Ascientific question can be viewed as a puzzle, and a book about a scientific discovery can be written as a puzzle revealed. Martin Brasier's new book, Secret Chambers: The Inside Story of Cells and Complex Life, is presented as a detective's quest for answers to one of the great scientific mysteries: How did a complex compartmentalized (i.e., eukaryotic) cell originate and evolve into the many diverse life forms that we see today? In this search, the book uniquely takes both the reader and the author to evolutionary events that occurred billions of years ago.
Time travel is a usual pastime for Brasier, who is a professor of paleobiology at the University of Oxford and a global hunter of fossils that span the Archaean and Proterozoic eons. Entertaining autobiographical notes of his field trips add to the adventurous mood of the book's narrative.
As with any good mystery novel, Secret Chambers entices its readers with multiple parallel and, at first, seemingly unrelated stories: surveys of coral reefs in the world's oceans, a close examination of algal and foramineran cellular structures, and a study of mass extinction patterns throughout Earth's geological history. After a brief historical foray into England during the Age of Enlightenment and later, during the Victorian era, to meet Robert Hooke, Charles Darwin, Robert Brown, and Charles Lyell, we are teleported aboard the HMS Fawn in the Sargasso Sea, where Brasier served as the ship's naturalist in 1970s. Here, we are introduced to a complex cell's internal structure, and we are faced with questions pertaining to its origin: Which events led to the creation of cellular compartments? When and where did it happen? Why did it happen only a few times, and why only in the distant past? What fossil evidence supports our conjectures? Answers to these questions eventually converge from the multiple threads of the narrative, although, as with many scientific investigations that are still in progress, we are left with only a partial and speculative understanding.
I applaud Brasier's attempts to explain complex topics with poetic and vivid metaphors, but I take note of some oversimplifications and mistakes that crept into these analogies. For example, when the author compares a mitochondrion to a ship's engine, he describes the burning of adenosine triphosphate (ATP)—the cell's “fuel”—as taking place within the organelle to release energy. In fact, the opposite happens there: ATP is made to trap the energy that is created from the oxidation of carbohydrates,fats, and amino acids. In the analogy of the Tree of Life using a mangrove, living entities are presented in a progression from bacteria (i.e., the roots of the mangrove) to animals and plants (i.e., the branches of the mangrove). Although the analogy helps to illustrate the multiple bacterial contributions to the eukaryotic cell, the Mangrove of Life has a greater resemblance to the genealogical view of eukaryotic ancestry than to contemporary visions of the Web of Life (Ragan 2009).
Another misstep of the book is that although the origin of chloroplasts is thoroughly covered, the origins of the mitochondrion and the nucleus are mentioned only in passing. It is the origin of the mitochondrion, however, that is at the crux of the ongoing eukaryogenesis debate, because many eukaryotes do not have chloroplasts, but they virtually all have mitochondria. The book's focus on chloroplasts leads to Brasier's failure to present the differing sides of the argument, a point of contention fueled in part by genomic and phylogenetic data and involving two rival models—the phagotrophy model, in which a protoeukaryote engulfs a bacterium, and the syntrophy model, in which an archaeon and bacterium merge to form a new type of cell (O'Malley 2010). Without mentioning this ongoing rivalry between two conceptually different eukaryogenesis propositions, Brasier inadvertently hides part of the history of the eukaryotic cell from the reader.
All flaws aside, Secret Chambers achieves what the author intended. It is a lively, partly historical, and mostly personalized account of the quest to understand the evolutionary history of the eukaryotic cell. Designed for the lay reader, the book also can be inspirational to high school and undergraduate students. Brasier weaves side discussions throughout his book about the usefulness of knowing how various approaches can be employed by scientists in order to find solutions to the puzzles of scientific queries. It is most likely Brasier's hope that students of various majors will read Secret Chambers and learn how the combined fields of paleontology, biology, evolution, and mathematical modeling contribute to the investigation of the origin of the eukaryotic cell.
J. Peter Gogarten (University of Connecticut) is thanked for his comments and suggestions.