"Trees as keys, ladders, maps: A revisionist history of early systematic trees" Petter Hellström (Uppsala University, Sweden)

Egenis seminar series. In recent years, there has been a profusion of studies charting the history of tree diagrams in natural history and biological systematics. Whereas some of these have focused on one or a few arboreal schemes, the majority have presented long histories, spanning centuries and occasionally even millennia. Early or ‘pre-Darwinian’ trees typically feature in these histories as precursors to phylogenetics; sometimes even as the ‘roots’ of later trees. Together with colleagues in France, I have previously argued that one of the most frequently cited early tree diagrams, Augustin Augier’s ‘Botanical Tree’ (1801), cannot in any reasonable way be made to play the role of forerunner to later, evolutionary trees—even as the author pitched his tree of natural families in explicitly genealogical terms. In this talk, I push the argument further by proposing an alternative reading of the historical record. Starting from Augier’s tree and other early examples, I argue that ‘pre-evolutionary’ trees should be understood less in terms of what came after, and more in terms of what came before. Attending to the functions they performed as keys, ladders, and maps, I argue that early trees were logical, rhetorical, and mnemonic devices drawn to imagine perfect, static order.