An important part of science education and communication is how scientists draw inferences about the past, but such inferences can also provoke controversy in public forums and in classrooms. Chemistry, told as a narrative thread running through natural history, can unify the complexities of environmental food, energy, and water by describing how the elements work. This narrative can help communicate recent findings about the interactions between the environment and evolving life. (I described this story in the book A World from Dust.) The chemistry of the environment can help give multidisciplinary, narrative explanations in three contentious areas: 1.) Evolution: Oxygen and water interacted to impose a chemical narrative on the planet’s evolving life. The geologist Robert Hazen’s concept of “mineral evolution” on different planets highlights the role of the changing environment as life evolved over billions of years. Oxygen changed the environment and changed concentrations of redox-sensitive transition metals important to life in a chemically predictable pattern, which in turn shaped the evolution of life. These stories nuance discussions of the predictability of evolution by providing a chemical perspective highlighting the importance of the environment. 2.) Origin of life: To the public, laboratory experiments are more convincing than speculative theories. Laboratory experiments have successfully recreated specific, complex biomolecules (such as nucleotides or pyruvate) from simple precursors, often when the conditions mimicked the anoxic, reducing environment of the ancient earth. These show how a complex, cycling environment catalyzes complex biochemical structures. 3.) Climate history: Hazen’s idea that even minerals can evolve leads to the idea that the environment may co-evolve with life. The mechanisms by which this interaction helped the planet retain a liquid phase despite the faint young sun have been described by Chopra and Lineweaver as a “Gaian Bottleneck” for life. Thinking about this hypothesis helps to show how microbial life changed the atmospheric chemistry and therefore the temperature of the planet, making the current human ability to do so more plausible to the public. These narratives combine astronomy, geology, chemistry, and biology into a single story in which the chemistry of the environment plays a central role. They provide a fresh angle that may build new bridges in old debates.

How an interdisciplinary, environmental narrative of natural history promotes communication of controversial topics: Evolution, origin of life, and climate history

255th National Meeting (2018)

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