cover image Oxygen: A Four Billion Year History

Oxygen: A Four Billion Year History

Donald E. Canfield. Princeton Univ., $29.95 (256p) ISBN 978-0-691-14502-0

As ecologist Canfield explains it, “Oxygen is a signature feature of Earth; the high levels in our atmosphere define the outlines of our existence, as they also generally define the nature of animal life on Earth.” But this has not always been the case. Canfield’s work explores the atmospheric composition of the planet in past and seeks to understand the processes that led to the changes that have occurred. He blends heavy doses of biology with geology and geochemistry to present current hypotheses about how the Earth’s “great oxidation” took place “between 2.3 and 2.4 billion years ago,” resulting from the rise of cyanobacteria coupled with a reduction in the Earth’s tectonic activity as the planet’s core cooled. Much of the work Canfield discusses was conducted by him and his direct collaborators and mentors. Beyond the actual science—which is often presented in a way that is complex enough to deter a general readership—his excellent descriptions of the scientific process show how competing hypotheses, and the scientists who present them, vie for supremacy. Canfield also offers a philosophical perspective: scientific understanding provides true insight into the structure of the natural world and reveals that “science will converge on these ideas, if not now by one scientist, then later by another.” (Jan.)