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The origin and early evolution of life is generally studied under two different paradigms: bottom up and top down. Prebiotic chemistry and early Earth geochemistry allow researchers to explore possible origin of life scenarios. But for these “bottom–up” approaches, even successful experiments only amount to a proof of principle. On the other hand, “top–down” research on early evolutionary history is able to provide a historical account about ancient organisms, but is unable to investigate stages that occurred during and just after the origin of life. Here, we consider ancient electron transport chains (ETCs) as a potential bridge between early evolutionary history and a protocellular stage that preceded it. Current phylogenetic evidence suggests that ancestors of several extant ETC components were present at least as late as the last universal common ancestor of life. In addition, recent experiments have shown that some aspects of modern ETCs can be replicated by minerals, protocells, or organic cofactors in the absence of biological proteins. Here, we discuss the diversity of ETCs and other forms of chemiosmotic energy conservation, describe current work on the early evolution of membrane bioenergetics, and advocate for several lines of research to enhance this understanding by pairing top–down and bottom–up approaches.

Blog post with audio player, show notes, and transcript: https://www.preposterousuniverse.com/podcast/2020/01/06/78-d…fic-image/
Patreon: https://www.patreon.com/seanmcarroll.

Wilfrid Sellars described the task of philosophy as explaining how things, in the broadest sense of term, hang together, in the broadest sense of the term. (Substitute “exploring” for “explaining” and you’d have a good mission statement for the Mindscape podcast.) Few modern thinkers have pursued this goal more energetically, creatively, and entertainingly than Daniel Dennett. One of the most respected philosophers of our time, Dennett’s work has ranged over topics such as consciousness, artificial intelligence, metaphysics, free will, evolutionary biology, epistemology, and naturalism, always with an eye on our best scientific understanding of the phenomenon in question. His thinking in these areas is exceptionally lucid, and he has the rare ability to express his ideas in ways that non-specialists can find accessible and compelling. We talked about all of them, in a wide-ranging and wonderfully enjoyable conversation.

Continue reading “Mindscape 78 | Daniel Dennett on Minds, Patterns, and the Scientific Image” »

The ongoing AI revolution, set to reshape lifestyles and workplaces, has seen deep neural networks (DNNs) play a pivotal role, notably with the emergence of foundation models and generative AI. Yet, the conventional digital computing frameworks that host these models hinder their potential performance and energy efficiency. While AI-specific hardware has emerged, many designs separate memory and processing units, resulting in data shuffling and reduced efficiency.

IBM Research has pursued innovative ways to reimagine AI computation, leading to the concept of analog in-memory computing, or analog AI. This approach draws inspiration from neural networks in biological brains, where synapse strength governs neuron communication. Analog AI employs nanoscale resistive devices like Phase-change memory (PCM) to store synaptic weights as conductance values. PCM devices transition between amorphous and crystalline states, encoding a range of values and enabling local storage of weights with non-volatility.

A significant stride towards making analog AI a reality has been achieved by IBM Research in a recent Nature Electronics publication. They introduced a cutting-edge mixed-signal analog AI chip tailored for various DNN inference tasks. This chip, fabricated at IBM’s Albany NanoTech Complex, features 64 analog in-memory compute cores, each housing a 256-by-256 crossbar array of synaptic unit cells. Integrated compact, time-based analog-to-digital converters facilitate seamless transitions between analog and digital domains. Moreover, digital processing units within each core handle basic neuronal activation functions and scaling operations.

Daniel Dennett discusses the nature of consciousness, if consciousness is an illusion, artificial intelligence and virtual immortality, and how he covers all of this in his book, Just Deserts: Debating Free Will, co-authored with Gregg D. Caruso.

Just Deserts: Debating Free Will https://www.amazon.com/Just-Deserts-Debating-Free-Will/dp/15…atfound-20
Read an excerpt https://www.closertotruth.com/articles/book-excerpt-just-deserts.

Continue reading “Daniel Dennett on Consciousness, Virtual Immortality, and Panpsychism | Closer To Truth Chats” »

Researchers have developed an easy-to-build, low-cost 3D nanoprinting system that can create arbitrary 3D structures with extremely fine features. The new 3D nanoprinting technique is precise enough to print metamaterials as well as a variety of optical devices and components such as microlenses, micro-optical devices and metamaterials.

“Our system uses a two-step absorption process to realize 3D printing with accuracy reaching the nanometer level, which is suitable for commercial manufacturing,” said research team leader Cuifang Kuang from the Zhejiang Lab and Zhejiang University, both in China. “It can be used for a variety of applications such as printing micro or nanostructures for studying biological cells or fabricating the specialized optical waveguides used for virtual and augmented reality devices.”

Conventional high-resolution 3D nanoprinting approaches use pulsed femtosecond lasers that cost tens of thousands of dollars. In Optics Letters, Kuang and colleagues describe their new system based on an integrated fiber-coupled continuous-wave laser diode that is not only inexpensive but also easy to operate.

The discipline of systems chemistry deals with the analysis and synthesis of various autocatalytic systems and is therefore closely related to the study of the origin of life, since it investigates systems that can be considered as a transition between chemical and biological evolution: more complex than simple molecules, but simpler than living cells.

Tibor Gánti described the theory of self-replicating microspheres as early as 1978. These still lacked genetic material, but concealed within their membranes an autocatalytic metabolic network of small molecules, isolated (compartmentalized) within their membranes.

As the autocatalytic process takes place, the membrane-building material is also produced, leading to the division of the sphere. This system may appear to be a living cell, and although it lacks genetic material, this can only be verified experimentally. These microspheres can be considered as “infrabiological” chemical systems, since they do not reach the level of biological organization, but they exceed the complexity of normal chemical reactions.

Pythagoras first discovered that the vibrations of strings are drastically enhanced at certain frequencies. This discovery forms the basis of our tone system. Such natural vibrations ubiquitously exist in objects regardless of their size scales and are widely utilized to derive their species, constituents, and morphology. For example, molecular vibrations at a terahertz rate have become the most common fingerprints for the identification of chemicals and the structural analysis of large biomolecules.

Recently, natural vibrations of particles at the mesoscopic scale have received growing interest, since this category includes a wide range of functional particles, as well as most biological cells and viruses. However, natural vibrations of these mesoscopic particles have remained hidden from existing technologies.

These particles with sizes ranging from 100 nm to 100 μm are expected to vibrate faintly at megahertz to gigahertz rates. This frequency regime could not be resolved by current Raman and Brillouin spectroscopies, however, due to strong Rayleigh-wing scattering, while the performances of piezoelectric techniques that are widely exploited in macroscopic systems degrade significantly at frequencies beyond a few megahertz.

Turtles migrate thousands of miles out in the open ocean, charting epic courses in search of food, mates, and nesting grounds. Exactly how they find where they’re going has long puzzled scientists who suspected magnetic fields were involved, but were unsure of the exact mechanism through which turtles were sensing it.

We’ve since learned that turtles appear to recognize magnetic signatures of locations, such as the beach on which they hatched where females will later return to lay their own eggs. We know the magnetosphere is in constant flux, and turtle nesting sites have been found to shift in tandem, so how is it that they’re able to make sense of this invisible force?

Some answers to this question were revealed in a study that looked at the way snapping turtles can tell north from south, in a phenomenon known as spontaneous magnetic alignment. It was once thought to be a rare trait in the animal kingdom, but as Professor John Phillips from the Department of Biological Sciences at Virginia Tech told IFLScience, this is no longer the case.