On this date, America’s leading botanist in the mid-nineteenth century, Asa Gray, was born. On a visit to England in 1851, Gray met for lunch with Charles Darwin, and they formed a lasting connection. When Gray returned to the United States, he was able to see that North American plant life had evolved under the disruption of the ice age. In a famous letterto Gray dated September 5, 1857, Darwin wrote:
As you seem interested in subject, & as it is an immense advantage to me to write to you & to hear ever so briefly, what you think, I will enclose (copied so as to save you trouble in reading) the briefest abstract of my notions on the means by which nature makes her species. Why I think that species have really changed depends on general facts in the affinities, embryology, rudimentary organs, geological history & geographical distribution of organic beings. In regard to my abstract you must take immensely on trust; each paragraph occupying one or two chapters in my Book. You will, perhaps, think it paltry in me, when I ask you not to mention my doctrine; the reason is, if anyone, like the Author of the Vestiges, were to hear of them, he might easily work them in, & then I shd’have to quote from a work perhaps despised by naturalists & this would greatly injure any chance of my views being received by those alone whose opinion I value.—…
Gray was the third scientist Darwin told of his theory (after Hooker and Lyell). [Less than a year later, both Darwin and Wallace publicly proposed that evolution occurred by natural selection. It was Darwin's good luck that his early correspondence with Gray showed that he had been first to articulate the idea.] The depth of their friendship was evident in a letter dated January 23, 1860 concerning the help the American botanist wished to give Darwin in presenting his book to the American public. In this letter Gray wrote:
Your candor is worth everything to your cause. It is refreshing to find a person with a new theory who frankly confesses that he finds difficulties, insurmountable at least for the present. I know some people who never have any difficulties to speak of. The moment I understood your premises I felt sure you had real foundation to hold on. Well, if one admits the premises, I do not see how it is to stop short of your conclusions, as a probable hypothesis, at least.
In 1856, Gray published a paper on the distribution of plants under the title Statistics of the Flora of the Northern United States; and this paper was followed in 1859 by a memoir on the botany of Japan and its relations to that of North America, a paper of which Sir J. D. Hooker said that “in point of originality and far-reaching results [it] was its author’s opus magnum.” Gray’s discovery of close affinities between East Asian and North American floras was a key piece of evidence in favor of evolution. He explained this disjunct distribution pattern by suggesting that New England and temperate Asia had once been geographically continuous and had had a uniform flora which only diverged after the areas were separated by later geological events. This hypothesis has not only held up, supported by the discovery of continental drift and plate tectonics, it has also proved fruitful enough to provide a basis for current and important research in vicariance biogeography.
From 1855 to 1875, Gray was both a keen critic and a sympathetic exponent of Darwin’s theory of evolution. His religious views were those of the Evangelical bodies in the Protestant Church; so that, when Darwinism was attacked as equivalent to atheism, he was in position to answer effectively the unfounded allegation that it was fatal to the doctrine of design. He openly avowed his conviction that the present species are not special creations, but rather derived from previously existing species; and he made his avowal with frank courage, when this truth was scarcely recognized by any naturalists, and when to the clerical mind evolution meant atheism. The Rev. R. W. Church, the Dean of St. Paul, had met Gray in 1853 and later wrote about his life-long friend:
His religious views were a most characteristic part of the man, and the serious and earnest conviction with which he let them be known had, I am convinced, a most wholesome effect on the development of the great scientific theory in which he was so much interested. It took off a great deal of the theological edge, which was its danger, both to those who upheld and those who opposed it. I am sure things would have gone more crossly and unreasonably if his combination of fearless religion and clearness of mind and wise love of truth had not told in the controversy.
Gray wrote numerous botanical textbooks and works on North American flora, including Flora of North America that he co-authored with his mentor John Torrey.
- Charles Darwin, letter to Asa Gray, September 5, 1857; Reprinted in Frederick Burkhardt, ed., Charles Darwin’s Letters: A Selection 1825-1859 (New York: Cambridge University Press, 1996) 177-179.
- “New Publications; Asa Gray’s Life and Letters: Letters of Asa Gray,” The New York Times (Wednesday, November 19, 1893) 23.