Origin Of Life

Over half a billion years earlier than dates usually given. From ScienceDaily: The researchers studied exceptionally well-preserved deposits which are approximately 3.5 billion years old in the ancient Dresser Formation in the Pilbara Craton of Western Australia. They interpreted the deposits were formed on land, not in the ocean, by identifying the presence of geyserite – a mineral deposit formed from near boiling-temperature, silica-rich, fluids that is only found in a terrestrial hot spring environment. Previously, the oldest known geyserite had been identified from rocks about 400 million years old. Within the Pilbara hotspring deposits, the researchers also discovered stromatolites – layered rock structures created by communities of ancient microbes. And there were other signs of early life in the Read More ›

From Suzan Mazur, author of Origin of Life Circus at Huffington Post, an interview with George Urtel: Georg Urtel: The hairpins are just being replicated. They are being replicated very inefficiently. Again, this has to do with the nature of the secondary structures. The hairpin structure is inhibiting because what the hairpin structure does is it forms a double helix with itself. When you have such a structure, the primer can’t bind. Suzan Mazur: What would you say is the significance of this experiment? Hasn’t it been known for many years that hairpins have a role in replication and recombination? Georg Urtel: Yes. The hairpin structure you find in all kinds of RNA enzymes, but the point here is that Read More ›

From PhilSci Archive: Abstract: Despite numerous and increasing attempts to define what life is, there is no consensus on necessary and sufficient conditions for life. Accordingly, some scholars have questioned the value of definitions of life and encouraged scientists and philosophers alike to discard the project. As an alternative to this pessimistic conclusion, we argue that critically rethinking the nature and uses of definitions can provide new insights into the epistemic roles of definitions of life for different research practices. This paper examines the possible contributions of definitions of life in scientific domains where such definitions are used most (e.g., Synthetic Biology, Origins of Life, Alife, and Astrobiology). Rather than as classificatory tools for demarcation of natural kinds, we highlight Read More ›

From Diana Kwon at The Scientist: While analyzing genetic material found in a wastewater treatment plant, scientists uncovered the genomes of four new species of related giant viruses. These newly discovered specimens, dubbed Klosneuviruses, challenge the notion that giant viruses evolved from a fourth domain of life, researchers wrote in a study published today (April 6) in Science. … Some scientists believe that rather than having a common ancestor, these giant viruses began as small viruses and gradually accumulated host genes over time. Analysis of the Klosneuvirus genome reveals evidence supporting the latter theory, according to the authors of the present study. More. These viruses have up to 1.57 million base pairs, with many genes encoded for components of translation Read More ›

One doesn’t use the word “miracle,” of course, but a friend pointed recently in passing to an older paper by Israeli philosopher of science Iris Fry, arguing that “near miracle” is a form of creationism: This paper calls attention to a philosophical presupposition, coined here “the continuity thesis” which underlies and unites the different, often conflicting, hypotheses in the origin of life field. This presupposition, a necessary condition for any scientific investigation of the origin of life problem, has two components. First, it contends that there is no unbridgeable gap between inorganic matter and life. Second, it regards the emergence of life as a highly probable process. Examining several current origin-of-life theories. I indicate the implicit or explicit role played Read More ›

From Linda Geddes at New Scientist: Metabolism may be older than life itself and start spontaneously However, the enzyme-free Krebs cycle that Ralser observed isn’t the complete biochemical cycle as it operates in modern cells. That may have come later, after enzymes evolved. Furthermore, the sulphate-driven cycle has so far only been shown to run in one direction (the oxidative one). In some species, the Krebs cycle can also run in reverse and help to incorporate CO2 into the building of new carbohydrates. Some think it may therefore have been involved in early carbon fixation, in which case you’d expect to see the cycle spontaneously turning in this direction too. Until researchers can demonstrate both these things, they cannot claim Read More ›

Also, doubts about horizontal gene transfer persist. First, from Suzan Mazur earlier at Huffington Post on deep evolution: I recently had a three-way phone conversation with Swedish deep evolution investigators Charles Kurland and Ajith Harish about their phylogenomic Tree of Life (ToL) based on protein structure, which shows that we are descended from a “complex” ancestor — MRUCA (most recent universal common ancestor) — not a simple bacteria. Kurland and Harish think a ToL paradigm shift may be in order. What’s more, Kurland and Harish figure that MRUCA was not the first ancestor, but represents complex survivors of a now-extinct biosphere. Now, just recently from Mazur, again at Huffington Post, a report on the pushback: There has been a vigorous and somewhat Read More ›

From Eric Berger at Ars Technica: Thanks to the ominous warning in Arthur C. Clarke’s novel, 2010: Odyssey Two, much of the science and technical community shares Culberson’s fascination with Europa. But for the general public, the icy moon remains largely an unknown. Eight billion dollars to peck at the ice on some moon around Jupiter? What is the sense of that? As he works on his peers in Congress, Culberson will eventually have to convince Joe the Plumber, Ken Bone, and the rest of America about the relevance of Europa, too. For this mission, he has a secret weapon. During the briefings at JPL, Culberson brought a friend with him, the famed Director James Cameron. The two men share Read More ›

But what are they? From Charles Cockell at Physics Today: Look at the menagerie of life—for example, as depicted by Jan Brueghel the Elder in the painting to the left. The casual viewer could easily conclude that life is limitless in its scope, that its forms and shapes are constrained only by the imagination. But however trite the observation may be, life must conform to the laws of physics. Science still does not know how many possible solutions there are to building a self-replicating system within those laws, however, or to what extent physics constrains the products of the evolutionary process. At the scale of organisms, physical laws certainly do limit the engineering solutions to life’s problems. For example, consider locomotion. Read More ›

From Nature: (paywall) Although it is not known when or where life on Earth began, some of the earliest habitable environments may have been submarine-hydrothermal vents. Here we describe putative fossilized microorganisms that are at least 3,770 million and possibly 4,280 million years old in ferruginous sedimentary rocks, interpreted as seafloor-hydrothermal vent-related precipitates, from the Nuvvuagittuq belt in Quebec, Canada. These structures occur as micrometre-scale haematite tubes and filaments with morphologies and mineral assemblages similar to those of filamentous microorganisms from modern hydrothermal vent precipitates and analogous microfossils in younger rocks. The Nuvvuagittuq rocks contain isotopically light carbon in carbonate and carbonaceous material, which occurs as graphitic inclusions in diagenetic carbonate rosettes, apatite blades intergrown among carbonate rosettes and magnetite–haematite Read More ›

From Sarah Kaplan at Washington Post on a recent find in northern Canada: The straw-shaped “microfossils,” narrower than the width of a human hair and invisible to the naked eye, are believed to come from ancient microbes, according to a new study in the journal Nature. Scientists debate the age of the specimens, but the authors’ youngest estimate — 3.77 billion years — would make these fossils the oldest ever found. Some apparent finds in recent years have not been found to be the residue of life, but in this case: But the scientists behind the new finding believe their analysis should hold up to scrutiny. In addition to structures that look like fossil microbes, the rocks contain a cocktail of Read More ›

Laura Geggel interviews virologists at LiveScience, who offer arguments against the idea, for example: “Take a cat, a plant and a rock, and leave them in a room for days,” said Amesh Adalja, an infectious disease physician and an affiliated scholar at the Johns Hopkins Center for Health Security in Baltimore. “Come back, and the cat and the plant will have changed, but the rock will essentially be the same,” he said. Like a rock, most viruses would be fine if they were left indefinitely in a room, Adalja said. In addition, he noted that living beings have self-generated and self-sustaining actions — meaning they can seek out sustenance and behave in self-preserving ways. In other words, “they’re taking actions Read More ›

From Journal of Molecular Evolution: ABSTRACT: A general framework for conventional models of the origin of life (OOL) is the specification of a ‘privileged function.’ A privileged function is an extant biological function that is excised from its biological context, elevated in importance over other functions, and transported back in time to a primitive chemical or geological environment. In RNA or Clay Worlds, the privileged function is replication. In Metabolism-First Worlds, the privileged function is metabolism. In Thermal Vent Worlds, the privileged function is energy harvesting from chemical gradients. In Membrane Worlds, the privileged function is compartmentalization. In evaluating these models, we consider the contents and properties of the Universal Gene Set of life, which is the set of orthologous Read More ›

From science writer Suzan Mazur, author of Paradigm Shifters, continuing her interview at Huffington Post with Swedish deep evolution investigators Charles Kurland and Ajith Harish regarding … their central position on deep evolution, which is that the most recent universal common ancestor (MRUCA) is complex not a simple bacteria and “is the root of eukaryote and akaryote lineages” containing “more than a thousand Superfamilies.” Kurland and Harish think MRUCA represents complex survivors from a now extinct biosphere. On horizontal gene transfer as routine: Charles Kurland: We have to remember there’s only a little background of horizontal gene transfer in bacterial populations. The simple reason is that bacteria eat DNA. So sequences are going in all the time. Most of them get Read More ›

From science writer Suzan Mazur, author of Paradigm Shifters, at Huffington Post: I recently had a three-way phone conversation with Swedish deep evolution investigators Charles Kurland and Ajith Harish about their phylogenomic Tree of Life (ToL) based on protein structure, which shows that we are descended from a “complex” ancestor — MRUCA (most recent universal common ancestor) — not a simple bacteria. Kurland and Harish think a ToL paradigm shift may be in order. What’s more, Kurland and Harish figure that MRUCA was not the first ancestor, but represents complex survivors of a now-extinct biosphere. The findings of Kurland and Harish challenge not only mainstream ToL perspectives, but also those of endosymbiosis hypothesis fans, as well as the “HGT industry” Read More ›