periodic cycles of time. Diverse connections of water, air, and light precede the emergence of the seed of the simplest plant, for instance, moss. Many plants had to come into being and then die away before an animal emerged. Insects, birds, water animals, and night animals preceded the present animal forms until finally the crown of earthly organization appeared — the human being, the microcosm . . . . He must be the youngest child of nature. Many evolutions and revolutions must have preceded his formation. (Cited in Teichmann 2005, p. 2)

In Herder's mind, the great chain of being has become temporal. The earth and its inhabitants evolve and what arises later can only develop because it can build on what has evolved before it. For Herder, evolution is clearly progressive, “nothing in Nature stands still; everything strives and moves forward” (cited in Teichmann 2005, p. 2).

Dynamic Earth, But Static Species

The transition to evolutionary thinking was — and in some ways we can say, it still is — a struggle. Not all thinkers embraced evolution the way Hooke or Herder did. Take Charles Lyell, the British geologist who was also a mentor of Darwin’s. The three substantial volumes of his Principles of Geology, written in the 1830s, constituted one of the first authoritative geology textbooks. In it Lyell describes the ages of the earth and the different kinds of geological process. Like Hooke, he sees the earth in a dynamic way. He's also the scientist who made a strong case for the view that the earth must be old — many thousands of years older than a literal reading of the Bible would have people believe.

Lyell observed that the upper earth crust consists of rock that lies in layers. Many of these layers contain fossils. He concluded that such layers are layers of sedimentary rock — laid down by deposition in water or by wind. If they are sediments, then what is at the bottom is older than what is on the top. Since the process of sedimentation is slow and takes a long time, the deep layers of sedimentary rock must be very old, and they are often resting on top of even older layers of igneous and metamorphic rocks. Lyell assumed that sedimentation processes have in all ages proceeded at about the rate they proceed today. This assumption, called “uniformitarianism,” remains at the heart of geophysical thinking today.

In this geological view, time became immense. In a sense time became infinite, not in the sense of eternal, but infinite in the sense of receding into a hardly fathomable, unreachable past. This huge expanse of time provides a very important context for evolutionary theory later on. Since Darwin imagined the change of species to be a slow and gradual process, it would have been unimaginable without a vast expanse of time in which slow transformation could occur.

Now the interesting thing is that, in the second volume of his book, Lyell takes issue with the idea of the transmutation of species, that is, the change of species over time. He saw the earth dynamically, but was not willing to acknowledge the evolutionary transformation of organisms. Lyell knows his geology inside and out, and he is familiar with fossil remains. But he says species do not evolve.

Lyell believed that God created all of the species at the beginning of time and that their existence is preordained:

We must suppose that when the Author of Nature creates an animal or plant, all the possible circumstances in which its descendents are destined to live are foreseen, and that an organization is conferred upon it which will enable the species to perpetuate itself and survive under all the varying circumstances to which it must inevitably be exposed. (Lyell, 1832/1991, vol. 2, p. 23-4)

At the end of this part of his book, Lyell concludes that species are real entities. They may have variability and adaptability, but in principle they stay the way they were when God created them. There is no evolution of species; they do not transgress their God-given boundaries. When Charles Darwin, his protégé, a few decades later came out full force with the idea of the transmutation of species, Lyell was deeply troubled. He didn't like the idea, although later on, under Darwin's influence, his view shifted.

Darwin's Discovery of Evolution

In 1837 Darwin made his first sketch of a hypothetical evolutionary “bush” — various species having diverged from one ancestral species.

Already as a teenager Charles Darwin heard through his mentor Robert Grant about the “heretical” evolutionary ideas of the French scientist Lamarck and others. At the same time, Darwin was a hunter and keen naturalist. While studying at Cambridge, “his one serious sport, was the pursuit of beetles” (Desmond and Moore 1991, p. 57). He took extensive botanical walks with the Reverend John Stevens Henslow, who was also a professor of botany at Cambridge. He learned geology from the Reverend Adam Sedgwick, one of the main authorities on geology at the time. Darwin's desire to explore the breadth of the natural world was reinforced by his reading of Alexander von Humboldt's seven-volume narrative about his trip to South America. When the opportunity arose to apply for the station of naturalist and captain's companion aboard the Beagle, a ship that was to sail around the globe, he jumped at the opportunity.

The voyage began in 1831 — Darwin was 22 years old — and lasted until 1836. When onshore in South America he avidly collected fossils and remarked in a letter home, that “the pleasure of the first days partridge shooting . . . cannot be compared to finding a fine group of fossil bones, which tell their story of former times with almost a living tongue” (cited in Desmond and Moore, 1991, p. 144). He also collected plants and animals and had them shipped back to England for further investigation. During these years Darwin immersed himself in the manifold variety of nature. He had eyes that appreciated small differences, such as the visible differences between mockingbirds on different islands of the Galapagos Islands. And it was not lost on him that such observations had the potential to “undermine the stability of species” (cited in Eiseley, 1961, p. 172).

The significance of much of what Darwin observed and collected became clearer to him — and to others — only after it was ordered and reflected upon in the years following the voyage. For example, during his visit to the Galapagos Islands, Darwin had been confused by finches and similar birds that inhabited the different islands. Back in London, ornithologist John Gould studied the specimens and came to the conclusion that there were in fact twelve different species of finches — perhaps the most astounding case of bird species diversity within a small geographical area that had been discovered up until then. Another scientist investigated the shells of the giant Galapagos tortoises and realized that they were indigenous to these islands and showed, like the finches, a remarkable diversity.

By mid-March 1837 — having recently turned 28 years old — Darwin had become an evolutionist. The Galapagos organisms, for example, now showed him that some original immigrant species to the islands must have changed over time and developed into a number of different species. How else could the phenomena be intelligently explained? He writes later in his book, The Voyage of the Beagle (Darwin, 1979):

Most organic productions on these islands are aboriginal creatures; found nowhere else; there is even a great difference between the inhabitants of the different islands; yet all show a marked relationship with America, though separated from that continent . . . by 500-600 miles . . . . The archipelago is a little world within itself, or rather a satellite attached to America, whence it has derived a few stray colonists, and has received the general character of its indigenous productions. Considering the small size of these islands we feel the more astonished at the number of their aboriginal beings, and at their confined range. Seeing every height crowned with its crater, and the boundaries of most of the lava streams still distinct, we are led to believe that within a period, geologically recent, the unbroken sea was spread out here. Hence, both in space and time, we seem to be brought somewhat nearer to that great fact — that mystery of mysteries — the first appearance of new beings on this earth. (p. 363)

In reference to the different species of finches — which later became known as the “Darwin finches” — he writes:

Seeing this gradation and diversity of structure in one small, intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends. (p. 365)

In the shift from the creationist thinking of those times to an evolutionary view of the earth and its organisms, the world becomes dynamic. It is a shift from a more static world view to a perception of a world in flux. For Darwin it must have been like breaking through the ice of an encrusted world view.

Darwin's Theory

It is one thing to become convinced, on the basis of careful attention to the modifications of organisms, that evolution must occur. It is another matter to explain what causes evolutionary change. This was the challenge that Darwin took up.

Back in England, first in London and then at his country home in Kent, Darwin pondered the causes of evolution. He continued to gather evidence of evolution and began crafting his theory. In 1842 he wrote a first, thirty-five page sketch of his theory (in Darwin 2008). He did not share it with anyone, and it already contained many of the key elements of what he published in Origin of Species. In the following years, Darwin had many other publishing commitments and undertook as well an in-depth study of the biology and classification of barnacles.

When Darwin began the work on barnacles, he remarked on his “extraordinary pleasure in pure observation.” Concluding the work six years later he said, “I am at work on the second vol. of the Cirripedia [barnacles], of which creatures I am wonderfully tired: I hate a Barnacle as no man ever did before, not even a Sailor in a slow-sailing ship” (cited in van Wyhe 2007, pp. 191-2).

During this time he nonetheless continued to carry out his studies on evolution and corresponded with numerous people about that work. He began writing in earnest in 1856 and had completed “two-thirds of the topics later discussed in Origin of Species” by spring 1858 (van Wyhe 2007, p. 193). At this time a letter from Alfred Russell Wallace arrived, describing Wallace's own theory of evolution, which was remarkably similar to Darwin's — the idea was evidently “in the air.” Darwin completed Origin of Species in spring 1859, and it was published in the fall.

In his theory, Darwin appealed to some basic biological facts. First, the individuals of one species differ from one another in more or less subtle ways. He recognized that there is no rigid boundary to a species and that it is not always possible to tell to which species a given individual belongs. Second, organisms produce more offspring than survive. If all the seeds grew into fully developed plants or all young animals survived until reproductive age, and they and their offspring continued to reproduce, the world would quickly be overpopulated. But this doesn't happen: offspring die, are eaten by other creatures, and not all adults are fertile or mate.

Darwin believed that if you take these two aspects of biological life together — variation and overproduction of offspring — something significant follows: there is a struggle for life and only some — the best adapted — will survive and in turn reproduce:

Owing to this struggle for life, any variation, however slight and from whatever cause proceeding, if it be in any degree profitable to an individual of any species, in its infinitely complex relations to other organic beings and to external nature, will tend to the preservation of that individual, and will generally be inherited by its offspring. The offspring, also, will thus have a better chance of surviving, for, of the many individuals of any species which are periodically born, but a small number can survive. I have called this principle, by which each slight variation, if useful, is preserved, by the term of Natural Selection . . . (Darwin 1859/1979, p. 115)

Since this process, in Darwin's view, is unceasing, the number of small adaptive traits will gradually accumulate in a line of offspring and it will diverge from its original ancestor. In this way, over long periods of time (you see now the importance of the vast ages of earth history), new species can arise.

What causes organisms to vary and how the variations become inherited (or not) was not clear to Darwin. He did not simply posit random variation, which is how Darwin's view is often taught today. The idea of random variation became the twentieth century's narrow and codified view of Darwinism, based on subsequent knowledge of genetics and genetic mutations. Darwin himself held much more tentative views. He believed, for example, like Lamarck before him, that the changed habits of an organism could become inherited.

In the Origin of Species, which is over four hundred pages long, Darwin looks at a great variety of phenomena that he feels can be explained in light of his theory of natural selection. It is for him an exceedingly powerful and convincing framework in which to understand organisms and their history. There is, on Darwin's view, a kind of unwavering, unsentimental force of logic at work in nature and in evolution: “All that we can do, is to keep steadily in mind that each organic being is striving to increase at a geometrical ratio; that each at some period of its life, during some season of the year, during each generation or at intervals, has to struggle for life, and to suffer great destruction” (1859/1979, p. 128). Amidst this destruction, “the vigorous, the healthy, and the happy survive and multiply” (ibid.). They carry the seeds of evolution into the future. For Darwin, as he says at the end of the book, “there is grandeur in this view of life,” because “from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of higher animals, directly follows” (p. 459).

In Origin of Species Darwin does not touch on human evolution except to remark that “light will be thrown on the origin of man and his history” (p. 458). That light he brought to the public in his 1871 book, Descent of Man. There Darwin discusses human evolution and how humanity evolved from monkey or ape-like ancestors.

What aroused both supporters and antagonists was that Darwin's theory was purely naturalistic. It didn't need God or some other divine plan. It showed how life could unfold and evolve according to a few causal mechanisms through which “endless forms most beautiful and most wonderful have been, and are being, evolved,” as Darwin says reverently at the conclusion of Origin of Species (p. 460). For others, this naturalistic world, devoid of God and of underlying purpose was — and is — a nightmarish vision of reality.

Darwin and Beyond

Darwin remained interested in and intrigued by the diversity of nature throughout his life. Again and again he would dive into some new area of natural history — orchids, plant movements, earthworms — and become deeply knowledgeable about that area. It's hard to believe how much of nature's bounty he was able to take in — especially in light of the fact that due to chronic poor health he often could only work a few hours a day.

So, on the one hand, we have the picture of the avid naturalist, a man who loved to study plants and animals in all their details and with a keen eye for variety and variation. The dynamism of the world spoke to Darwin through his loving attention to what the phenomena showed him. On the other hand, as he stated in his autobiography, "my mind seems to have become a kind of machine for grinding general laws out of large collections of facts" (2005, p. 54). The more general a law becomes, the less it says about any given concrete phenomenon. A tension arises between the richness of the world and the abstract, all-encompassing law. There is little problem as long as we remain aware of this tension and never lose sight of what a generality may not be addressing.

The problem, however, is that those who seek to formulate general laws are often possessed by the desire to explain everything within the realm of phenomena with which they are dealing. Darwin did believe he had a general theory that explained how all life forms evolved since the first life appeared on earth. What didn't seem to bother Darwin was that he was borrowing an idea of competition and struggle for existence that had been developed in connection with human social and economic life, most starkly represented in Thomas Malthus’ influential 1798 book, An Essay on the Principle of Population. Darwin states that his theory is “the doctrine of Malthus applied with manifold force to the whole animal and vegetable kingdoms” (1859/1979 p. 117). So he took an idea that had been developed in relation to one area of phenomena and within a specific historical and social context, generalized that idea, and applied it to the entire realm of life.

Darwin's theory took hold firmly in twentieth-century biology and became — in a more rigid form than Darwin held it — the primary lens through which every budding biologist learns to view any given biological phenomenon. Darwinism has become, in Kuhn's phrase, the dominant paradigm and part of “normal science” (Kuhn 1996).

When a theory becomes the sole lens through which you are “allowed” to look at the world, it becomes stultifying. This is what Darwin and his contemporaries felt when they were continually confronted with the “self-evident” reality of species and the idea that species don't evolve. As he wrote in his autobiography, “I occasionally sounded not a few naturalists, and never happened to come across a single one who seemed to doubt about the permanence of species” (2005, p. 101). He worked against this stream and established a new way of looking at things.

The question is whether it is not time — 150 years after Origin of Species — to take once again a fresh look at evolutionary phenomena, not denying what Darwin discovered, but also not taking his theory as the “truth” to be demonstrated. One of the sad features of the popular understanding of evolution today is the conflation of standard Darwinian explanation of evolution with the phenomena themselves that point to evolution. Already before Darwin, during his lifetime and since his death in 1882, there have been other views of evolution. Many philosophers and scientists have argued that many phenomena are not adequately addressed through a Darwinian adaptationist framework. (To discuss the various non-adaptationist views is not possible in this essay, but I have included a bibliography at the end of this article.)

In this issue of In Context #21, you can read about the work of two scientists who have discovered patterns of biological form that are not illuminated by conventional Darwinian functional explanations. They present a clear challenge to Darwin's belief that “nature cares nothing for appearances, except in so far as they may be useful to any being” (1859/1979, p. 132).

In the first sections of this essay I described a time in which naturalists did not “see” evolution. This changed. Today most people who study nature “see” evolution. Over time the Darwinian perspective became dominant as an all-encompassing and powerful explanatory framework that fits well with the modern propensity of mind to find general laws. Because it has become the dominant, established paradigm, we are in danger of letting it constrict our view of life as the sole lens through which we look.

As biologist Lynn Margulis, who is an iconoclast and not someone who simply heeds conventional scientific wisdom, wrote in a critical editorial a couple of years ago in American Scientist:

Evolutionary biologists act certain that they know how new life forms originate and complexify. But they don't . . . . Many biologists claim they know for sure that random mutation (purposeless chance) is the source of inherited variation that generates new species of life and that life evolved in a single-common-trunk dichotomously branching-phylogenetic tree pattern. “No!” I say. Then how did one species evolve into another? This profound research question is assiduously undermined by the hegemony who flaunt their “correct” solution . . . . Our zealous research, ever faithful to the god who dwells in the details, openly challenges such dogmatic certainty. This is science. (Margulis 2006, p. 194)

The notion of evolution is itself an idea that has emerged and evolved over the past centuries. Thankfully, it is greater than any particular theory about it can possibly encompass. There is every reason to hope that the human mind, through careful engagement with the vast richness and diversity of the living world and an ever-evolving will to see things more deeply and adequately, will be able to break through present-day constrictions to ever grander views of this life.

References

Barfield, Owen (1988). Saving the Appearances. Middletown CT: Wesleyan University Press.

Darwin, Charles (1859/1979). Origin of Species, first edition. New York: Penguin Books.

Darwin, Charles (1871/1981). Descent of Man. Princeton: Princeton University Press.

Darwin, Charles (1979). The Voyage of the Beagle. London: J. M. Dent & Sons Ltd. (First published in 1839 and then revised in later editions; the version cited here includes later revisions.)

Darwin, Charles (2005). The Autobiography of Charles Darwin, edited by Nora Barlow. New York: W. W. Norton. (This “restored” version of the autobiography was first published in 1958; earlier versions had been strongly edited by Darwin's family.)

Darwin, Charles (2008). The Foundation of the Origin of Species, edited by Francis Darwin. Bibliobazaar. (This book contains the 1842 and 1844 essays on evolution; it was originally published in 1909.)

Desmond, Adrian and James Moore (1991). Darwin. New York: W. W. Norton & Company.

Edwards, W. N. (1967). The Early History of Palaeontology. London: Trustees of the British Museum of Natural History.

Eiseley, Loren (1961). Darwin's Century. Garden City NY: Anchor Books.

Glass, Bentley, Owsei Temkin, and William Straus, editors (1968). Forerunners of Darwin 1745 - 1859. Baltimore: John Hopkins University Press.

Kuhn, T. S. (1996). The Structure of Scientific Revolutions, third edition. Chicago: University of Chicago Press.

Lovejoy, Arthur (1976). The Great Chain of Being: A Study of the History of an Idea. Cambridge, MA: Harvard University Press.

Lyell, Charles (1991). Principles of Geology, vols. I - III. Chicago: University of Chicago Press. (The three volumes were originally published between 1830 and 1833.)

Margulis, Lynn (2006). “The Phylogenetic Tree Topples,” American Scientist vol. 94, p. 194.

Schuchert, Charles (1924). A Textbook of Geology, Part II (“Historical Geology”). New York: John Wiley & Sons, Inc.

Teichmann, Frank (2005). “The Emergence of the Idea of Evolution in the Time of Goethe,” Research Bulletin of the Research Institute for Waldorf Education vol. 11. Available online: http://www.waldorfresearchinstitute.org/pdf/BAIdeaEvolTeich.pdf

Van Wyhe, John (2007). “Mind the Gap: Did Darwin Avoid Publishing His Theory for Many Years?” Notes and Records of the Royal Society vol. 61, pp. 177-205.

Selected Bibliography of Non-Adaptationist Perspectives on Evolution

This bibliography is by no means exhaustive; it is meant to point the reader to a variety of views on evolution that go beyond Darwinism. It does not include books and articles that are primarily critiques of Darwinism.

Berg, Leo (1969). Nomogenesis or Evolution Determined by Law. Cambridge MA: MIT Press. (Originally published 1922 in Russian.)

Bowler, P. J. (1988). The Non-Darwinian Revolution. Baltimore: Johns Hopkins University Press.

Eldredge, N., and S. J. Gould (1972). “Punctuated Equilibria: An Alternative to Phyletic Gradualism,” in Schopf 1972.

Goodwin, Brian (2001). How the Leopard Changed its Spots: The Evolution of Complexity. Princeton: Princeton University Press.

Goodwin, Brian, and Gerry Webster (1996). Form and Transformation: Generative and Relational Principles in Biology. Cambridge, UK: Cambridge University Press.

Gould, S. J. and R. C. Lewontin. (1979). “The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme,” Proc. Royal Soc. Lond. B vol. 250, pp. 581-98.

Gutmann, Wolfgang (1995). Die Evolution hydraulischer Konstruktionen: Organismische Wandlung statt altdarwinistischer Anpassung. Stuttgart: E. Schweizerbart.

Ho, Mae-Wan, and P. T. Saunders, editors (1984). Beyond Neo-Darwinism: An Introduction to the New Evolutionary Paradigm. London: Academic Press.

Holdrege, Craig (2005). The Giraffe's Long Neck. Ghent NY: The Nature Institute.

Kranich, Ernst-Michael (1999). Thinking Beyond Darwin: The Idea of the Type as a Key to Vertebrate Evolution. Great Barrington MA: Lindisfarne Books.

Kropotkin, Peter (1914). Mutual Aid: A Factor of Evolution. Reprint of the 1914 edition. Boston: Porter Sargent Publishers, Inc. (Originally published 1902 in Russian.)

Lockley, Martin and Phyllis Jackson (2008). “The Morphodynamics of Dinosaurs, Other Archosaurs, and Their Trackways: Holistic Insights into Relationships between Feet, Limbs, and the Whole Body,” SEPM Special Publications No. 88, pp. 27-51.

Margulis, Lynn and Dorian Sagan (2003). Acquiring Genomes. New York: Basic Books.

Portmann, Adolf (1967). Animal Forms and Patterns. New York: Schocken Books.

Riedl, Rupert (1978). Order in Living Organisms: A Systems Analysis of Evolution. New York: John Wiley & Sons. (Originally published 1975 in German.)

Riegner, Mark (1998). “Horns, Hooves, Spots, and Stripes: Form and Pattern in Mammals,” in Seamon and Zajonc 1998, pp. 177-212.

Riegner, Mark (2008). “Parallel Evolution of Plumage Pattern and Coloration in Birds: Implications for Defining Avian Morphospace,” The Condor vol. 110, pp. 599-614.

Schad, Wolfgang (2008). “Evolutionsbiologie heute — Zum Darwin Jahr 2009: 150 Jahre seit Origin of Species,” Jahrbuch für Goetheanismus 2008/2009. pp. 7-37.

Schad, Wolfgang (1993). “Heterochronical Patterns of Evolution in the Transitional Stages of Vertebrate Classes,” Acta Biotheoretica vol. 41, pp. 383-9.

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