A review of the synaptic plasticity and memory hypothesis arguing that it is insufficient to explain memory, and proposing a broader cellular processes and memory hypothesis that includes molecular and intracellular mechanisms. Longer summary

The post reviews the synaptic plasticity and memory (SPM) hypothesis, which claims that learning and memory are stored in changes to synaptic weights between neurons. Through several compelling examples, from cannibalism rituals to heart transplant stories and single-cell learning, the author argues that while the SPM hypothesis has been productive, it is incomplete and partially wrong. The post presents evidence that memory can be stored through non-synaptic mechanisms, and proposes an alternative called the cellular processes and memory (CPM) hypothesis, which suggests memory storage involves multiple molecular and intracellular processes beyond just synaptic weights. Shorter summary

Scott reviews Bryan Caplan's book arguing that modern parents can relax their intensive parenting, while wrestling with whether this advice still applies in the age of smartphones and social media. Longer summary

Scott reviews Bryan Caplan's book 'Selfish Reasons To Have More Kids', exploring its main arguments about how parents today spend much more time on childcare than previous generations despite evidence that parenting style doesn't greatly affect outcomes. The post explores historical childcare data, the cultural shift away from letting kids play unsupervised, and modern challenges like screen time. Scott, dealing with his own twins, finds the book's advice about relaxing parenting standards compelling but struggles with modern concerns about phones and technology that weren't relevant when the book was written in 2011. Shorter summary

Scott Alexander examines the surprisingly broad effects of GLP-1 drugs like Ozempic, exploring their mechanisms and speculating on why they seem to impact so many different conditions. Longer summary

Scott Alexander explores the wide-ranging effects of GLP-1 receptor agonist medications like Ozempic, which are approved for diabetes and obesity but show promise for many other conditions. He delves into the mechanisms behind their effects on diabetes, weight loss, and addiction, speculating on why these drugs seem to have such broad impacts. The post discusses how GLP-1 drugs work in the brain to reduce hunger and dampen reward systems, potentially explaining their effects on addiction. Scott also touches on their anti-inflammatory properties and potential benefits for neurodegenerative diseases, while cautioning that some reported effects may not replicate. Shorter summary

Scott Alexander responds to comments on his COVID-19 origins debate post, addressing criticisms and maintaining his support for the zoonosis theory. Longer summary

Scott Alexander provides a detailed response to comments and criticisms of his previous post on the COVID-19 origins debate. He addresses arguments against zoonosis, clarifies misunderstandings, and discusses the methodologies used by various parties in the debate. He maintains his position favoring zoonosis over lab leak, while acknowledging the complexity of the issue and the ongoing nature of the debate. Shorter summary

Scott Alexander investigates the claim that children learn languages faster than adults, finding it partially true but more nuanced than commonly believed. Longer summary

Scott Alexander examines the claim that children learn languages faster than adults, finding it to be partially true but more complex than commonly believed. He explores various aspects of language acquisition, including critical periods for first language learning, age effects on second language learning, and differences in learning rates between children and adults. The post concludes that while children seem to pick up second languages faster than adults, this advantage is not as clear-cut as often thought, and factors like exposure, motivation, and declining learning rates with age play significant roles. Shorter summary

Scott Alexander summarizes and responds to comments on his post about semaglutide, covering corrections, additional information, and user experiences with the weight loss drug. Longer summary

Scott Alexander summarizes and responds to comments on his previous post about semaglutide, a weight loss drug. The highlights include corrections to his original analysis, additional information on obtaining semaglutide cheaply, discussion of other weight loss drugs and treatments, challenges to Scott's predictions, debate over whether weight loss is maintained after stopping the drug, personal anecdotes from users, and mentions of some tangential debates in the comments. Shorter summary

Scott Alexander examines obscure pregnancy interventions that may improve child outcomes, rating them by evidence quality and potential impact. Longer summary

Scott Alexander reviews various obscure pregnancy interventions that could potentially improve child outcomes, particularly IQ. He rates them in tiers based on evidence strength and potential impact, with Tier 1 being most strongly supported. Key interventions discussed include embryo selection, choline supplementation, avoiding stress and certain substances, and optimizing birth timing. He emphasizes these are extreme measures not meant to induce guilt, and that standard pregnancy advice is still most important. Shorter summary

Scott Alexander discusses the birth of the first polygenically-screened baby and explores the current and potential future applications of this technology in IVF. Longer summary

Scott Alexander discusses the birth of the first polygenically-screened baby, explaining the process of in vitro fertilization (IVF) and how polygenic screening works. He describes how this technology can be used to reduce the risk of genetic diseases and potentially select for other traits. The post covers the current capabilities of polygenic screening, its potential future applications, and some ethical considerations. Scott also mentions the first polygenically screened baby, named Aurea, born to a family with a history of breast cancer. Shorter summary

Scott Alexander explores Hallucinogen Persisting Perception Disorder (HPPD) and other conditions where drugs cause permanent effects, discussing potential mechanisms and their implications. Longer summary

Scott Alexander discusses Hallucinogen Persisting Perception Disorder (HPPD), a condition where some people experience permanent hallucinatory effects after using psychedelic drugs, particularly LSD. He explores the prevalence, potential mechanisms, and implications of this disorder. The post compares HPPD to other conditions with persistent effects like tardive dyskinesia, and examines various theories about how drugs could cause permanent changes in the brain. Scott considers two main hypotheses: the killing-off of specific neurons, and the idea of the brain as a chaotic system settling into new attractor states. He expresses a preference for the neuron death theory as it seems more understandable and less scary, but acknowledges the complexity and uncertainty surrounding these issues. Shorter summary

Scott Alexander attempts to understand and explain Karl Friston's complex 'free energy' principle in neuroscience, exploring its various interpretations and potential implications. Longer summary

Scott Alexander explores Karl Friston's work on 'free energy', a complex concept in neuroscience that has been described as a unified brain theory. The post delves into various interpretations of free energy, from its mathematical origins in Bayesian equations to its application in explaining perception, cognition, homeostasis, and action. Scott struggles to fully grasp the concept, acknowledging its complexity and the widespread difficulty in understanding Friston's work. He presents different perspectives on free energy, including its role in uncertainty reduction, its connection to predictive processing, and its potential to explain biological systems and the origin of life. The post concludes with a tentative synthesis of these ideas and raises questions about the implications of the free energy principle for machine ethics. Shorter summary

A collection of interesting links spanning architecture, science, politics and economics, with commentary on studies about lithium, lead exposure, minimum wage, and free speech. Longer summary

This is a links post where Scott Alexander shares various interesting articles and studies from around the internet. It covers a wide range of topics including architecture, science, politics, economics, and social issues. Notable items include a study showing lithium in drinking water may not have significant effects, research about the lead-crime hypothesis, discussions about minimum wage studies in Seattle, and various pieces about free speech and campus politics. Shorter summary

A collection of interesting links covering various topics from scientific studies, social issues, and current events, including problems with brain imaging studies, AI safety developments, and surprising research findings. Longer summary

This is one of Scott's regular link posts where he shares and briefly comments on interesting articles and studies he's found. The post covers diverse topics including medical research critique (particularly brain imaging and psychiatric studies), current events (like the Chinese government's actions against Buddhist monks), and technological developments in AI safety. Scott adds his characteristic analytical commentary to many of the links, pointing out surprising implications or potential flaws in the studies. The format is casual but informative, with Scott often expressing personal opinions or humorous observations about the material he's sharing. Shorter summary