Charles Darwin presented the concept of evolution by natural selection to the world in 1859, when he published his classic On the Origin of Species. In honor of Darwin Day (February 12, 2016) I would like to discuss the evolution of (Darwin’s) evolution, and highlight some of the disparate influences in Darwin’s life that led to publication of one of the most powerful ideas in biology.
Evolution per se was not a new idea in Darwin’s time. In the late 1700’s and early 1800’s, several figures in particular developed concepts central to the current view of evolution.
· Georges Cuvier (1744-1829) –The notable natural historian Georges Cuvier (for whom the Cuvier’s beaked whale is named) was the first to establish extinction as a fact. Prior to Cuvier, those who studied fossils assumed that they represented anomalous versions of extant animals, or animals that still lived in other parts of the world. Cuvier found fossils that did not match any living animals, and determined that species did, indeed, go extinct.
· Jean Baptiste Lamarck (1769-1832) – Lamarck studied animals and fossils from around the world. This study led him to the same overall conclusion as Darwin. That is, that species vary over time in response to changes in the environment. With enough time, nature will develop species to fit every environment. He lacked the details to flesh out his ideas, and his theories were attacked by other scientist of the day. However, to Charles Darwin these concepts were so influential that in 1861 he wrote:
Lamarck was the first man whose conclusions on the subject excited much attention. This justly celebrated naturalist first published his views in 1801. . . he first did the eminent service of arousing attention to the probability of all changes in the organic, as well as in the inorganic world, being the result of law, and not of miraculous interposition.
· Erasmus Darwin (1731-1802) – Although Charles Darwin never met his grandfather Erasmus Darwin, he was strongly influenced by his work and read his papers and poetry. Erasmus was a social liberal and a free-thinker. A physician by trade, he refused an invitation by King George III to become the Royal Physician, preferring instead to work with the poor in his community. He promoted social equality, and proposed that women should receive a proper education, including studies in physical education, the sciences, and the arts. His ideas of evolution were so close to those of Lamarck that it’s hard to believe the two never met. He wrote his ideas in both prose and poetry. Yes, he set his evolutionary ideas to rhyme and verse. You can check out some of his poetry at www.poemhunter.com/erasmus-darwin/.
Charles Darwin was himself was born in 1809, the son of a physician. He was expected to become a physician himself, and entered medical school in Edinburgh in 1825. It was in medical school that his father gave him his grandfather’s papers to study, inadvertently exposing him to evolutionary ideas. He found he was too squeamish for the medicine of the day, however, and left medical school in 1827. His real passion was natural history, and in 1828 he enrolled in Christ’s College in Cambridge to pursue a degree in his chosen field. While in school, he spent his extra time hunting and collecting insects. These were skills he would put to good use later in life. He graduated in 1831.
Shortly after graduating, he was offered the position of ship’s naturalist on the HMS Beagle, a Royal Naval ship commissioned to study the biology and geology of South America. Darwin served on the Beagle from 1831 to 1836. The captain of the ship, Robert FitzRoy, introduced Darwin to the work of Charles Lyell, another great influence in Darwin’s life.
· Charles Lyell (1797-1875) – Lyell was a prominent geologist who wrote the book Principles of Geology. In this book, Lyell presented his idea that the world is not static, and that geology is the result of slow, continuous processes. At this time, fossil patterns and large scale geological features were explained largely by biblical events, such Noah’s flood. Lyell proposed instead that these features weren’t based on distinct biblical cataclysms, but on the cumulative effects of well-known processes. This planted in Darwin’s mind the idea that biological processes might also be based on slow cumulative changes, rather than cataclysmic events. In other words, large changes between species didn’t have to occur all at once, but could proceed through a slow series of continuous changes.
While on the Beagle, Darwin collected specimens, fossils, and notes that he would analyze and interpret for years to come. In the years between his return from the Beagle voyage and the publication of Origin of the Species, there were many factors that helped lead Darwin to his conclusions on evolution. This article will only discuss a few of them.
· Thomas Malthus (1766-1834) – In 1798, Malthus published his Essay on the Principle of Population. In this article, Malthus observed that plants and animals produce more offspring than can survive naturally. Humans also have the capacity to overproduce, and left unchecked populations could grow unsustainably. Darwin came across this article in 1838 and applied it to his developing ideas on evolution. He reckoned that if animals produced more offspring than could survive, the offspring that survived should have some advantage over those that didn’t. That is, there had to be some force to determine which offspring lived and which ones died. He called this force natural selection.
· Artificial Selection – There was no way at that time for Darwin to test his ideas. Instead, he turned to the literature on selective breeding of plants and animals. He observed that different breeds of plants and animals could be produced by selectively
|Alfred R. Wallace|
breeding parents most strongly demonstrating the characteristics you want in the offspring. He reckoned that there was some inherent variability for each characteristic available to each generation. By reinforcing desired characteristics by only breeding parents demonstrating that character, you could reduce the variability for that characteristic, thus creating specific breeds with specific characteristics. He coined the term Artificial Selection to distinguish it from Natural Selection, which is the corresponding pressure nature exerts on species to help them adapt to changing conditions.
· Alfred Russel Wallace (1823-1913) – In 1858, Wallace sent a letter to Darwin asking for him to review a manuscript he was preparing on the topic of evolution. As frequently happens in science, he developed a concept of evolution very similar to Darwin’s, and he wanted Darwin to review it and let him know if it was worth publishing. Wallace published his paper in 1858, alongside one of Darwin’s papers. The papers Darwin and Wallace published received little attention from the scientific community, but it was enough to prompt Darwin to write his seminal book, On the Origin of Species.
|On the Origin of Species, Charles Darwin, 1859.|
On the Origin of Species is one of the most influential books in biology, and underpins all modern research in ecology, natural history, medicine, and all other biological fields. As we honor Charles Darwin on this day, I think it’s important to remember that Darwin was not just a natural historian. He integrated ideas from natural history, geology, social economy, and more. The best science is truly an interdisciplinary endeavor!