Background to Darwin

Guide for this Unit:
The Background to Darwin in Anatomy, Physiology, Systematics, and Phylogeny
The Background to Darwin in Geology and Philosophy
Study Questions for this Unit

Readings for this Unit:
Vesalius and the New Anatomy
Harvey and the New Physiology
Linnaeus and the New Systematics
Lamarck on Evolution
Comte on Philosophy
Harvey and the New Physiology
Whewell on Lyell's Uniformity in Geology
Lyell's Critique of Lamarck
Lyell's Defence of Darwin

The Background to Darwin in the new Anatomy, Physiology, Systematics, and Phylogeny

This week, we'll first look at four significant works over four centuries which form a significant part of the background to Darwin. I will use these -- especially the first three -- to argue that an important way of looking at Darwin's work is that he completes a scientific revolution in biology begun by Vesalius, Harvey and Linnaeus (and hinted at by Lamarck), through his theory of evolution:

1. Andreas Vesalius (1514-1564), published his defining work, De Humani Corporis Fabrica. (On the Fabric of the Human Body) in 1543. Coincidentally, this was the year that Copernicus published his De Revolutionibus Orbium Caelestium (On the Revolutions of the Heavenly Orbs), which began the astronomical revolution by arguing that the sun, not the earth, is the center. Click here: to read about Vesalius.

2. William Harvey (1578-1657), published De Motu Cordis... (Anatomical Exercises Concerning the Motion of the Heart and Blood in Living Creatures) in 1629. His work, which demonstrated the circulation of the blood, was an important influence on the mechanistic views of the philosopher Rene Descartes. Click here: to read about Harvey.

3. Carl von Linnaeus (1707-1778) published his Systema Natura (System of Nature), 1735, constantly expanding it until the 12th and final edition of 1760. This work broke new ground by classifying flowers according to their sexual parts (stamins and pistels), and by including humans, "homo sapiens" in the two-part name given us by Linnaeus, included (in later editions) in the genus of the "primates" to which we still belong. Click here: to read about Linnaeus .

4. Jean Baptiste Lamarck (1744-1829) published his Zoologie Philosophique (Philosophical Zoology) in 1809. This was the first work to place the concept of species evolution at the center of a book-length treatment. Earlier, Georges Buffon (1707-1788) had argued in his great Histoire Naturelle (Natural History) that asses and zebras had descended from horses, but this was just a passing reference. Lamarck's work served as both an impetus to Darwin, showing that the concept could be systematically treated, and as a warning, because of the poor reception granted the work by Lamarck's colleagues and its vague, barely scientific mechanism to explain the process of species change. Click here: to read about Lamarck .

My thesis for this part of the course is as follows: The new descriptions of human anatomy due to Vesalius, human and animal physiology due to Harvey, and species classification -- including both plants, animals and humans -- due to Linnaeus begin a scientific revolution in biology. For this, I'll be borrowing some of Thomas Kuhn's theory of scientific revolutions. Click here: to read about Kuhn. Lamarck attempts to provide an explanation for these new descriptive discoveries, but is unsuccesful, for reasons we shall see later. Darwin succeeds -- although not fully -- in providing that explanation in his theory of evolution, especially through his concepts of "natural selection" and "descent with modification" leading to the "origin (and evolution) of species".

The Background to Darwin in Geology and Philosophy

We will now consider two further aspects of the background to Darwin, in the work of his contemporaries, the geologist Charles Lyell and the philosopher Auguste Comte.

Comte's Three Stages of the Evolution of Science

While Charles Darwin was away on his around the world voyage of discovery on board H. M. S. Beagle, from 1832-36, the French philosopher Auguste Comte began the publication of his multi-volume work Philosophy of Positive Science In it, Comte argued that all sciences pass through three stages:

  1. The first stage is the "theological stage", when the cause of natural phenomena is believed to be supernatural in nature, involving a deity of some sort. For example, lightning was believed by the ancient Greeks to be an expression of the anger of the god Zeus, while at the very earliest stage of Greek cosmology, it was believed that the stars were moved in their orbits by gods who directed them as a charioteer directs a chariot.
  2. The second stage is the "metaphysical stage", where the cause of natural phenomena is believed to be some inner essence or nature of the thing in question. For example, Aristotle argued that the stars moved in circular orbits, not because they were dragged about by divine charioteers, but because they were made of the element "aether", whose essence or inner nature was to move in a circular motion.
  3. The third stage is the "positive stage", when scientists give up the search for supernatural causes or inner essences, and focus on the discovery of the correlations between antecedent causes and subsequent effects. For example, a "positive" understanding of planetary motion was first achieved by Johannes Kepler, who noted that a certain numerical relationship existed between the average distance of a planet from the sun and the total time of its orbit around the sun (the square of the period of revolution divided by the cube of the average distance is a constant -- the same -- for all planets).

Darwin read about Comte's work on his return from the Beagle voyage, from a review of Positive Philosophy which appeared in the Edinburgh Review. Comte provided a methodological basis for a naturalistic world view in science, even if in biology he was not an evolutionist. Click on the following link to read Comte's theory in his own words. We know what Darwin was thinking during the crucial period of 1836-38 when he formulated his idea of natural selection (even though he only published it more than 20 years later) because his notebooks from that period have been discovered and were published in the 1960s: The influence of Comte can be seen in the M Notebook as follows:

"Now it is not a little remarkable that the fixed laws of nature should be / universally / thought to be the will of a superior being, whose natures can only be rudely traced out. When one sees / this, one suspects that our will may / arise from / as fixed laws of organization. - M. le Comte argues against all contrivance - it is what my views tend to."(M.69

The following quote, though only programmatic, also indicates the profound influence of Comte on Darwin's whole view of biology: "M. le Comte's idea of theological state of science, grand idea: ... as soon as any enquiry commenced, for instance probably such a thing as thunder would be placed to the will of God.- Zoology itself is now purely theological." (N.12)

Darwin was clearly dissatisfied with this theological state of zoology. In the notes to Maculloch's Proofs and Illustrations of the Attributes of God (1832) which have been transcribed by Paul Barrett under the title "Essay on Theology and Natural Selection," Darwin rejected any theological explanation of the cause of species:

"The explanation of types of structure in classes - as resulting from the will of the deity, to create animals on certain plans, - is no explanation - it has not the character of a physical law /& is therefore utterly useless. - it foretells nothing / because we know nothing of the will of the Deity, how it acts & whether constant or inconstant like that of man. - the cause given we know not the effect."

The rejection of supernatural ;agency and theological explanation was a constant feature of Darwin's further writings. Darwin meant to transform zoology from its theological to its positive stage, a task he was to accomplish with his theory of evolution by natural selection. Comte's classification can be applied to species origin as follows:

  1. First or theological stage: Species are specially created by a divine being, in their present state and with their present functions, adapted to their environment.
  2. Second, or metaphysical stage: Species progress through transformations ("transmutations") due to an inner essence or driving force of "perfection".
  3. Third, of positive stage: Species originate and develop through the mechanism of "natural selection", surviving with modifications depending on whether they have the needed variations to "fit" with a changing environment they cannot predict in advance.

Lyell's principle of uniformity

A second major influence on Darwin's thinking was the "principle of uniformity" which the geologist Charles Lyell (1797-1875) set out in his multi-volume work, Principles of Geology, which like Comte's Positive Philosophy appeared around the period when Darwin was away on his voyage of discovery. Darwin, who knew Lyell personally, took the first volume -- just published -- with him, and had subsequent volumes sent by mail ship to his ports of call along the South American coast.

Lyell was by training a barrister, or lawyer, but his real love was for geology. During the first half of the 19th century, it was not unusual for scientists to have self-trained in their field (as was Darwin himself, whose training was more in medicine and theology than in biology proper).

Lyell took to task the then dominant theory in geology -- the view that major geological features were due to catastrophic forces, unlike those currently at work, which had acted in the past. When combined with natural theology, there was added the claim that these past catastrophes were the work of God, transforming the world through a creation process (as stated in Genesis) or through a great flood (such as the flood that Noah and his animals survived in the ark).

At the time Lyell was writing, the age of the world was generally supposed to be somewhat less than 6000 years -- the date of 4004 BC having been calculated as the Biblical date of the origin of the earth by Bishop Usher, who used the chronology of fathers and sons in the Old Testament to come up with this number. The Flood was taken to be the last of these cataclysms, but due to the discovery of geological strata in the rocks with fossils of species no longer living, it was also assumed that in the first 2000 years leading up to the Flood, the catastrophic mode of action was common. (Incidentally, this theory divides world history nicely into three (from a Christian fundamentalist perspective)-- the first 2000 years of catastrophic events, concluding in the Flood; the second 2000 years that of the Biblical era leading up Christ; the third 2000 years the Christian era leading up to the return of Christ; hence the importance of the year 2000 not only for computer specialists but for messianic Christians).

Lyell, however, doubted that unknown catastrophic forces could be responsible for geological structures, and instead, argued for the slow but cumulative action of causes similar to those presently existing. For example, a mountain could be uplifted by continual flow of magma from the beneath the surface of the earth, or be worn away through the slow but persistent action of wind and rain. In order to stress this aspect of his theory, Lyell subitled his Principles of Geology as follows: "An Attempt to Explain the Former Changes of the Earths Surface by Reference to Causes now in Operation".

The terminology of "uniformity" vs "catastrophe" was not due to Lyell himself, but rather was coined by William Whewell, a reverend and mathematician who wrote one of the Bridgewater Treatises on natural theology. In the final chapter of his three volume History of the Inductive Sciences, published in 1837, Whewell analyzed the controversy in geology as due to the presence of "two antaogonistic doctrines" - those of catastrophism and uniformitism. His sympathises lay with the latter, the new view of Lyell. Click here to read Whewell's discussion of uniformity.

Now, the doctrine of uniformity, were it applied to biology, and more specifically to species, would be "an attempt to explain the former origin of species by reference to causes now in operation", to paraphrase Lyell's subtitle for his book. Special creation of species would fall under "catastrophism", and be replaced by a search for small, continually acting forces that would bring about new species. This is what Darwin can be seen as doing in his Origin of Species. In this he was initially in disagreement with his friend and colleague Lyell.

Lyell, in the first edition of his Principles of Geology (1837), Lyell presented Lamarck's theory of species transmutation and criticized it. Click here to read Lyell's critique of Lamarck.. But even before Darwin published his Origin of Species (1859), Darwin met with Lyell to explain his new theory, and Lyell was won over, in large measure because Darwin's "natural selection", acting slowly and accumulating small changes over long periods of time was consistent with Lyell's principle of uniformity. Click here to read Lyell's defence of Darwinism, in the sixth and subsequent editions of Principles of Geology. Just as "special creation" was a theory of species origin that meshed well wit "natural theology", so too did "natural selection" as a biological theory mesh well with the "principle of uniformity" as a general scientific framework for biology as well as for geology.

Study Questions

Study Questions for Anatomy, Physiology, Systematics and Phylogeny

(1) What was the major innovation due to Vesalius?
(2) How did Harvey argue for the circulation of the blood?
(3) What was the principle upon which Linnaeus based his classification of species?
(4) What was the major innovation due to Lamarck?

Study Questions for Geology and Philosophy

(1) What are the three stages in Comte's theory of how science progresses?
(2) What stage would Darwin associate with the theory of special creation?
(3) What is the principle of uniformity in geology?
(4) How would this principle apply to the origin of species?