Book ReviewLarissa Tetsch
The Vital Question: Why is life the way it is?
Publisher: Profile Books Ltd
ASIN (Kindle Edition): B00MVAY7U6
€83 (Hardcover), €10 (Softcover), €7.55 (Kindle Edition)
Complex life has arisen only once in four billion years. Why have prokaryotes never managed to evolve the complex traits that all eukaryotes share? The Vital Question presents an intriguing answer: energy makes all the difference!
Having flipped through three pages of exalted praise, your reviewer wondered whether she could possibly like a science book that Bill Gates and the Wall Street Journal have recommended. Fortunately, she was soon rid of this worry. The Vital Question jumps right into what author Nick Lane calls a “black hole” at the heart of the history of life. Although we already know a lot about what life is, we have no idea why life is the way it is. Why did it arise so early and then stagnate in morphological complexity for several billion years? Why did complex, eukaryotic cells arise only once in four billion years and why haven’t we found any missing links between pro- and eukaryotes? And why does all life conserve energy in the form of proton gradients across membranes? These are only some of the questions biochemist and award-winning science writer Lane sets out to answer.
And he does so by thoroughly doing away with some of the hypotheses that have made it into the textbooks. It wasn’t a great oxygenation event that enabled the evolution of eukaryotes because, if so, those should have evolved independently from different bacterial groups. And neither did life evolve in a primordial soup, nor are archaezoa the longed-for missing link between pro- and eukaryotes, but instead they are “real” eukaryotes that have lost functional mitochondria.
While the reader still chews over this, energetics enters the picture and helps Lane to draw a mind-blowing picture of life’s origins in alkaline hydrothermal vents (which can be considered a somewhat milder version of the famous black smokers, see photo above). Here, a juxtaposition of alkaline fluids, rich in hydrogen, with acidic ocean water, enriched by carbon dioxide, produced a natural proton gradient across thin-walled catalytic micropores. This proton gradient may have, for the first time, driven the formation of organic compounds such as formaldehyde and methanol. Eventually – and twice – cells managed to escape these hydrothermal vents, giving rise to methanogenic archaea and acetogenic bacteria that evolved proton pumps, membranes and other traits independently from each other. This accounts for the fundamental differences between these two domains of life. If this scenario holds true, Lane postulates, life should evolve in more or less the same way everywhere in the universe on rocky, wet planets with abundant carbon dioxide.
Black smokers in the northeast Pacific Ocean. Photo: NOAA
However, to relieve the (energetic) constraints of the prokaryote cell, it needed a rare event: the endosymbiosis between two prokaryotic, and thus not phagocytic, cells. According to Lane, complex life could only arise after the acquisition of mitochondria that enabled host cells to dispose of 200,000 times more energy per gene than prokaryotes. The singular endosymbiosis event subsequently drove the enlargement of the host cell’s genome, of introns and the development of a nuclear membrane, the development of sexual reproduction by two sexes, an immortal germline and a mortal body, thus inventing death. Based on this theory, Lane concludes that complex life will probably be very rare throughout the universe. In its last chapters, the book illuminates the aftermath of having two genomes, a mitochondrial and a nuclear one, which must work perfectly together. This requirement of sophisticated coordination led to the development of species, to ageing and animals with different life spans according to their aerobic demands.
Pertaining to the basic assumption of endosymbiosis within a prokaryotic cell, for which examples indeed exist, it is unfortunate that the discovery of the Lokiarchaeota could not yet have been considered by Lane. The Lokiarchaeota were described as archaea on the basis of genome sequences roughly around the time that The Vital Question was published. They are hypothesised to actually be a kind of missing link between pro- and eukaryotes with a dynamic cytoskeleton and thus the ability for phagocytosis. Maybe this calls for a further epilogue in the book’s next edition?
Lane uses sophisticated thought experiments to develop his ideas, mostly supported by experimental facts that sometimes emerged only years after he had postulated a hypothesis for the first time. He has a talent for explaining complex processes and creates beautiful pictures to describe abstract molecular processes and energetic contexts. Although a trained biochemist might be tempted to skip the first basic chapters and to hop directly to Lane’s attempts at explanation, why miss out on this extraordinarily written and original state-of-the-art description of the fundamental processes of life?
What intrigued me most is that Lane, albeit presenting a highly complex subject, delivers the facts chattily with a very personal tone. He often stresses that he does not believe that he is correct in every detail but hopes to be so with the overall story, an almost humble self-assessment that contrasts with much of the available science literature. Often, it seems as if the reader is lurking over the author’s shoulder following his work and taking part in his train of thoughts. Many little summaries throughout the book make it a pleasure to follow Lane’s arguments which seem both plausible and creative. Finally, Lane’s enthusiasm is simply intoxicating. In summary, one of the best, if not the best science book, I have ever read!
Letzte Änderungen: 26.04.2017