Is Earth the only planet that harbours life? According to the British biochemist Nick Lane, “Suitable conditions for the origin of life might be present, right now, on some 40 billion planets in the Milky Way alone”. By “life” he means prokaryotes, single-celled organisms devoid of a nucleus, which were the first living beings to appear on Earth. But what makes life on our planet remarkable is the abundance of complex eukaryotic life forms. The key is our beloved organelle, the mitochondrion, the powerhouse of the cell, or as the author calls it, “the thermodynamic epicentre of the cell”.
In his fifth book, Lane proposes a possible trajectory for realising complex life on the planet. He sets the stage by examining the evidential history of life on Earth and discusses past attempts to answer the question of its origin. He introduces the universal driver of life - chemiosmosis, in the simple form of proton gradients across membranes. Lane coherently transitions from the geochemistry of deep hydrothermal vent micropores four billion years ago to the biochemistry of primordial prokaryotes, laying a compelling narrative for the origin of chemiosmosis. However, the metabolic versatility of prokaryotes cannot generate the energy required for morphologically complex eukaryotes. Using Fermi estimates, he demonstrates the gigantic gap in energy between a typical prokaryote and an ancestral eukaryote, which he refers to as “the black hole at the heart of biology” at the start of the book. To tackle this, Lane walks us through the formation of mitochondria through endosymbiosis. In the process, he lays down hypothetical explanations for empirical observations like the hybrid nuclear membrane, introns, sex and death among other peculiarities of eukaryotic life. Towards the end of the book, he speculates on the role of mitochondrial and nuclear DNA coadaptation in the origin of speciation, imagines how greater aerobic capacity may link to extended lifespans, and remarks that “incorporating energy into evolution is long overdue”.
The book is a convincing narrative of biotic complexity from abiotic origins. The author lays a logical groundwork explaining the origin of metabolism and eukaryotic complexity but leaves aside the origin of replication. By standing on the shoulders of giants and filling in the gaps with his contributions and testable hypotheses, Lane shows that physical laws constrain chemical reactions, which transform into life under the right conditions. He uses jargon when necessary, with the occasional reminder of its meaning and a comprehensive glossary at the end of the book for forgetful individuals like me. This makes the book easy to read and surprisingly self-contained in its 368 pages. With 37 grayscale figures and corresponding descriptive labels, he creates a visual picture wherever possible. Lane avoids unnecessary digressions in his prose-style writing and masterfully weaves a captivating story accessible to a general audience.
I will recommend this book to anyone interested in (the origin of) life. Lane’s lucid writing makes cutting-edge science accessible to a vast audience, where he covers large ground without sacrificing accuracy. For the scientifically inclined, the book also contains a rich bibliography that is thematically arranged. The Vital Question makes several conceptual connections across scientific disciplines while attempting to uncover the origin of life. At the outset, this appears to be a formidable task, but Lane’s efforts make for an enlightening read and many of the bold ideas he proposes may hold the keys for future research.
