Have you ever wondered what "life" is? Not in the philosophical complexity of how hard it is to lead one, but what actually defines life in a scientific sense. Ever tried to comprehend the complexity of living, wondered on what makes "life", what concept or part it is that makes you say an organism is alive or dead? In the general sense, if you stop breathing, you are considered dead. Okay, you breathe, you walk, you talk. But what is it that makes you breathe autonomously in the first place? If you have ever thought in these lines and are amazed by life on earth, this is the perfect book to seek out answers for all the aforementioned nagging questions.The book starts with when the life is believed to have come into existence in the first place. The Precambrian explosion where the first life form arose 3.5 to 4 billion years back. These were bacteria and archaea which monopolized for a whopping ~2 billion years! Then, the earth's atmosphere only comprised of carbon, nitrogen, sulphur and iron. Then there was The Great Oxidation Event which led to that rare event - endosymbioses between a bacteria and an archaea - that the complex life, a eukaryote, as we see now arose, the endosymbiont turning out to be the mitochondria in our cells. Scientists have still not been able to reason out for this rare event, but have enormous evidence to prove that this was pivotal for complex life to flourish.The author, Nick Lane, also beautifully explains the "concept of life". Our life narrows down to the interplay between energy and entropy. What he calls the shopping list of life - a continuous flux of carbon and energy, the concoction of mineral catalysts in a compartmentalized system - present in a conducive atmosphere in hydrothermal vents is supposed to have formed life. Again, 'life' as an autonomous system is that always tends to increase the entropy of the system which increases the free energy available in the surroundings which is in turn consumed by organism to produce the energy currencies called ATP in mitochondria through respiration! Whoa!The book also talks about what constraints on the modern eukaryote led to the proliferation of complex life. The probability of a eukaryotic cell formed from the rarest of a rare event to turn out to modern humans or plants (yes, plants and we share a common ancestor :) ) is very low. But, the conditions on earth was too good to be ignored, giving rise to mutations and speciation by natural selection. The author also mathematically proves why it was feasible for a eukaryotic cell to evolve giving rise to a myriad kinds of species than having a monopoly of prokaryotes. Then comes the part where the author talks about how 'sex' arose, why are there only 2 sexes and the evolutionary benefit of having so. He gives a probable explanation for why scientists say the life anywhere else in the universe is hard to exist. The conditions are just very strict and events being as improbable as it might seem. Even if they do, he says it must be of the way as we have on earth as endosymbioses by the process of chemiosmosis is universal in cosmic terms.The author has laid out his theories of six years of research and argues why they might be true compared to all the theories we already know. He also openly accepts why his theories can be false or haven't yet been proved with enough evidence. The love for the subject and his work is clearly reflected in his writing.The book with all the scientific details can be tantalizing and hard to comprehend. I literally had to read almost every paragraph twice to understand the science behind his explanations. That can cause a bit of a detour, but I guess all that can be compensated when you realize how amazingly complex and magical life on earth is whilst reading those details!I highly recommend this book to all science fans, especially for those who are interested in the so called BIG questions of life. I felt reading the book, being awestruck at every page, repeatedly reading most parts to comprehend the details, was all worth my time. To have been evolved as an intelligent species as "homo sapiens" who have thrived since 200,000 thousand years with renaissance, industrial revolutions, agriculture, and all the scientific explorations over the past 500 years, we are a product of a slow, meticulous and intricate design of evolution, who are just the new guests to our planet which is 4.5 billion years old! We just got very lucky! :)P.S:1. This book was recommended as the Best Science Book of 2015 by Bill Gates. Read his review here - https://www.gatesnotes.com/Books/The-...2. Brief videos on the book by the awesome Joe Hanson in his Youtube channel "It's okay to be smart" can be found here https://www.youtube.com/watch?v=jdVc2... https://www.youtube.com/watch?v=Jf06M...

Wow this book was so interesting, it's main goal is to put forward the theory that the ability to harness energy by single cell organisms was the leap that was necessary for said organism to evolve into more complex organisms and therefore us, it explains the processes by which this could be possible attained 4 billion years ago, it argues that achieving this feat was nothing short of a miracle that it's very likely to not happen again. It also predicts that life in other planets would be similar to earth life at least in the molecular level , which it goes to explain we share with almost all organisms here on earth since complex life evolved from one single cell organism that achieved the ability to harness energy (ribosomes) , the ability to keep them in (double membrane ) and the motor to generate that energy (mitochondria) and therefore was able to escape the fate of single cell bacteria. I only give 4 stars to this book because this is not for the beginner , this is a very complex and technical albeit very informative book.

The Vital Question is a book about biochemistry. And author Nick Lane has made it as accessible as possible, but it still features a lot of terminology and concepts that may be less accessible to the lay reader. It certainly helps if you have a passing recollection of things like mitochondria, ribosomes, ATP/ADP, the Krebs cycle, the Calvin cycle, and the Acetyl-CoA pathway from your high school and/or college biochemistry classes. A basic understanding of the chemistry of acid-base reactions from your school days is also helpful. As a former biology major, I have all those tools and felt fairly comfortable with the text, but I can easily see someone without that background feeling lost a lot.Also know going in that we're going to spend a lot of time ruminating on what might have been going on, biochemically speaking, billions of years ago at a sub-cellular (and even sub-atomic) level in some primordial muck at the bottom of an ancient ocean. If that's not your bag, step away! None of this is criticism it's simply a warning that this is a book about a fairly specialized topic with a fairly specialized vocabulary and toolkit. With that in mind, I found it quite fascinating because it gets at some of the big questions behind, How did we get here? There are a lot of moments in a story like this where people of a certain inclination wouldn't hesitate to insert God anytime there's a question we don't know the answer to. Lane makes no bones that it's a common pitfall of this field of science. It's such a problem that a lot of biologists studying these kinds of questions are afraid to admit they don't know the answers because that gap is so vulnerable to people insisting that if we don't know, it must be God. But God per se isn't really the issue. A religious person can believe that God is the divine spark that set the universe in motion, without finding that God precludes scientific inquiry. You could even conclude that to study and try our best to understand God's incredible creation is a way of honoring God's work and perhaps even a kind of worship in itself. No, the problem is Christians of the biblical literalism flavor. Those are the ones who consider science the enemy because they're afraid the answers might not jibe with the Bible.The major point of this book isn't about the origin of life itself, but the origin of complex eukaryotic life. The simplest forms of life, prokaryotic bacteria, occurred fairly early in the earth's history, and were the only form of life for several billion years. But Lane does spend a chapter or two on the origins of the very first bacterial life, and makes the case reasonably well that the formation of the simplest living cells is probably not only not unique to earth, but common as dirt, and very likely all but inevitable on any wet, rocky planet that's warm enough to have liquid water, and has some carbon dioxide in its atmosphere... which is probably millions or even billions of planets in this galaxy alone.But the bad news is, Lane thinks the life that is almost certainly out there is almost certainly in the form of extremely simple single-celled bacteria-like organisms. As common as the basic building blocks of life are, the energy needed to run something even as complex as an amoeba is orders of magnitude higher that what the simplest living cells can produce, and requires an event much more rare... indeed, one that has happened only a very few times in the 4-billion year history of earth... an endosymbiosis between two of those simple cells that survives, thrives, and multiplies.Questions I had that I felt were never adequately answered:The central point that Lane makes quite hard early in this book is that the biologic innovation that led to the explosion of eukaryotic life the historic moment when one bacterium took up permanent residence inside another, and ultimately became the bioenergetic powerhouse that is our modern mitochondria was an incredibly unlikely event that has only happened once in the 4-billion-year history of the earth. Lane asserts we know this for a fact because all modern life is monophyletic; i.e., every eukaryotic life form today, from protozoa to elephants, is descended from a single eukaryotic ancestor. I immediately wondered, How do we actually know it only happened once? What if it happened hundreds of times but only one result worked well enough to survive and proliferate, and the others didn't last long enough to leave a trace in the fossil record? Lane does address this at one point, but brushes it off because only one was successful. But it seems to me this brush-off glosses over a flaw in the central premise if it happened lots of times then it's not an amazingly rare one-off event, is it? It only worked one time, but that's not the same as only ever happening one time.Then, every time Lane focused on how unique this endosymbiosis event was, I wondered, What about chloroplasts? It's widely accepted, and Lane agrees, that modern chloroplasts are the result of the precise same type of endosymbiosis event. So that makes not just one but two known times when it happened and worked, on a single planet, and an unknown number of times when it might have happened but the result failed to thrive. The case for endosymbiosis as a unique one-off event is looking a bit weaker. As Lane gets into the meat of the topic deep in the book, he admits that Okay, it's not unique, it's just rare. But in a billion years, even an incredibly rare event could still occur hundreds or thousands of times. And over billions of years on billions of planets... well you know what they say about a million monkeys clacking away at a million typewriters for a million years. Now make that billions and imagine what those monkeys could produce, particularly guided by a force as powerful as natural selection. In the epilogue, Lane discusses a never-before-seen microscopic cell discovered on a deep-sea hydrothermal vent which he speculates could be an example of it happening again, with humanity being lucky enough to see it in action this time. Unfortunately, the researchers who found it didn't get the chance to sequence the DNA of that cell, and after 15 years of searching, they've never been able to find another sample. This must be one of the failures.

This vital book filled in a huge gap in my understanding of the origins of life. I, like most folks, learned about the what and how of cells but never about where they came from. The soup-of-life, poof-out-of-air explanation was inferred. Understandably, we likely didn't focus on cellular origins in school because we don't have many definitive answers. There are some speculative elements in this book, but that's an inevitable by-product of trying to piece together 4 billion years of history.The most insightful section was about the origin of prokaryotic bacteria and archaea, the first forms of life. The author's argument that life arose from the hydrothermal vents at the bottom of the oceans was compelling and clear. After the first cells took form, the takeaway from the main takeaway is that the creation of complex cells can be attributed to the evolution of the mitochondria, which allowed cells to generate orders of magnitude higher amounts of energy to expand in size and develop distinctly-eukaryotic machinery like the nucleus. What I found most fascinating was the combination of chimeric, one-time events (e.g. endosymbiosis of bacteria and archaea) and the slow march of evolution (e.g. appearance of cell membranes) throughout the biological timeline. The prospect of life throughout the universe is plausible because there are evolutionary first principles, but also handicapped due to luck. We can deduce how many planets may have the required elements to kickstart complex life, but with a sample size of one (Earth), we don't know how probable is the spark. It was a bit of a struggle to get through the book with my limited recall of biology and chemistry. There's a base level of knowledge implied and some obscure terminology without explanations (e.g. soma). It's not the most approachable text, but this is a deep and worthy subject to think about critically.

I learned a lot from this book, and unlearned some old things about biology and biochemistry. Here's some notes I took about the book, to save on my computer:0s Nick Lane: The Vital Question1.Endosymbiosis was a one-off between an archaeon body and a bacterium that became mitochondrium. Golgi bodies may or may not have invaded later; other subbodies were likely produced by internal action, tho Lane doesnt specify.2.Archaea and bacteria didnt diversify at black smoker vents on seafloor ridges, but rather at warm, yet cooler, and gentler-venting alkali vents about 10-30 miles away, which, with multiple holes, provided a membrane for proton pumping along with alkali gradient vs. acidic seawater for reduction potential gradients for CO2 to reduce to formic, then to methanol, but stopping before methane, which isnt desired3.It made evolutionary sense for nucleus to uptake most mitochondrial genes4.Multicellular eukaryotes can either tolerate high levels of mitochondria vs nuclear gene defect rates and more adaptability, in exchange for short lives, (rats) or low tolerance and low birth rates, and low adaptability, in exchange for maintaining a high evolved fitness (birds, esp, which need high-performance mitochondria)5.High mitochondrial defect rates affect neurons and muscles above all, hence human neuromuscular disease, and per germ cells, hence their hitting men more. Muscles and nerves have the highest metabolic rate, and we cant replace out nerve cells, overall, in developed adults6.A modified version of the old free radical theory might be true while rejecting the idea that antioxidants can help (they can actually hurt, and not testing in body, rather than in lab, is how the original theory went wrong)7.Cellular free-radical links arent bad, theyre signals8.Mito-nuclear variants that affect ATP efficiency are linked to apoptosis, and seem to serve to signal it; apoptosis probably evolved early9.Mito defects are probably related to many early-pregnancy spontaneous abortions. (He says that 40 percent of all ends this way, even higher than Ayalas guess)10.Per reptiles and SRY defect in mammals, he thinks temperature of development is key for sex differentiation, to the point he thinks that if whats left of the Y chromosome finishes disintegration, mammals would find another temp-based way to distinguish sexes11.Re SETI, he says that the chemiosmotic nature of life on earth will probably be found elsewhere if we find life elsewhere12.Energy is less forgiving than genesThroughout, he specifies when he is being speculative. Within that, he notes what speculative items are testable. He then subnotes which of these he or his students are already testing, or others he knows of are already testing.