Joseph LeConte (February 26, 1823 – July 6, 1901), American geologist, conservationist, and professor at UC Berkeley, made significant contributions to the science of geology following the era of Charles Lyell and Charles Darwin. Importantly, this represents the major shift in scientific thought towards the principle of Uniformitarianism – that the natural processes we observe today have been in effect on the Earth for millennia. This allowed for scientists to make inferences about past events based on their knowledge and observations of current events, or events and processes described by other scientists. It is for this reason I’ve decided to review as much as possible of LeConte’s major work on geology – “The Elements of Geology” – in an attempt to understand 1.) how the science of geology has changed over the past 120 years since the book’s inception and 2.) understand, in general, how scientific thinking has changed over the past century. How did professor’s and scientists formulate arguments, describe complex ideas, develop new theories, and present evidence in age where the computer had not yet been invented? Hopefully this series of posts will shed some light on how scientific thinking and communication strategies have changed over the course of human development.
LeConte begins the Elements with a brief introductory chapter introducing his framework for the study of geology. Here, LeConte outlines the 3 principal departments of geology by using analogies to organic science – what we might today call the life sciences or biological sciences. He relates structural geology to the study of anatomy, dynamical or chemical geology to the study of physiology, and historical geology to the study of embryology or developmental biology. Interestingly though, in the following half of his introduction, he highlights a key difference between the two sciences.
But there are two important points of difference between geology and organic science. The central department of organic science is physiology, and both anatomy and embryology are chiefly studied to throw light on this. But the central department of geology, to which the others are subservient, is history. Again : in case of organisms – especially animal organisms – the nature of the changes producing development is such that the record of each previous condition is successively and entirely obliterated ; so that the science of embryology is possible only by direct observation of each successive stage. If this were true also of the earth, a history of the earth would, of course, be impossible. But, fortunately, we find that each previous condition of the earth has left its record indelibly impressed on its structure.
Elements of Geology, pg. 2, Joseph LeConte, D. Appleton and Company, 1896
Namely, LeConte emphasizes that the central tenet of the organic sciences (biology) is the understanding of physiology through the lenses of anatomy and embryology. Conversely, he states that the central tenet of geology is historical geology (the organic equivalent being embryology), and that the history of the earth can only be studied through the lenses of structural and dynamical geology. Interestingly, LeConte alludes here to a principal that might have been known at the time, but the specific mechanism largely a mystery – that biological organisms selectively kill of cells and tissue during various stages of embryonic development, or even post-embryonic, through specific biochemical pathways that have evolved to activate at specific times during an organisms life cycle. In this way, LeConte is correct – biology tends to eliminate its past completely through selective pruning, whereas geology has no pruning mechanism (save, perhaps, volcanic processes). In other words, in LeConte’s view, geological processes tend to preserve more historical information than organic ones.
Furthermore, another interesting faucet of science is touched on in this passage. Famously, Ernst Haeckel wrongly concluded from his embryological observations that “Ontology recapitulates phylogeny”. That is, the entire evolutionary history of an organism is played out during the embryological development of an organism (e.g., from fish to vertebrate in the development of a human fetus). This was later shown to be an incorrect conclusion as it was shown that developmental processes only retain traits or phases as they are relevant to the evolutionary fitness of an organism, and so the presence or absence of developmental phases (e.g., a “fish” phase or a “tail” phase) during embryological development reflects the steps needed to produce a healthy, functioning organism rather than specifically retaining each step of organism’s evolution in development. That is to say, entire phases of embryological development might be lost or gained regardless of evolutionary history.
Part of the thinking that led to the widespread belief that “Ontology recapitulated phylogeny” went in line with the tendency for early scientific thinkers to occasionally, or frequently, embrace teleological thinking – the process of describing scientific processes in terms of their apparent goal – which led to the anthropomorphical description of many processes later shown to be undirected (e.g., Darwinian selection and dynamical geological processes). Interestingly, LeConte’s statement that organic processes obliterate information, seems to directly contradict the idea that evolutionary history reflected during embryonic development, making him a possible early-adopter of the more rigorous Darwinian lines of thinking regarding the type of information that embryonic development actually portrays.
In concluding his introduction, LeConte describes the prime objective of geology “as the history of the earth and its inhabitants, as revealed in its structure, and as interpreted by causes still in operation”. This is an interesting “prime objective” of geology and it might find itself at odds with modern interpretations of the geological sciences. Although the study of the history of broad patterns in life and macroevolution are still relegated to geology in that tend to pertain to the major geological epoch’s described in earth’s history, the majority of specific scientific understandings for the “inhabitants” of earth have shifted into their own sciences: paleontology (the study of extinct organisms) and neontology (the study of extant, still living organisms). In this sense, modern students of geology may be confused by LeConte’s introduction and find it strange to learn that they are about to have indepth discussions regarding the evolutionary history of life on earth, but LeConte might respond that the two budding sciences are still deeply intertwined and so should be studied together.
Next up will be LeConte’s introduction to Dynamical Geology – the science of the active processes of geology as they can be observed in modern times. Stay tuned!