William Herbert (1778-1847)
It was perhaps part of the wise scheme of Providence, for the purpose of peopling the world with the immense diversity of form that occupy it, to give each created race a disposition to branch into diversities, acquiring constitutional particularities, which should keep them more or less separated… (On crosses and hybrid intermixtures in vegetables)
William Herbert was an accomplished scholar, poet, plant hybridizer, and Church of England clergyman who eventually rose to the position of Dean of Manchester. Charles Darwin referred to Herbert as “the third greatest Hybridiser who ever lived.” And indeed, Herbert’s evolutionary view of the world was largely informed by his plant-breeding work.
In 1822, Herbert wrote a seminal paper on the evolution of the constituent species of plant genera from a common ancestor. This paper, “On the Production of Hybrid Vegetables” is extraordinarily forward-thinking and uses the results of hybridization experiments between species as a basis for creating an essentially biosystematic concept of plant relationships. Herbert inferred that the ability of two species to hybridize must be evidence of evolutionary relationship and descent from a common ancestor. He wrote “If it is meant only that fertile offspring may be supposed to intimate, that the two parent plants have branched out from one common stock since the creation of the world, I am fully disposed to admit the truth of that position; but I should go much further, considering that many species…have also descended from one original…” (16). He would go on to define a genus as “all the species which have peculiar affinities, distinguishing them from all others; and which, I think, render it probable that they have branched, since the creation of the world, from one original” (21).
While Herbert was clearly an evolutionist who believed in descent with modification, he was also a creationist who thought that “in the early periods of the world, there existed
only the distinct genera of plants, or heads of families… The lapse of centuries and diversity of soil and climate have probably wrought the most wide and permanent distinctions between vegetables, that have originated from a common stock“ (16, 1822). These ideas would be reiterated in his seminal book Amaryllidaceae (1837), as well as in two papers – “Local Habitation and Wants of Plants” and “On Hybridization amongst Vegetables” published in the Journal of the Horticultural Society of London in 1846 and 1847, respectively.” Darwin wrote to Joseph Hooker about these two papers of Herbert “whose writing I always like.” Herbert’s final thoughts on evolution, and his frustration with biblical literalists, appear in a poem (with an extensive footnote) in 1846 entitled “The Christian,” where Herbert maintained his ultimately hybrid view of the roots of biodiveristy:
[I]n the six great days or periods God created all that is, but not all the precise forms that are now visible. He created the material globe, vegetables, fish, reptiles, insects, birds, quadrupeds, and man; but we have no information as to the manner in which he arranged that such creations should be diversified, as to suit the gradually improving qualities of the world they were to inhabit. He may have impressed upon them a principle of change and development, by which it was pre-ordained that their posterity should become ultimately as different as the from becomes in a short space of time from the tadpole, or the butterfly from the caterpillar…
Herbert’s masterful book on Amaryllidaceae influenced Charles Darwin’s research into evolution in the botanical world. References to Amaryllidaceae are found in Darwin’s Notebook E, and Herbert’s evolutionary ideas are noted in the “Historical Sketch” of the third and subsequent editions of On the Origin of Species. There, Darwin wrote of Herbert: “The Dean believes that single species of each genus were created in an originally highly plastic condition, and that these have produced, chiefly by intercrossing, but likewise by variation, all our existing species.” Amaryllidaceae was by no means Darwin’s only point of contact with Herbert’s work. There was, in fact, a history of communication between Darwin and the Dean of Manchester. In April 1839, Darwin sent a list of questions to Herbert, through their mutual acquaintance and Darwin’s former Cambridge professor, John Stevens Henslow. Most notably, Darwin inquires as to whether Herbert’s crossing experiments led him to notice “any relation between a facility in varying…and a facility in giving hybrids, and especially fertile hybrids.” (Herbert responded to this question in the negative, citing the example of crocuses, which he found difficult to hybridize despite the many varieties known to exist.)
Perhaps is it fitting that one of the last, if not the very last, person to see William Herbert before he died (suddenly), was Charles Darwin himself. As Darwin wrote to Joseph Hooker on June 2, 1847, “I saw the poor old Dean of Manchester on Friday & he received me very kindly: he looked dreadfully ill & about an hour afterward died! I am most sincerely sorry for it.”