Jacob Suissa joins the Friedman Lab

After earning his undergraduate degree in plant biology from the University of Vermont, Jacob spent time studying the phylogenetics of lycophytes at the Smithsonian Institution’s National Museum of Natural History. As a PhD student in the department of Organismic and Evolutionary Biology, he plans to delve into research focusing on morphological development and diversification in a phylogenetic context.

Welcome Jacob!

Tracing the Evolution of Form and Function

The Arboretum’s 2017 plant anatomy summer short course kicks off at the Weld Hill research facility.

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Denis Diderot

Denis Diderot (1713-1784)

Coming soon.

Franz Unger

Franz Unger (1800-1870)

Franz Unger

Franz Unger was an Austrian botanist, biogeographer, and paleontologist who trained in law, medicine, and natural history before being appointed to the faculty of the University of Graz and director of its botanical garden. He was an early adherent of the “cell theory” (attributed to Schleiden and Schwann) that postulated that all cells in organisms are derived from preexisting cells and that such units are the fundamental building blocks of organisms.

Unger’s pre-Darwinian evolutionary views can be found in a series of books published in the 1850s, including Botanische Briefe (1852) which was translated into English Botanical Letters (1853), Versuch einer Geschichte der Pflanzenwelt (1852), and his popular illustrated treatment of the primeval world Die Urwelt in ihren verschiedenen Bildungsperioden (1851; see Rudwick, 1992 for reproductions of illustrations). Unger stressed that just as there was continuity of cells and cell lineage, that organisms gave birth to other organisms, the same is true of species, which must arise from previously existing species (as opposed to miraculous or spontaneous generation). In essence, Unger gave species the attributes of an ontogeny, with a birth, period of development, and finally extinction. Unger also viewed species and varieties as part of a continuum.  Ironically, after publication of On the Origin of Species, Unger rejected the mechanism of natural selection, as this would necessitate the evolution of the human mind. Unger was no materialist.

With respect to plants, Unger hypothesized that the origin of plant life could be traced to a single cell: “In short, the cell is not only the starting point of the individual life of the plant, but at the same time the starting point of the life of species and all higher unities; it is indeed likewise the starting point of the whole plant world.” Unger’s understanding of the fossil history of plants was used to argue that “the world of plants also, which is divided into seven great geological periods (including the present one), has gradually developed itself step by step.” Finally, Unger also noted that deviant forms of plants (sports) could give rise to new varieties and that such deviations were not the result of external (environmental) influences, but rather something more fundamental that can “transmute also one species into another.”

For an article on Unger and his evolutionism, see Gliboff (1998): Evolution, revolution, and reform in Vienna: Franz Unger’s ideas on descent and their post-1848 reception. Journal of the History of Biology 31: 179-209.

A Calamite Forest of the Coal Period

A Calamite Forest of the Coal Period

Charles Southwell

Charles Southwell (1814-1860)

Charles Southwell’s atheistical publication The Oracle of Reason, or Philosophy Vindicated is a primary example of the manner in which transformist ideas of the Victorian period could be co-opted and made to serve political, social, or philosophical aims. Southwell, the youngest of 33 children from a working-class English family, was a radical freethinker, social reformer, and an atheist. In 1841 he founded The Oracle of Reason along with William Chilton and John Field, and became the first editor of the periodical. In a 48-part series of short articles in the Oracle entitled Theory of Regular Gradation, Southwell drew on contemporary ideas of progressive evolution to further a materialistic and anti-religious worldview.

The series is heralded by a crude illustration of the French naturalist Pierre Boitard’s “L’Homme Fossile” and an accompanying quote from Boitard encapsulating the thesis of regular gradation: “…organic formation after organic formation has taken place, passing gradually from simple to compound bodies…”. Southwell then describes the clerical opposition to viewing man as having any relation to “the inferior animals”, denouncing those who “rest contented in most shameful ignorance, rather than their pride should be mortified by any discoveries in science, hostile to their cherished opinions” (I). Not a naturalist himself, Southwell attributed the scientific “facts” in his publication to an eclectic selection of naturalists-from the less reputable science of Boitard and Lord Monboddo to the more esteemed Buffon and Lamarck. (The Oracle’s co-founder, William Chilton, who would write the later articles in the Theory of Regular Gradation, drew more heavily upon Lamarck and Lyell.) Progressive evolution, Southwell claimed, proved that “there are no fixed modes (laws as they are styled) for each species and each part, there being nothing fixed in the parts of nature, which are in a continual state of flux or change (III).

Transmutation was helpful to the reformer and the atheist agenda not only because it debunked the theory of special creation, but also because it seemed to indicate a sort of fluidity in nature – a lack of any true distinction among natural kinds – which aided Southwell and his peers in portraying the existing hierarchical religious and social structure as having been arbitrarily imposed on the natural world by an aristocratic elite anxious to maintain the status quo. In the Theory of Regular Gradation, Southwell was particularly devoted to teaching his readers about Boitard’s “oscillatoires de murailles” – ambiguous simple-celled forms of life which were difficult to classify as belonging to either the plant or animal kingdom. His writing makes evident that he saw in this ambiguity in nature, support for a materialist, reductionist view of the world which made it possible to denounce both the existing social structure and traditional Christian teaching.

In fact, whereas other reformers of the period accepted at least a nominal association with Protestant Christianity for the sake of achieving their goals of social reform, Southwell had a particular virulence toward the Church of England and for this reason had broken from the socialist missionary group founded by Robert Owen before founding The Oracle. Ultimately, his denunciation of religion in The Oracle (he used particularly racist and offensive terms in his descriptions of the Bible) led to his arrest and imprisonment for blasphemy. As a result, William Chilton assumed authorship of the Theory of Regular Gradation series, picking up where Southwell left off after the sixth article. Eventually, The Oracle shut down in 1843 due to financial difficulties.

For a more in-depth treatment of Southwell’s use of evolutionary biology in the sociopolitical context of Victorian England, please see Adrian Desmond’s Artisan Resistance and Evolution in Britain, 1819-1848 and Beyond the ‘Common Context’: The Production and Reading of the Bridgewater Treatises by Jonathan Topham.

Constantine Rafinesque (1738-1840)

Constantine Rafinesque (1783-1840)

The truth is that Species and perhaps Genera also, are forming in organized beings by gradual deviations of shapes, forms and organs, taking place in the lapse of time. There is a tendency to deviations and mutations through plants and animals by gradual steps at remote irregular periods. This is a part of the great universal law of PERPETUAL MUTABILITY in everything. Thus it is needless to dispute and differ about new G. [genera] Sp. [species] and varieties. Every variety is a deviation which becomes a Sp. As soon as it is permanent by reproduction. Deviations in essential organs may thus gradually become new G.” (Rafinesque, “Principle of the Philosophy of New Genera and New Species of Plants and Animals”, 1833).

In 1841, the American botanist Asa Gray authored a “Notice of the Botanical Writings of the Late C.S. Rafinesque.” Regrettably for Rafinesque, Gray was no fan of his voluminous additions to the number of plant taxa that were previously recognized as species by botanists.  In his lifetime, Rafinesque would go on to name more plant species than even Linnaeus.  Gray wrote,  “According to his principles, this business of establishing new genera and species will be endless; for he insists… that both new species and new genera are continually produced by the deviation of existing forms, which at length give rise to new species… He assumes thirty to one hundred years as the average time required for the production of a new species, and five hundred to one thousand years for a new genus… (238, American Journal of Science and the Arts, 1841).

Rafinesque’s ideas on the variation of botanical form were inseparable from both his evolutionary theory and his botanical methods. In 1833, he published, “Principle of the Philosophy of New Genera and New Species of Plants and Animals”, containing excerpts of a letter he had written to the botanist John Torrey, in his own Atlantic Journal, and Friend of Knowledge to advance his opinions that recognition of the “great universal law of Perpetual mutability” implied a change in classificatory practice among professional botanists. He proposed that the “tendency to deviations and mutations through plants and animals by gradual steps at remote irregular periods” would allow observers of the natural world to trace each species or variety back to its primitive original, therefore creating a new “natural” genealogical method of classification and condensing and simplifying extant classificatory systems (1833, 1836).

If it is inescapably true that in every small variant of nature, Rafinesque saw the potential makings of a new species, it is also true that this world view represented the antithesis of the dominant views of most classifiers and taxonomists, who insisted – at least for purposes of their science – that species were eternally unchanging. “Nature only acknowledges individuals, and varies them constantly; so as to produce new species now and then…” (The World, 1836) Rafinesque had a keen awareness of variation within species, and understood that such variation was the raw material of evolution.

“The process is by the seedlings being somewhat different from the parents, and thus evincing a deviation of typical mould, that may be, or may not be; propagated again. If it is, this soon assumes a permanence, becoming a permanent variety if the deviation is slight, such as mere color of flowers, size of stem, leaves, &c.; but becoming a New Species! if at last several deviations are permanently combined. A tendency to such deviations is sometimes met even in the various annual shoots of the perennial plants, or shrubs and trees, that are not always alike to those of the preceding years.” (16, New Flora and Botany of North America, 1836)

What is clear in Rafinesque’s transmutationist writings is that he did not view all of life as descended from a single common ancestor. “All species may have been varieties once, except the original types or ancestors of the genus…”; a failing that was noted in Darwin’s Historical Sketch. Thus, in a manner reminiscent of the eminent plant hybridizer William Herbert, Rafinesque could envision the evolution of new species but could not imagine scaling this common process to all of life.

“We know not how many living forms existed at first, or were created on earth at the earliest period; but by the fossil relics of many, we ascertain that they were fewer and often different. Whatever was their original number and types; it is probable that these primitive individuals have produced all the actual various species, of which we have already ascertained nearly eighty thousand of animals, with a hundred and twenty thousand of plants. The proofs of this fact are found in the varieties and monstruosities, still proceeding under our eyes, or that have for ages past. Every species was once a variety, and every variety is the embryo of a new species.” (The World, 1836)

Also like Herbert, Rafinesque wrote a lengthy poem that included the topic of mutability in the natural world. In The World, or Instability (1836), his ideas on evolution in nature are placed in the context of his philosophical view of a Hericlitean world. This poem also strongly echoes Erasmus Darwin’s posthumously published Temple of Nature (1803).  Advocating for an eternal law of constant change which causes deviations in the form of living beings, including plants, he writes:

“…CHANGE extends also to vary forms,

…Not even two leaves or blooms

In vain you’ll seek to match upon a tree.

…This is the Law, the positive decree…” (14-15, Worlds, 1836).

Complicating Rafinesque’s supposedly simpler method of classification was the fact that he believed each new form should be given a new name. This propensity for “multiply[ing] names” upset many of his botanical contemporaries who, like Gray, disregarded much of Rafinesque’s work during his lifetime. Nevertheless, Rafinesque’s existing publications show him to have been a polyglot who published on a multitude of topics including botany, zoology, and linguistics. Despite being denied a position on the Lewis and Clark expedition of 1806, Rafinesque individually surveyed much of the southern and central North American flora. He was appointed a professorship at Transylvanian University in Kentucky in 1819, but left over disagreements with the administration.

Lorenz Oken

Lorenz Oken (1779-1851)

Coming soon.