Evolution of Evolution — Text-only | Flash Special Report
Evolution A Starry Archetype
Astronomers adapted Darwinism to create organizational framework that describes cosmic evolution
By Dr. David DeVorkin
Strictly speaking, mainstream 19th and early 20th century astronomers were less influenced by Darwinism than they were a part of a larger movement to think in terms of evolutionary change or "universal evolution." For astronomers, this meant that systems of planets and stars, and stars and planets themselves, were not static over time, but changed through gravitational processes, the conversion of gravitational potential into motion, light and heat. It was French mathematician and astronomer Pièrre Simon Laplace's Nebular Hypothesis that galvanized 19th-century thinking, especially in the United States, where the term evolution was quickly appropriated to mean evidence of change in the heavens: of planets, stars and systems of stars. If Darwinism was linked to astronomical progress, it was more than not derided; in 1871 one writer scoffed at the very idea that life existed on the Earth at a time when, according to Laplace, the Earth was still in nebular condensation. Objections to Darwinism then and for the next few decades, indeed dealt with time scales more than anything else as Joe D. Burchfield and others have examined.
By the late 19th Century, it was George Darwin, not Charles, who offered inspiration to American astronomers. Darwin's second son and fifth child explored tidal evolution of rotating fluid masses, i.e. stars and planets. His teachings regarding the high and low tides of the Earth’s solid body, which are very similar to the oceans’ high and low tides, informed all subsequent generations about the planet’s dynamism. Princeton University astronomer Charles A. Young observed in 1884 that George Darwin's theory of tidal evolution "opened a new field of research, and shown the way to new dominions." Not only did it shed light on the dynamical history of the Earth-Moon system, but, Young implied, it offered a new way to organize research.
For Young, and contemporary Victorian astronomers like Norman Lockyer, the English scientist and astronomer who discovered helium and founded the science journal Nature, universal evolution included studying how the very elements of physical existence formed and grew and could be destroyed during the life cycles of stars. Young encouraged his most illustrious student, Henry Norris Russell, to think in evolutionary terms and hold a naturalistic view of the universe, one of continuous development, presently acting and not confined to original cause. These elements indicate Darwinian thinking. Russell’s research, leading to the Hertzsprung-Russell Diagram, the primary descriptive playing field for 20th century stellar astrophysics, was indeed stimulated by a neo-Lockyerian theory of stellar evolution.
A contemporary of Russell's who played possibly the most visible role in America establishing evolutionary thought as the organizing principle for research in astronomy was George Ellery Hale. The driving force behind the establishment of Yerkes Observatory, operated by the University of Chicago in Williams Bay, Wis., one of his first major programs there was to study red stars in the hope that they would lead finally to a “systematic scheme of stellar evolution on spectroscopic observations…” Hale made the observation in Yerkes's Decennial Publications in 1903.
Evolution as Hale understood and expressed it was not Darwinian, but he appropriated Darwinism as a symbol and as an organizing principle. In 1902, he told a popular audience that: "It would be difficult to overestimate the effect which the doctrine of evolution has wrought. The principle of orderly and harmonious development which it embodies has found application, not only in explaining the wide diversity of organic species, but in unifying the events of history, in elucidating the origin of language, and in throwing light on difficult questions in every department of human knowledge."
Over the next decade, Hale used the National Academy of Sciences as a platform to explore what all the sciences could say about the evolution of matter, stars, planets, life, man and society. Among Americans of the intellectual generation following Hale and Russell, leading into the mid-twentieth century, possibly the most ardent proponent of Darwinism—in the manner Hale expressed it—was Russell's former student, Harvard College Observatory director Harlow Shapley, who, unlike the majority of his contemporaries, included biological thinking in his essays on cosmic evolution. As historians have noted, Shapley's 1958 book "Of Stars and Men," a collection of earlier essays and lectures, set the stage for modern American writers—from Sagan to Chaisson—to explore the rich rhetorical landscape made so compelling by Charles Darwin, indeed a popular symbol and organizing principle of modern astronomy.
Dr. David DeVorkin is senior curator of history of astronomy and space sciences at the Smithsonian National Air and Space Museum in Washington, D.C. He is the author/editor/compiler of nine books and more than 100 scholarly and popular articles including “Hubble: Imaging Space and Time” (2008);“Beyond Earth: Mapping the Universe”; “Henry Norris Russell: Dean of American Astronomers”; and “The American Astronomical Society's First Century.”
Please see the Resources section for the Bibliography/Additional Reading list for this essay.