Edited by Eörs Szathmáry
Volume 381, Pages 1-60 (21 September 2015)
Category: Science
Analysis of the vocabulary of 123 tabulated definitions of life reveals nine groups of defining terms (definientia) of which the groups (self-)reproduction and evolution (variation) appear as the minimal set for a concise and inclusive definition: Life is self-reproduction with variations.
https://doi.org/10.1080/073911011010524992
Pages 71-96 | Published online: 15 Apr 2008
https://doi.org/10.1080/01969727108545830
Proto-organisms probably were randomly aggregated nets of chemical reactions. The hypothesis that contemporary organisms are also randomly constructed molecular automata is examined by modeling the gene as a binary (on-off) device and studying the behavior of large, randomly constructed nets of these binary “genes.” The results suggest that, if each “gene” is directly affected by two or three other “genes,” then such random nets: behave with great order and stability; undergo behavior cycles whose length predicts cell replication time as a function of the number of genes per cell; possess different modes of behavior whose number per net predicts roughly the number of cell types in an organism as a function of its number of genes; and under the stimulus of noise are capable of differentiating directly from any mode of behavior to at most a few other modes of behavior. Cellular differentiation is modeled as a Markov chain among the modes of behavior of a genetic net. The possibility of a general theory of metabolic behavior is suggested. Analytic approaches to the behavior of switching nets are discussed in Appendix 1, and some implications of the results for the origin of self replicating macromolecular systems is discussed in Appendix 6.
The self-reproduction of supramolecular assemblies based on the synthesis and self-assembly of building blocks is a critical step towards the construction of chemical systems with autonomous, adaptive, and propagation properties. In this report, we demonstrate that giant vesicles can grow and produce daughter vesicles by synthesizing and incorporating phospholipids in situ from ad-hoc precursors. Our model involves acyl chain elongation via copper(I)-catalyzed azide-alkyne [3 + 2] cycloaddition reaction and the ensuing production of synthetic phospholipids to induce budding and division. In addition, the growth and budding of giant vesicles were compatible with the encapsulation and transfer of macromolecules as large as lambda phage DNA to the buds. This chemical system provides a useful model towards the implementation of cell-like compartments capable of propagation and transport of biological materials.
The potential for self-replication makes RNA an attractive candidate as a primordial catalysis in the origin of life. Catalysis may have occurred in some kind of compartment, possibly a fatty acid vesicle. However, RNA catalysis generally requires high levels of magnesium, which are incompatible with fatty acid vesicle integrity. Adamala and Szostak (p. [1098][1]) screened magnesium chelators and found that several—including citrate, isocitrate, and oxalate—could maintain the membrane stability of fatty acid vesicles in the presence of Mg2+. Citrate also allowed Mg2+-dependent RNA synthesis within protocell-like vesicles, while at the same time protecting RNA from Mg2+-catalyzed degradation. Efforts to recreate a prebiotically plausible protocell, in which RNA replication occurs within a fatty acid vesicle, have been stalled by the destabilizing effect of Mg2+ on fatty acid membranes. Here we report that the presence of citrate protects fatty acid membranes from the disruptive effects of high Mg2+ ion concentrations while allowing RNA copying to proceed, while also protecting single-stranded RNA from Mg2+-catalyzed degradation. This combination of properties has allowed us to demonstrate the chemical copying of RNA templates inside fatty acid vesicles, which in turn allows for an increase in copying efficiency by bathing the vesicles in a continuously refreshed solution of activated nucleotides. [1]: /lookup/doi/10.1126/science.1241888
Michael Marshall (Science)Hungarian biologist Tibor Gánti is an obscure figure. Now, more than a decade after his death, his ideas about how life began are finally coming to fruition.
Good to see Tibor Gánti finally getting some credit. This is a great little article with a nice overview of the Origin of Life problem (and references). The author Michael Marshall has a new book out on the topic.
ᔥ Peter Molnar in IndieWeb Chat ()
The ergodic hypothesis is a key analytical device of equilibrium statistical mechanics. It underlies the assumption that the time average and the expectation value of an observable are the same. Where it is valid, dynamical descriptions can often be replaced with much simpler probabilistic ones — time is essentially eliminated from the models. The conditions for validity are restrictive, even more so for non-equilibrium systems. Economics typically deals with systems far from equilibrium — specifically with models of growth. It may therefore come as a surprise to learn that the prevailing formulations of economic theory — expected utility theory and its descendants — make an indiscriminate assumption of ergodicity. This is largely because foundational concepts to do with risk and randomness originated in seventeenth-century economics, predating by some 200 years the concept of ergodicity, which arose in nineteenth-century physics. In this Perspective, I argue that by carefully addressing the question of ergodicity, many puzzles besetting the current economic formalism are resolved in a natural and empirically testable way.
Race is not a biological reality.
Racism thrives on our not knowing this.
Racist pseudoscience has become so commonplace that it can be hard to spot. But its toxic effects on society are plain to see--feeding nationalism, fueling hatred, endangering lives, and corroding our discourse on everything from sports to intelligence. Even well-intentioned people repeat stereotypes based on "science," because cutting-edge genetics are hard to grasp--and all too easy to distort. Paradoxically, these misconceptions are multiplying even as scientists make unprecedented discoveries in human genetics--findings that, when accurately understood, are powerful evidence against racism. We've never had clearer answers about who we are and where we come from, but this knowledge is sorely needed in our casual conversations about race.
How to Argue With a Racist emphatically dismantles outdated notions of race by illuminating what modern genetics actually can and can't tell us about human difference. We now know that the racial categories still dividing us do not align with observable genetic differences. In fact, our differences are so minute that, most of all, they serve as evidence of our shared humanity.
From the New York Times-bestselling author of How Not to Be Wrong, himself a world-class geometer, a far-ranging exploration of the power of geometry, which turns out to help us think better about practically everything
How should a democracy choose its representatives? How can you stop a pandemic from sweeping the world? How do computers learn to play chess, and why is learning chess so much easier for them than learning to read a sentence? Can ancient Greek proportions predict the stock market? (Sorry, no.) What should your kids learn in school if they really want to learn to think? All these are questions about geometry.
For real. If you're like most people, geometry is a sterile and dimly-remembered exercise you gladly left behind in the dust of 9th grade, along with your braces and active romantic interest in pop singers. If you recall any of it, it's plodding through a series of miniscule steps, only to prove some fact about triangles that was obvious to you in the first place. That's not geometry. OK, it is geometry, but only a tiny part, a border section that has as much to do with geometry in all its flush modern richness as conjugating a verb has to do with a great novel.
Shape reveals the geometry underneath some of the most important scientific, political, and philosophical problems we face. Geometry asks: where are things? Which things are near each other? How can you get from one thing to another thing? Those are important questions. The word geometry, from the Greek, has the rather grand meaning of measuring the world. If anything, that's an undersell. Geometry doesn't just measure the world - it explains it. Shape shows us how.
America’s coronavirus response failed because we didn’t understand the complexity of the problem.
Nice piece about some of the complexity surrounding the pandemic that we’re all missing out on. Good to see some complexity theory being considered in the public sphere.
This book is a further contribution to the series Cambridge Studies in Philosophy and Biology. It is an ambitious attempt to explain the relationship between intelligence and environmental complexity, and in so doing to link philosophy of mind to more general issues about the relations between organisms and environments, and to the general pattern of "externalist" explanations. This is a highly original philosophical project that will appeal to a broad swath of philosophers, especially those working in the philosophy of biology, philosophy of mind, and epistemology.
Dip below the ocean's surface and you are soon confronted by forms of life that could not seem more foreign to our own: sea sponges, soft corals, and serpulid worms, whose rooted bodies, intricate geometry, and flower-like appendages are more reminiscent of plant life or even architecture than anything recognizably animal. Yet these creatures are our cousins. As fellow members of the animal kingdom--the Metazoa--they can teach us much about the evolutionary origins of not only our bodies, but also our minds.
In his acclaimed 2016 book, Other Minds, the philosopher and scuba diver Peter Godfrey-Smith explored the mind of the octopus--the closest thing to an intelligent alien on Earth. In Metazoa, Godfrey-Smith expands his inquiry to animals at large, investigating the evolution of subjective experience with the assistance of far-flung species. As he delves into what it feels like to perceive and interact with the world as other life-forms do, Godfrey-Smith shows that the appearance of the animal body well over half a billion years ago was a profound innovation that set life upon a new path. In accessible, riveting prose, he charts the ways that subsequent evolutionary developments--eyes that track, for example, and bodies that move through and manipulate the environment--shaped the subjective lives of animals. Following the evolutionary paths of a glass sponge, soft coral, banded shrimp, octopus, and fish, then moving onto land and the world of insects, birds, and primates like ourselves, Metazoa gathers their stories together in a way that bridges the gap between mind and matter, addressing one of the most vexing philosophical problems: that of consciousness.
Combining vivid animal encounters with philosophical reflections and the latest news from biology, Metazoa reveals that even in our high-tech, AI-driven times, there is no understanding our minds without understanding nerves, muscles, and active bodies. The story that results is as rich and vibrant as life itself.
Some reviews of Luca's previous books"This book is like a magnificent suspension bridge, linking the science of the human brain to the practical craft of applying it in everyday life. I loved it." – Rory Sutherland, Ogilvy's Vice Chairman“A SUPERB book […] by one of the profound thinkers in our field [behavioral economics].” – Michal G. BartlettWhat's ergodicity, and why it matters?"The Most Important Property to Understand in Probability, in Life, in Anything." – Nassim Nicholas Taleb on ergodicity."I think the most under-rated idea is ergodicity." – David Perell, author.Is ergodicity the most important concept in decision-making and behavioral sciences? (Yes.)Is it relevant for you in your daily life? (Yes.)Is it possible to explain it so simply that a grandma or a high-schooler can understand it? (Yes.)Even if they know nothing about maths? (Yes.)That's because ergodicity is an important idea with so many practical applications. Sadly, most books describe it in a very technical way, making it inaccessible to most people.In this short book, 6-times author Luca Dellanna describes ergodicity as simply as possible. You will read stories about how not knowing about it destroyed his cousin’s career as a skier, or how misunderstanding it caused additional deaths during the pandemic. You will learn how to spot situations in which ergodicity matters and the three strategies to react appropriately.The book is approximately 166 pages long, of which 143 are pure content and the rest tables of content, etc.This page sells the eBook / Kindle version. Around mid-November, the paperback version will become available on Amazon and in selected stores (e.g., most Barnes & Noble).Who is this book for?This book is for readers interested in growing themselves, their career, or their business, and who want to learn about ergodicity and its practical applications without having to understand its mathematical foundation. No mathematical knowledge is required, only a high-school level understanding of English.Readers who want to master the theory and mathematical foundation of ergodicity are better off reading a more formal manuscript. This book is not a substitute for it, but a complement.You might also be interested in my second Roam book, on management (link).About the authorLuca Dellanna is the author of 7 books. He is a researcher in complexity science and emergent behaviors, and an operational excellence consultant. He spoke at Nudgestock and regularly teaches management workshops and risk management courses.His personal website is Luca-Dellanna.com and his Twitter is @DellAnnaLuca.What you will getBy purchasing this book, you will receive all of the following:PDF version.ePub version (compatible with Apple Books & other eBook readers).mobi version (Kindle)Moreover, you will get added to my mailing list, where I frequently publish essays that do not make it into books.The Roam versionThis book is also available as a Roam Research graph.Roam is a website that shows content in an interconnected way, a bit like Wikipedia. Reading the book this way will allow you to go back and forth content at your pace and following your interests."Ten minutes in, and I'm already questioning whether I'll want to read another non-fiction book *not* published in Roam format. How fascinating and so very valuable. Thank you Luca Dellanna" – Conor M. Ogle (link)Important: reading the Roam version requires a pre-existing Roam subscription, which is not included in this bundle.If you purchase the Roam version, you will receive the eBook in 3 formats (PDF, Kindle, and ePub) and the Roam version (as an editable .json export of the book) and a document suggesting how to import the Roam book and use it and the option to email me to request access to a live, read-only version of the book.Patron's supportThank you very much for your support, it helps me spending more time on my research.I will also add your name as a Patron in the acknowledgment section of the future editions of the book.Some more reviews of Luca's books“Luca’s book was so helpful to my work. Opened my eyes up to some more reasons why change is so hard.” – Chris Murman"A thoughtfully written book in very straightforward language." – A.L. PeeveyYou can find more reviews on the pages of my other books, such as this one.
This could be interesting as an overview to recommend
Going back to normal is not enough. A revamp is required.
The discovery of platypuses’ fluorescent fur has researchers wondering if the trait is more widespread among mammals than anyone has realized.