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This is the first in what will be (hopefully) a series of diaries posted at irregular intervals. The purpose of these diaries is to give an overview of genuine evolutionary controversies that have cropped up over the last 150 years, as opposed to the social controversies that creationists contrive and then try and pass off as scientific disagreements. Amazingly, people studying evolution are not losing sleep over the second law of thermodynamics, supposed failures of carbon dating, supposed fossil human footprints mixed in with those of dinosaurs, the failure of apes to vanish off the face of the earth after the origin of humans, the lack of half cat/half dog fossils, and the failure of brand new forms of life readily recognizable as such to even the most wholly ignorant of biology to appear every second Thursday.

Important Caveat: My training is in the general area of evolutionary ecology with substantial exposure to evolutionary genetics. I am also married to someone who does research in the field of evolutionary genetics. My knowledge of paleontology is definitely less than comprehensive and of geology in general, pretty rudimentary. I am slated to teach our Evolution course this summer so writing this series will be a good way of strengthening my weaknesses. In addition to questions (always welcome) corrections or challenges are also encouraged.

This introductory diary discusses topics in European science relevant to evolutionary biology from the 17th century through the first half of the 19th century. Similar ideas had been proposed by Greek, Roman and Islamic scholars (and possibly others) in the more distant past. However the foundations of modern biology really begin in the 1600s and the work of the last few centuries is much more directly foundational to Darwin's ideas and what has come afterward.

The 1600s In this period the foundations of modern biology were laid down. Scholars such as Antony van Leeuwenhoek (1632-1723) and Robert Hooke (1635-1703) used microscopes to discover new forms of life and also to reveal that living things were composed of smaller units known as cells. John Ray (1628-1705) developed a system of classification encompassing all living things and made numerous observations of the morphology (physical structure) of organisms. He strongly linked the form of organismal structure to its function, one of the most fundamental underlying tenets of biology. Most importantly from an evolutionary standpoint, Ray, Hooke, and Nicholas Steno (1638-1686) all worked to establish the fact that fossils were the remains of once living organisms (this had been hypothesized previously but never studied in detail). Steno also did important work in understanding the physical and chemical processes through which fossilization could occur and through which other geological features could be formed.

So what we see in this period is the discovery that life is much more diverse than previously imagined but also has a unifying underlying structure. Life's unity is emphasized in that all of life can be classified in a single system. There is a strong link between the structure of organisms and their function. And most importantly, the existence of fossils implies both that the earth is ancient and that life on earth differed in the past from what we see today.

It is important to note that this work was largely pursued and analyzed through the lens of Christian theology. In particular, Ray's work was motivated by the desire to see the hand of god in nature. Ray was the intellectual father of Natural Theology. Natural Theology is the idea that the study of nature leads to the discovery of the mind of god. This was a view strongly espoused by William Paley (1743-1805) in the 18th Century and was very influential in science up until the Darwinian era. Today it is the philosophical basis of Intelligent Design arguments.

Linnaeus and Hierarchical Classification Carl von Linne (1707-1778) better known by the Latinized version of his name Carolus Linnaeus is probably the most famous biologist of the 18th century. His most important contribution is a standardized system of classifying organisms that is still in use today in modified form. A key feature of this scheme is that it is hierarchical, that each named group falls wholly within a single larger group. For example all bears are members of the family Ursidae. The Ursidae falls within the order Carnivora. All bears are members of the Carnivora therefore, including the Panda which does not eat meat. The importance of this hierarchical classification became apparent to Darwin as he saw it as a reflection of evolutionary history. Linnaeus himself was a natural theologian and did make any evolutionary inferences from his work.

Comte de Buffon and Erasmus Darwin These two scholars stand out as pioneers in the 18th century whose ideas were really ahead of their time. Georges-Louis Leclerc, Comte de Buffon (1707-1788) was a French aristocrat who published an enormous multi-volume work the attempted to summarize everything known about the natural world at that time. In it he speculated about the common ancestry of apes and humans and proposed that the environment acted on species to drive evolutionary change. In later works he proposed that the earth was ancient. Buffon's work suffered from a lack of a coherent mechanism for his ideas, proposing that the environment directly caused evolutionary change without specifying how this would happen. He was also highly inconsistent in his attitude towards the evolution of new species, proposing it and rejecting it throughout his work. To some extent he also made similar claims to the uniformitarian geologists but several decades earlier.

Erasmus Darwin (1731-1802) was Charles Darwin's grandfather and formidable polymath. He was a doctor, who turned down the position of physician to the king and treated the poor for free. He championed education for women, supported the Amercian revolution and despised slavery. Dr. Darwin made a wide number of contributions to natural history and other areas of science. He also wrote poetry, was a deist, and an advocate of 'free love' (his two illegitimate children were raised as equals to the children of his marriages). His famous grandson wrote a biography of Erasmus and then turned it over to his own daughter, Henrietta, for editing. She cut out about 16% as being too scandalous for a Victorian audience.

Erasmus Darwin proposed that evolution was driven by the environment without, again, proposing any specific mechanism for this. He also proposed that all life on earth had a common ancestor and that animals and plants had evolved from small simple organisms. Dr. Darwin knew his ideas were controversial and waited to publish them late in life. However the advent of the Napoleonic wars caused British society to become more reactionary and his ideas were subject to fierce criticism and ridicule and his reputation suffered considerably for a long time after his death.

Both Buffon and the elder Darwin were imaginative and highly speculative natural historians. They anticipated Darwinian notions by almost a century in some areas and were wildly wrong in others. In the mid to late 18th century, although probably socially more likely to accept evolutionary ideas than the Victorian era, there simply was not enough information available to build a background case. Knowledge from other fields such as geology and economics was necessary.

Uniformatarianism Probably the most important work supporting evolution prior to Darwin was in the field of geology and the development of the idea of Uniformitarianism. This idea was developed in the late 18th Century by Scottish naturalists and came to be quite influential. It was originally developed by James Hutton (1726-1797) and first popularized by John Playfair (1748-1819) in book published in 1802. The idea of uniformitarianism was that the geological structure of the earth was not the result of a single creative act but was the result of many different forces, acting differently in different places and at different times. These forces could be observed acting on earth today. The idea of uniformitarianism was most strongly championed and thoroughly developed by a youthful scholar named Charles Lyell (1797-1875). Lyell's work, The Principles of Geology, was published in multiple volumes from 1830-1833 and really put uniformitarianism on the map.

The central idea, applied by Lyell to rocks, not only has applications to evolution, has parallel logic to that which led Darwin and others to the idea of evolution. Uniformitarianism argues that the past history of the earth can be understood by processes observed in the present day without recourse to other factors. Sedimentary rock is the result of the accumulation of sediment and the application of pressure. Igneous rock is the result of volcanic activity. And so on. An immediate and important implication of uniformitarianism is that the earth is much much older than the few thousand years that was widely believed at the time. No absolute methods for dating rocks existed in the early 19th century and estimates of the age of geological formations varied widely, mostly being much shorter/younger than has been revealed with radiometric dating.

Fossils and Strata An important observation, in light of uniformitarianism, was the presence of fossils. Preserved parts of organisms were commonly found in sedimentary rock. Most of these fossils represented organisms that were not known to the naturalists as living entities. What is more, specific layers of rock usually had characteristic fossils in them. The clear implication of the presence of fossils and the concept of uniformitarianism is that the kinds of life on earth had changed over time.

William 'Strata' Smith (1769-1839) was a surveyor and engineer who came from a humble background and was largely self educated. He worked widely in Britain and developed an interest in geology in general and fossils in particular. His particular contribution was to note that specific layers of rock had characteristic fossils and that these strata could be recognized in disparate parts of Great Britain. The obvious implication of his work is that the types of organisms found on earth have changed in a consistent way over time (fossils are not random but have a definite temporal pattern). He painstakingly prepared a geologic map of Great Britain. Initially this effort was not well received but late in his life Smith did receive recognition for his work.

Mary Anning (1799-1847) came from an impoverished background on the southern coast of England, in an area rich in fossils. Her family made their living, in part, by finding fossils and selling them to scientists. Mary quickly proved highly skilled at locating fossils, being involved in the discovery of the first Ichthyosaurus fossil known to London scholars before reaching her teens! By her early 20s she was running the family fossil business. In addition to her skill at finding fossils she became a talented biological illustrator and knew the taxonomy and anatomy of the fossil organisms as well as scholars in the museums. If she had not had the double disadvantage of being from the lower classes and being a woman she might well have become a recognized scholar in paleontology.

Malthus and the Struggle for Existence Thomas Malthus (1766-1834) was a political economist who pointed out in 1798 that populations of plants and animals always increase unless limited by some external factor and eventually exhaust their resources. Malthus' work was primarily oriented towards human social welfare and argued that limitations on population growth were necessary to avoid poverty and misery. However, his observation that reproduction and population growth led to a struggle for resources proved to be valuable in influencing Darwin and others who independently came to the idea of natural selection. Natural selection is the mechanism driving evolutionary change according to Darwin (today we would describe it as one of several evolutionary forces).

Comparative Anatomy Georges Cuvier (1769-1832) was a very prominent French scholar. Credited as the father of comparative anatomy Cuvier made immense contributions to our understanding of the diversity of animal structure. He performed very detailed studies of the anatomy of many animals and made connections between them. His work emphasized very strongly the link between structure and function and integration of the many parts of organisms into a whole individual.

Ironically Cuvier compiled a massive amount of evidence for evolution while remaining a staunch opponent of evolution. His comparative studies of anatomy provided links that connected many different groups of organisms. Like Buffon he was a pioneer in the study of stratigraphy (layers of rock and their characteristic fossils) and originated the concept of extinction. But he firmly rejected the idea of gradual change in species over time, maintaining that the similarity among species reflecting common needs and that each species had been created in its current form and was immutable. His perception was that each species was such a perfect balance of structure and function across all of its parts that change was impossible. He strongly disagreed with his fellow countrymen Lamarck and Geoffrey and his knowledge and standing made him a formidable opponent. Cuvier felt that the changes in the fossil record over time were the result of recurring catastrophes that wiped out local populations which were replaced by other species moving in from elsewhere.

Richard Owen (1804-1892) was the most prominent figure in British comparative anatomy. Strongly influenced by Cuvier, Owen was a staunch opponent of evolution all of his life. Owen coined the term homology, which today we use to describe structures in different species that have a common evolutionary origin. In Owen's view homologous structures were all derivations from the same universal archetype. Unlike Cuvier he was a contemporary of Darwin. By the time of Owen's death Darwin had been dead for a decade and, except for a few elderly holdouts evolution was accepted by all biologists. Similarly Louis Agassiz (1807-1873) a Swiss-born American biologist was a Catastrophist and fierce opponent of evolution. Agassiz's position was more extreme than either Owen or Cuvier in that he proposed a series of special creations following extinction events to explain the fossil record.

Evolutionary Theories in the Early 19th Century A surprisingly large number of figures proposed evolutionary ideas in the first half of the 19th century. The most well known of these was Jean-Baptiste Lamarck (1744-1829) a very prominent French biologist, who was a pioneer in invertebrate zoology and the first person to use the word biology in the sense we know it today. Lamarck, is somewhat unfairly, most famous today for being wrong. At the turn of the 19th century he proposed that the environment influenced organisms and caused evolutionary change. His ideas differed from natural selection in that he proposed a different link between the environment and evolutionary change. In Lamarck's view the link was the actions of the organism - it's use or disuse of organs.

For example, he proposed that organs that were used would evolve to fit their use. The famous example is the neck of the giraffe. Lamarck proposed that as giraffes stretched their necks to reach food high in trees their necks became slightly longer and this lengthening was passed on to their offspring.

It turns out that, at least most of the time, Lamarck was incorrect about the way in which characteristics are inherited by offspring from their parents. But he was correct in the idea that the environment is the driving force behind evolutionary change, he was just incorrect in the details of inheritance, a problem that would plague evolutionary biology for over a hundred years after his work. Lamarck put forward the most comprehensive hypothesis about biological evolution to date. Unfortunately this made Cuvier his enemy and Lamarck fell into poverty and obscurity. His work was held in low regard even before Darwin's rise to fame.

Étienne Geoffroy Saint-Hilaire (1772-1844) was another French pioneer in evolution. His views might be said to fall somewhere between those of Cuvier and Lamarck. Geoffroy's studies of anatomy led him to believe in a unity of form. Although he did not use the term he was very interested in homologous structures (structures that have the same evolutionary origin) and tried to detect them even in very disparate groups such as insects and vertebrates. Although his primary focus was not evolution he did propose some ideas about possible changes in species due to the environment.

Quite a few British scholars also proposed evolutionary ideas in the early 19th century. William Charles Wells (1757-1817) appears to have been the earliest proponent of what would later be called natural selection. Wells was born in Charleston South Carolina to Scottish parents and educated in Edinburgh. He left the US during the revolutionary war and only returned briefly thereafter, living the rest of his life in Britain. in 1813 Wells proposed natural selection as a mechanism for the evolution of skin color and the formation of human races. Humans with skin coloration that best fit with their environment would be more successful and have more offspring.

Patrick Matthew (1790-1874) was a Scottish agriculturalist who proposed the idea of natural selection in an appendix to a book on the development of naval timber published in 1831. Matthew did not develop the idea to any great extent. After the publication of ''On the Origin of Species' Matthew did come forward and wrote Darwin. Darwin subsequently credited Matthew with his early encapsulation of the idea in later editions of his book. Matthew also apparently credited himself as the 'Discoverer of Natural Selection' on his calling cards

Edward Blyth (1810-1873) was one of the founders of zoology in India (as well as having one of the most impressive examples of Victorian facial hair I've ever seen) and wrote articles in Natural History magazine in 1835-1837 that also summarized natural selection. Unlike Darwin Blyth saw selection largely as a force for maintaining a species in its present form (what we would today call stabilizing selection) rather than causing species to change. Darwin corresponded with Blyth in the 1850s and mentions him in the acknowledgements of the 'Origin'.

Sir William Lawrence (1783-1867)was another English physician who wrote about human evolution in two books during the second decade of the 19th century. He appeared to have a better concept of inheritance than Darwin did decades later but lacked a clear idea of natural selection. Lawrence's books caused intense controversy, to the extent of being labelled blasphemous.

Finally, the book 'Vestiges of the Natural History of Creation' was published anonymously in 1844 (the author was Scottish journalist Robert Chambers). A piece of pop science that combined biological and non-biological evolution into a general theory of transmutation in which the physical phenomena of the universe change over time in accordance with natural laws that do not need continual acts of creation by god. The book was extremely popular in many elements of Victorian society but was roundly condemned by professional scientists and by the religious establishment. Although a much less rigorous work it is likely that 'Vestiges' helped pave the way for the acceptance of the 'Origin'

Summary By the middle of the 19th century biological evolution was a widespread idea. There was strong empirical data that the earth was much older than was proposed by Biblical literalists and also strong data that very different forms of life had lived on the earth in the ancient past. Although a belief in a young earth and the literal truth of biblical creation were the norm among the European population at large, these views were not held by most scientists of the time.

Evolutionary ideas had been proposed by several people but generally they lacked a mechanism to drive evolutionary change or if, in the case of Lamarck, they did propose a mechanism, it was demonstrably incorrect. Malthus' work on populations in conjunction with the applied sciences of medicine and agriculture had lead several scholars to the idea of natural selection but they had not generally linked it to a larger evolutionary view. The scientific world was ready for someone with both the imagination to seize on new ideas and the discipline to synthesize the vast array of supporting information into a coherent theory.

Next time; Part 2: Darwin and Wallace.

Originally posted to matching mole on Tue Feb 07, 2012 at 07:14 PM PST.

Also republished by SciTech and Community Spotlight.

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