The Vital Question – Energy, Evolution, and the Origins of Complex Life

It’s a book. I read it. Clear explanations of a complex subject and a plausible scenario as to the origin of complex cells.

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I can understand why so many readers found this book difficult to comprehend. It's complicated. I’ll try and explain it as I understood it but feel free to correct me if you think I got it wrong. In a nutshell Nick Lane argues against the Darwinian theory that life began in a muddy pool somewhere and utilised the energy from the sun to form the first cell (commonly known as The Last Universal Common Ancestor or LUCA). Lane argues that life began in the abyss where hydrothermal vents utilised the energy supplied from the earth’s core heat which gave rise to LUCA. Many marine biologists and natural historians make the same claim (David Attenborough being the popular one) but none of them try to explain the science behind such a claim. At least Nick Lane tries to explain the science behind such an underwater event and for that reason alone he is worth persevering with.He argues that black smokers were unsuitable for the development of LUCA because they are too violent. Black smokers have chimneys that spew out vent fluid at 10 metres a second whereas white smokers don't have chimneys and vent their fluids more gently through a porous network of alkaline rock. Lane claims that the energy for the spark of life was due to proton gradients which allows the passage of electrical charges across a membrane of rock. There does not seem to be any quantum tunnelling involved, at least Lane never considers it. In Lane's theory proton gradients must be capable of rock-hopping. The problem as I see it is how hydrophobic and hydrophilic molecules (the Jekyll and Hyde molecules) formed the skin of LUCA in such a fluid percolating environment. The skin of LUCA is made up of three ingredients (the triacyglycerols) and LUCA needed a skin. Everything does. I just can't see that the development of a waterproof skin (commonly known as the cell membrane) would happen in such an environment. Where did the triacyglycerol ingredients come from? Dissolved minerals from the earth's mantle? Lane claims that the vent fluids of white smokers which are much lower in temperature than black smokers (the Goldilocks event horizon maybe) fed the developing LUCA.After a lot of dense scientific theorising Lane then claims that LUCA utilised two gases methane and CO2 to split itself into two to form the primordial archaea cell and bacteria cell. At this stage his theory gets a bit vague. These two cells, he surmises, are then released by the vents into the wider ocean. Unfortunately Lane then fails to develop this theory further, either that or I don't understand his thoughts which are pretty hard to follow. The problem (as I see it) is what happens to the two LUCA primordial cells (archaea and bacteria) after they have been released from the vents?Cells need to feed and once cut free from the vents they would lose their food supply. They would starve in the surrounding ocean. They are not eggs nor spores so can't hatch and develop into further prokaryotes and certainly not eukaryotes as eukaryotes would have required a much more sophisticated environment and millions of years to evolve through prokaryote symbiosis as described by biologist Lynne Margulis. How would that happen within the oceans?LUCA, under Lane's ‘release’ hypothesis would have been like an astronaut detached from his spacecraft, just one inch out of reach from home but guaranteed a certain death. Lane couldn't even convincingly claim that the two cells that developed from LUCA acquired their energy from eating each other as it would be pretty near impossible to rub shoulders with a fellow cell once released into the wider ocean, yet a common notion in early life theories is that LUCA spawned cannibal cells and progressed by devouring its offspring.The ocean is a vast space so how did they manage to contact each other to feed? His theory also doesn't explain the development of viruses either. He seems blind to the role they may have played in evolutionary development. Viruses are smaller than cells and have no metabolism themselves and exist as parasites but they need to be explained in early life theories, you can't just ignore them.Lane is clearly a down/up promoter, surmising that life progressed onto the earth's surface from within the sea (probably via the stromatolites). He mentions phagocytosis (whereby one cell engulfs another) but fails to recognise that some bacterial cells can engulf minerals rather than each other and deliberately set out to do so. The magnetosome prokaryote engulfs ferrous crystals which point it in the direction of the abyss to which it must swim downwards using its flagella. Magnetosome prokaryotes are one of the reasons I'm a proponent of the up/down hypothesis. I just don't buy the theory that the initial source of energy came from the earth's internal chemistry via white smokers in the abyss. Lane doesn't give credence to the idea that high pressure chemistry from black smokers played a part. For him it's all about energy from a slow vent flow.

If you are interested in the question of the origin of life on earth and you are not a biologist, then this is not the book for you. Try Simon Conway Morris, as an author he works harder for the non biologist.The book reads like an academic paper. The book is hyped with a multitude of endorsements and I disagreed with most of them. The origin of life as a theory is not complete it is a sketch and I fail to see how this research changes that. The book is a molecular biological interpretation of the second law of thermodynamics applied to cellular processes and nothing more. When I purchase a book I expect value. Nothing new here.

This book is an excellent review of the origins, based on molecular and cellular biology of the main groups of life (Bacteria, Archaea, and Eukaryotes...us, eventually!) It is written at a level where recent high school biology and perhaps undergrad university study wold be a help, and while I have all of that, and more, it would still be intelligible. Nick Lane is a good, pleasant style writer. While there are parts I don't quite understand because I am not as familiar with this discipline, it is very neat to see the pathways by which we evolved from 'water, rocks and carbon dioxide'. The wonder of abiogenesis is not out of reach.I heard about this book through Sean M. Carroll, the theoretical physicist of Mindscape podcast and blog, a source I trust, and I was pleased.

One of the best and influential book I have read in my lifespan

It is a very well written book, very entertaining, lots of knowledge. However, be aware that this book present only a single possibility (i.e., a theory) for the origin of life, which has also presented problems in recent years. Although very appealing, alkaline hydrothermal vents are not without their troubles.

Un livre essentiel pour suivre l'évolution de la connaissance, ici sur l'origine de la vie et les mécanismes qui en son le fondement,

Biochemistry is in the midst of a golden age of discovery and Nick Lane is at the forefront, winning numerous awards in his contributions to the life sciences. In this work, he has identified the vital unsolved questions in the field of biology and has provided plausible solutions to these mysteries including: the enigma of why life emerged only once on this planet, why no evolutionary intermediaries exist between simple and complex life, and the most vital question of all, how life began. During the earth’s four billion year history, it appears that life emerged only once, just 500 million years after the earth’s formation. Early life consisted of prokaryotes (cells without a nucleus) in the form of bacteria and archaea, a third domain of life discovered by Carl Woese in the 1960s. Over billions of years through extreme environmental and ecological changes, these organisms have filled every conceivable niche on our planet. Photosynthetic bacteria have bioengineered our planet on a colossal scale, creating the oxygen we breathe, changing the chemistry of the atmosphere and oceans, building up continents with sedimentary rock and minerals as their bodies fall to the ocean floor, in short, creating Gaia, our living planet. Yet, after all this time, they have shown little change in form or complexity. Then, seemingly without any intermediate steps, the eukaryotes (cells with a nucleus) sprang into existence giving rise to all plants, animals, and fungi found today. According to the cherished standard model of evolution, evolutionary changes occur incrementally. With this in mind it is hard to understand how complex eukaryotic cells appeared virtually overnight. In 1967, Biologist Lynn Margulis proposed a modification to the standard model of evolution. Her astute analysis of paleontological history revealed that evolution rarely occurs in a Darwinian or Malthusian way in which species battle for limited resources. Instead, she discovered that most evolutionary advances occur as a result of cooperation and symbiotic relationships. Margulis went further when she proposed the radical idea that cells cooperated so closely that they merged by getting inside one another. It is now widely accepted that mitochondria in animals and chloroplasts in plants are the result of endosymbiosis between bacteria and archaea. Author Nick Lane believes that early on in the history of life on earth complex eukaryotic cells arose on just one occasion through a singular endosymbiosis between an archaeon host cell and a bacterial invader creating the precursor of eukaryotic cells. Lane says that this endosymbiotic event might have occurred more than once but those experiments never survived. Over time, all of the complex features of modern eukaryotes including straight chromosomes, a membrane-bound nucleus, mitochondria, specialized organelles, a dynamic cytoskeleton, and total organism replication and reproduction arose by standard Darwinian evolution. Evolutionary theory tells us how life begets life, but it tells us nothing about how life began in the first place. This was the vital question Lane set out to solve. All cells, both eukaryotic and prokaryotic, have one essential commonality involving the method of energy production by burning food in the process of respiration. All living cells power themselves through a process of pumping protons across a membrane creating a reservoir of electrical imbalance. The back-flow of these protons is used by cells to produce physical work such as turning the rotors of nanomachines, just as water through a dam turns a turbine. This process provided Lane a clue in his attempt to find geochemical processes that would mimic biological energy production. If he could discover this mechanism in the natural world, it would go a long way in solving the mystery as to how life emerged from geochemical processes. In this vein, Lane formulated his own recipe for the emergence of biological chemistry from geochemistry—rock, water, and carbon dioxide. These simple ingredients are not only abundant in our atmosphere but are abundant throughout the known universe. But one cannot simply put these ingredients in a bowl and stir. To begin the chain of chemical reactions leading to life, it is necessary for hydrogen gas (H2) and carbon dioxide (CO2) to react with one another to produce one of the simplest organic molecules—methane (C4). This reaction does not occur under normal conditions. In fact, it is very difficult for hydrogen to react with carbon dioxide and this was one of the problems that confronted Lane. All cells derive their energy from reduction/oxidation (redox) reactions in which electrons are transferred from a donor to an accepter molecule. Typically, the accepter is oxygen but any two molecules can perform redox reactions. The molecule that receives electrons is said to be reduced and the molecule that gives up electrons is said to be oxidized. In respiration, or in a fire, where carbon is burned, oxygen is reduced to water, in which oxygen atoms pick up two electrons (as well as two protons that make up the hydrogen atom) producing a final product of water and carbon dioxide. In the case of hydrogen gas (H2), an alkaline, and carbon dioxide (CO2), an acid, it is hydrogen gas that wants to give up its electrons and become oxidized. Carbon dioxide, on the other hand, wants to accept electrons and be reduced. Each has a reduction potential, which is the amount of energy released when the reaction occurs. If a molecule (in this case hydrogen gas) wants to give up electrons, it has a negative value (-414 at a neutral PH) for a reduction potential, and alternatively, a molecule that wants to accept electrons, in this case carbon dioxide, has a positive value. The reduction potential is dependent on the acidity of a solution. High acidity increases the reduction potential of carbon dioxide making it more positive and easier to accept electrons whereas alkaline solution increases the reduction potential of hydrogen gas making it more negative and more likely to give up its electrons. One would think that by changing the acidity of a solution it would be easier for hydrogen gas and carbon dioxide to readily react with each other, but changing the acidity of a solution affects all of the molecules in the solution in the same way, so hydrogen gas (H2) will tend to pass on its electrons to H+ to form CO2 and H2. Nothing is gained and we’re right back where we started. Simply changing the acidity of a solution won’t make it any more likely carbon dioxide and hydrogen gas will react to produce methane. Lane was not deterred, believing that if there really is a continuum between geochemical and biological processes there should be a way to react CO2 with H2 naturally. He turned his thoughts to the ocean depths. Alkaline hydrothermal vents seemed to Lane to be good candidate for the continuum between geochemical and biochemical processes. Alkaline vents are not volcanic, but originate from the sea floor and are a product of a chemical reaction between water and rocks rich in olivine. Olivine is rich in ferrous iron and magnesium and when mixed with water the ferrous iron is oxidized to ferric oxide releasing heat and generating hydrogen gas dissolved in warm alkaline fluids containing magnesium hydroxides. According to Lane, alkaline hydrothermal vents have the perfect physical and chemical environment to kick-start life. Alkaline vents have a microporous structure like a sponge with thin electrically conductive walls separating interconnected pores. Warm currents passing through these micropores concentrate organic molecules such as amino acids, fatty acids, and nucleotides. The interactions between these molecules often precipitate fatty acids into vesicles, the precursors of cell walls, and occasionally they will polymerize amino acids and nucleotides into proteins and RNA. These porous vent structures mimic the biological structures in mitochondria that pump protons across a gradient. But before it is possible to concentrate organic molecules, it is necessary to create them and this was only one of the problems facing Lane: If these alkaline hydrothermal vents create life, then why aren’t they incubating life today? It occurred to Lane that conditions three and one half billion years ago in Hadean times are far different than conditions now. Under today’s conditions, there is not enough carbon to incubate life; however, estimates suggest that CO2 levels were anywhere from one hundred to one thousand times higher in Hadean times making the oceans more acidic. The combination of high carbon dioxide levels, mildly acidic oceans (PH 5-7), and warm alkaline fluids flowing through thin electrically conductive Iron sulfide vent walls would have made them ideally suited to react carbon dioxide with hydrogen gas to form methane (C4) as long as oxygen is not present. Under these conditions with temperatures between 25 and 125 degrees centigrade, the formation of all four of the macromolecules essential for life: amino acids, fatty acids, carbohydrates and nucleotides should form spontaneously from the reaction between hydrogen gas and carbon dioxide releasing energy in the process. Lane had found his geologic “mitochondria” in the form of alkaline vents on the ocean bottom. His hypothesis of a seamless transition between inorganic processes and organic processes was realized. Nick lane’s book The Vital Question is dense but accessible for the lay person who has patience. I think this is one of those landmark books that offer very plausible hypotheses for the vital questions concerning evolution, and the origins of life.