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Mainstream, VOL 62 No 21, May 25, 2024

Marais’s Review of An Introduction to the History of Chronobiology by Jole Shackelford

Saturday 25 May 2024

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BOOK REVIEW

An Introduction to the History of Chronobiology, Volume 1: Biological Rhythms Emerge as a Subject of Scientific Research

by Jole Shackelford

University of Pittsburgh Press
2022. 332 pp.
(cloth), ISBN 978-0-8229-4732-5

Reviewed by Johanné Marais

If you are not yet thinking of the cyclical nature in everything, you may want to pick up Jole Shackelford’s An Introduction to the History of Chronobiology, Volume 1: Biological Rhythms Emerge as a Subject of Scientific Research. In this volume, Shackelford affords the reader a rich, descriptive chronology of the study of biological rhythms, focusing on the lively patterns observed in plants, with extensive elaboration on the scientific dialogues as they surfaced in time.

As the reader follows the rigorous works of renowned scientific thinkers—particularly, those who had a green thumb—one cannot disentangle philosophies of science from scientific inquiry in early rhythms-research processes. Unpacking historical disputes and agreements between teams of scientists from the 1500s to late 1990s, Shackelford exposes the roots of philosophies of science, which informed research questions on the endogenous and exogenous rhythms of living organisms.

Philosophy is densely contained within the history of chronobiology. For those not philosophically inclined, one can become a little overwhelmed by complex terminology like vitalism, reductionism, or behaviorism. If you are not familiar with philosophies of life, I would recommend having a notebook on hand. To put it simply: vitalism operated on a notion that the command of cyclical biological processes (for example, periods of sleep and wake) were occurring from within a plant’s essence; this is endogenous, meaning to occur internally. In contrast, through physicochemical reductionism—minimizing a process to its physics and chemistry—material-mechanical philosophy posits how laws of physics and external prompts command a plant’s behavior; this is exogenous, meaning to occur externally. Behaviors were measured from irritant and response dynamics. I offer the sunflower as an example: cellular or systemic sensing of darkness occurs as irritant, and a dipping of the flower’s head follows as response. Vitalists say that the plant decides; material-mechanists say the environment decides.

Following detailed, factual storytelling (that perhaps only a historian of science is capable of) Shackelford provides concise, procedural demarcations of how a field of knowledge develops to study how plant cycles shift about a calendar day. I will digest some hallmarks here, though I implore that you pick up this book to chew on your own bites too. Shackelford offers the idea that a lore of chronobiology existed before the field was firmly established. Ancient ( 500 CE) cosmological intuitions of an innate universal timing in orbits of planets informed late Renaissance astronomers like Tycho Brahe imagining rhythmicity in nature to be a “microcosmic-macrocosmic correspondence” (p. 29). Already the seed was planted to query what was occurring inherently and what was governed by the external environment.

Over the next 150 years, as Shackleford details, plant physiologists would tamper with cycles of light, nutrients, watering, and temperature to understand the endogenous nature of plant growth and behaviors. Plants grown in complete darkness displaying behavioral periods of “wake” and “sleep” were already noted by astronomer Jean Jacques d’Ortous de Mairan in the early eighteenth century. De Mairan’s friend in the botanical field, Jean Marchant, later amplified this observation as pertinent to the field of biological rhythms rather than astronomy, suggesting that perhaps earlier intuitions that biological rhythms in plants have innate timing were correct (“Observation Botanique,” 1729).

Swedish scientist Carolus Linnaeus recorded observation of plant movements to occur diurnally, which is to say, with a strict twenty-four-hour light/dark cycle (Philosophia Botanique, 1751). Some fifty years later, Kurt Sprengel and Augustin Pyramus de Candolle stood by the idea that nighttime behavioral patterns were intrinsically controlled by the plant, with the sun as a stimulus (Elements of the Philosophy of Plants, 1821). The pair pressed the importance of understanding the natural laws governing plant growth and differentiation. This was a supplement to investigating the chemical composition of plants (phytochemistry) or plant anatomy (de Candolle, Physiologie végétale, 1832). Phytonomy as an area of botanical research seems to have sprouted all over the globe, from small islands in the Atlantic Ocean to remote Scandinavian regions and Germany.

Near the close of the nineteenth century, chronobiology—still not under this name—continued to be understood as an inherited responsiveness subjected to environmental cues. Some foundational “pre-chronobiologists” took on a relatively novel philosophical approach called vital mechanism. Here, researchers such as Wilhelm Pfeffer, Julius Sachs, Dorothea Pertz, and Francis Darwin began reimagining the field as a union between previous philosophical approaches. At this time, attributing vital mechanisms to plant behavior laid the foundation for what is currently understood as homeostasis: cellular programming that integrates environmental cues. After 1915, Pfeffer’s analogy of biological systems as living clocks that move about an endogenous day/night periodicity built acclaim (and resistance) (Beiträge Zur Kenntnis der Entstehung Der Schlafbewegungen). A mysterious, atmospheric “Faktor X,” searched for by scientists like Rose Stoppel (“Die Abhängigkeit der Schlafbewegungen von Phaseolus multiflorus von verschiedenden Außenfaktoren,” 1916) and Erwin Bünning and colleagues, was thought to impart some quality of environmental control on biological rhythms. Despite having intended to help look for Faktor X, Bünning stumbled instead upon observations that confirmed an autonomous rhythm in 1931 (“Untersuchungen über die autonomen tagesperiodischen Bewegungen der Primärblätter von Phaseolus multiflorus”).Through refined phytonomy, Bünning discovered that temperature plays a more important role in changing rhythms than light, while light acts as a factor which triggers the cycle.

Yet, akin to clocks that lose time, so did the cyclical nature of plant behaviors appear to do. Antonia Kleinhoonte elaborated on Pfeffer’s work, confirming his suspicions that plants have a “free-running” period, which is not exactly diurnal (twenty-four hours) but rather around twenty-two to twenty-six hours (“Untersuchungen über die autonomen Bewegungen der Primärblätter von Canavalia ensiformis DC,” 1931-32). Franz Halberg—a godfather of rhythms research—coined the term circadian in 1959 to describe biological rhythmicity to be about (circa-) a twenty-four-hour day (-diem).[1]

Near the close of this volume, Shackleford introduces the term photoperiodicity as an extension of Bünning’s work. Photoperiodicity refers to how packages of light, or photons, influence biological periods. Shackleford expands on this to include how hormones and physiological demands like hunger and sleepiness became of interest to the field of chronobiology—finally called by its name by Halberg in 1969.

One can easily imagine the decades when print publication kindled a greater sense of excitability among researchers of rhythmicity, most of whom waited months or years with eagerness to read or hear of colleagues’ progress in the field of chronobiology. With the urgency of the twenty-first century, a growing attention economy, and an apparent fallowing of integral philosophies of science, I can’t help but wonder whether at least some of the advents of modern chronobiology are lost on its consumers. Does the humble scientist too quickly publish their findings, and is the trend of publish-or-perish detrimental to the romantic quest for knowledge that sprouted chronobiology throughout the last five hundred years?

Perhaps in Shackelford’s volumes that follow, new knowledge may challenge this philosophical thought. For now, you may find me swooning over decade-long experiments in a temperature and light-controlled plant grow room, observing the gentle rise and fall of their petalled heads to pass time.

Note

[1]. Franz Halberg, Erna Halberg, Cyrus P. Barnum, and John J. Bittner, “Physiologic 24-Hour Periodicity in Human Beings and Mice, the Lighting Regimen and Daily Routine,” in Photoperiodism and Related Phenomena in Plants and Animals, Proceedings of the Conference on Photoperiodism, Gatlinburg, TN, October 29-November 2, 1957, ed. Robert B. Withrow (Washington, DC: American Association for the Advancement of Science, 1959), 803–88.

(Review author: Johanné Marais, University of the Witwatersrand)

[This work from H-Net is reproduced under a Creative Commons License]

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