- ["Growth, efficiency, and yield of commercial broilers from 1957, 1978, and 2005"](https://academic.oup.com/ps/article/93/12/2970/2730506/Growth-efficiency-and-yield-of-commercial-broilers), Zuidhof et al 2014 ([media](http://www.vox.com/xpress/2014/10/2/6875031/chickens-breeding-farming-boilers-giant "Chickens have gotten ridiculously large since the 1950s"))
- ["Korea's Sooam Biotech Is the World's First Animal Cloning Factory"](http://www.businessweek.com/articles/2014-10-22/koreas-sooam-biotech-is-the-worlds-first-animal-cloning-factory)
This page is a changelog for Gwern.net: a monthly reverse chronological list of recent major writings/changes/additions.
Following my writing can be a little difficult because it is often so incremental. So every month, in addition to my regular /r/Gwern subreddit submissions, I write up reasonably-interesting changes and send it out to the mailing list in addition to a compilation of links & reviews (archives).
A subreddit for posting links of interest and also for announcing updates to gwern.net (which can be used as a RSS feed). Submissions are categorized similar to the monthly newsletter and typically will be collated there.
I ran a randomized experiment with a free program (Redshift) which reddens screens at night to avoid tampering with melatonin secretion & the sleep from 2012–2013, measuring sleep changes with my Zeo. With 533 days of data, the main result is that Redshift causes me to go to sleep half an hour earlier but otherwise does not improve sleep quality.
For nearly a century, twin and adoption studies have yielded substantial estimates of heritability for cognitive abilities, although it has proved difficult for genomewide-association studies to identify the genetic variants that account for this heritability (i.e., the missing-heritability problem). However, a new approach, genomewide complex-trait analysis (GCTA), forgoes the identification of individual variants to estimate the total heritability captured by common DNA markers on genotyping arrays. In the same sample of 3,154 pairs of 12-year-old twins, we directly compared twin-study heritability estimates for cognitive abilities (language, verbal, nonverbal, and general) with GCTA estimates captured by 1.7 million DNA markers. We found that DNA markers tagged by the array accounted for .66 of the estimated heritability, reaffirming that cognitive abilities are heritable. Larger sample sizes alone will be sufficient to identify many of the genetic variants that influence cognitive abilities.
Background: Cognitive ability tests are widely assumed to measure maximal intellectual performance and predictive associations between intelligence quotient (IQ) scores and later mental health problems. Very few epidemiologic studies have been done to demonstrate the relationship between familial inbreeding and modest cognitive impairments in children.
Objective: We aimed to estimate the effect of inbreeding on children’s cognitive behavior in comparison with non-inbred children.
Methodology: A cohort of 408 children (6 to 15 years of age) was selected from inbred and non-inbred families of five Muslim populations of Jammu region. The Wechsler Intelligence Scales for Children (WISC) was used to measure the verbal IQ (VIQ), performance IQ (PIQ) and full scale IQ (FSIQ). Family pedigrees were drawn to access the family history and children’s inbred status in terms of coefficient of inbreeding (F).
Results: We found significant decline in child cognitive abilities due to inbreeding and high frequency of mental retardation among offspring from inbred families. The mean differences (95% C.I.) were reported for the VIQ, being −22.00 (−24.82, −19.17), PIQ −26.92 (−29.96, −23.87) and FSIQ −24.47 (−27.35, −21.59) for inbred as compared to non-inbred children (p>0.001). The higher risk of being mentally retarded was found to be more obvious among inbred categories corresponding to the degree of inbreeding and the same accounts least for non-inbred children (p < 0.0001). We observed an increase in the difference in mean values for VIQ, PIQ and FSIQ with the increase of inbreeding coefficient and these were found to be statistically significant (p < 0.05). The regression analysis showed a fitness decline (depression) for VIQ (R2 = 0.436), PIQ (R2 = 0.468) and FSIQ (R2 = 0.464) with increasing inbreeding coefficients (p < 0.01).
Conclusions: Our comprehensive assessment provides the evidence for inbreeding depression on cognitive abilities among children.
I. J. Good’s thesis of the “intelligence explosion” states that a sufficiently advanced machine intelligence could build a smarter version of itself, which could in turn build an even smarter version, and that this process could continue to the point of vastly exceeding human intelligence. As Sandberg (2010) correctly notes, there have been several attempts to lay down return on investment formulas intended to represent sharp speedups in economic or technological growth, but very little attempt has been made to deal formally with Good’s intelligence explosion thesis as such.
I identify the key issue as returns on cognitive reinvestment—the ability to invest more computing power, faster computers, or improved cognitive algorithms to yield cognitive labor which produces larger brains, faster brains, or better mind designs. There are many phenomena in the world which have been argued to be evidentially relevant to this question, from the observed course of hominid evolution, to Moore’s Law, to the competence over time of machine chess-playing systems, and many more. I go into some depth on some debates which then arise on how to interpret such evidence. I propose that the next step in analyzing positions on the intelligence explosion would be to formalize return on investment curves, so that each stance can formally state which possible micro-foundations they hold to be falsified by historical observations. More generally I pose multiple open questions of “returns on cognitive reinvestment” or “intelligence explosion microeconomics.” Although such questions have received little attention thus far, they seem highly relevant to policy choices affecting outcomes for Earth-originating intelligent life.
This study investigates empirically the strengths and limitations of using experimental versus nonexperimental designs for evaluating employment and training programs. The assessment involves comparing results from an experimental-design study-the National Supported Work Demonstration-with the estimated impacts of Supported Work based on analyses using comparison groups constructed from the Current Population Surveys. The results indicate that nonexperimental designs cannot be relied on to estimate the effectiveness of employment programs. Impact estimates tend to be sensitive both to the comparison group construction methodology and to the analytic model used. There is currently no way a priori to ensure that the results of comparison group studies will be valid indicators of the program impacts. [Keywords: Public assistance programs, Analytical models, Analytical estimating, Employment, Control groups, Estimation methods, Random sampling, Human resources, Public works legislation, Statistical significance]
Ericsson and colleagues argue that deliberate practice explains expert performance.
We tested this view in the two most studied domains in expertise research.
Deliberate practice is not sufficient to explain expert performance.
Other factors must be considered to advance the science of expertise.
Twenty years ago, Ericsson, Krampe, and Tesch-Römer (1993) proposed that expert performance reflects a long period of deliberate practice rather than innate ability, or “talent”. Ericsson et al. found that elite musicians had accumulated thousands of hours more deliberate practice than less accomplished musicians, and concluded that their theoretical framework could provide “a sufficient account of the major facts about the nature and scarcity of exceptional performance” (p. 392). The deliberate practice view has since gained popularity as a theoretical account of expert performance, but here we show that deliberate practice is not sufficient to explain individual differences in performance in the two most widely studied domains in expertise research—chess and music. For researchers interested in advancing the science of expert performance, the task now is to develop and rigorously test theories that take into account as many potentially relevant explanatory constructs as possible. [Keywords: Expert performance, Expertise, Deliberate practice, Talent]
The immunity exhibited by plants and animals is often viewed as the evolutionary response to the problem of infectious agents. In this respect, the combination of the innate immune system and the acquired immune system has been characterized as the “optimal solution.” In this essay, I propose that there is no possibility of an optimal solution to the problem of parasitism. Regardless of the immunological mechanisms evolved, infectious agents establish a dynamic interaction with common strains of their host species, weighing virulence against transmissibility. In the endless host-parasite coevolution, the immune system can never gain an upper hand on the millions of parasitic microbes and viruses. Rather, evolution of the immune system is driven, most importantly, by the small advantages conferred as a result of host variation. By selecting for ever-more-devious parasites, the immune system is the cause of its own necessity.
The relationship between fertility and intelligence has been investigated in many demographic studies. There is evidence that, on a population level, intelligence is negatively correlated with fertility rate and positively correlated with survival rate of offspring. The combined net effect of these two conflicting forces on ultimate population intelligence is not well studied and is unclear. It is theorized that if an inverse correlation of IQ with fertility rate were stronger than the correlation of IQ with survival rate, assuming this continued over a significant number of generations, it could lead to a decrease in population IQ scores. The Flynn effect demonstrates an increase in phenotypic IQ scores over time, but confounding environmental factors during the same period of time preclude any conclusion concerning underlying change in genotypic IQ. Other correlates of IQ include income and educational attainment, which are also fertility factors that are inversely correlated with fertility rate, and are to some degree heritable. Although fertility measures offspring per woman, if one needs to predict population-level changes, the average age of motherhood also needs to be considered, with lower age of motherhood potentially having a greater effect than fertility rate.
The Tsiolkovsky rocket equation, classical rocket equation, or ideal rocket equation is a mathematical equation that describes the motion of vehicles that follow the basic principle of a rocket: a device that can apply acceleration to itself using thrust by expelling part of its mass with high velocity can thereby move due to the conservation of momentum.
[On the end to the post-WWII Vannevar Bushian exponential growth of academia and consequences thereof: growth can't go on forever, and it didn't.]
According to modern cosmology, the universe began with a big bang about 10 billion years ago, and it has been expanding ever since. If the density of mass in the universe is great enough, its gravitational force will cause that expansion to slow down and reverse, causing the universe to fall back in on itself. Then the universe will end in a cataclysmic event known as 'the Big Crunch'. I would like to present to you a vaguely analogous theory of the history of science. The upper curve on Figure 1 was first made by historian Derek da Solla Price, sometime in the 1950s. It is a semilog plot of the cumulative number of scientific journals founded worldwide as a function of time…the growth of the profession of science, the scientific enterprise, is bound to reach certain limits. I contend that these limits have now been reached.
…But after about 1970 and the Big Crunch, the gleaming gems produced at the end of the vast mining-and-sorting operation produced less often from American ore. Research professors and their universities, using ore imported from across the oceans, kept the machinery humming.
…Let me finish by summarizing what I've been trying to tell you. We stand at an historic juncture in the history of science. The long era of exponential expansion ended decades ago, but we have not yet reconciled ourselves to that fact. The present social structure of science, by which I mean institutions, education, funding, publications and so on all evolved during the period of exponential expansion, before The Big Crunch. They are not suited to the unknown future we face. Today's scientific leaders, in the universities, government, industry and the scientific societies are mostly people who came of age during the golden era, 1950–1970. I am myself part of that generation. We think those were normal times and expect them to return. But we are wrong. Nothing like it will ever happen again. It is by no means certain that science will even survive, much less flourish, in the difficult times we face. Before it can survive, those of us who have gained so much from the era of scientific elites and scientific illiterates must learn to face reality, and admit that those days are gone forever.
Bitcoin has enjoyed wider adoption than any previous cryptocurrency; yet its success has also attracted the attention of fraudsters who have taken advantage of operational insecurity and transaction irreversibility. We study the risk investors face from the closure of Bitcoin exchanges, which convert between Bitcoins and hard currency. We examine the track record of 80 Bitcoin exchanges established between 2010 and 2015. We find that nearly half (38) have since closed, with customer account balances sometimes wiped out. Fraudsters are sometimes to blame, but not always. 25 exchanges suffered security breaches, 15 of which subsequently closed. We present logistic regressions using using longitudinal data on Bitcoin exchanges aggregated quarterly. We find that experiencing a breach is correlated with a 13-times greater odds that an exchange will close in that same quarter. We find that higher-volume exchanges are less likely to close (each doubling in trade volume corresponds to a 12 percent decrease in the odds of closure). We also find that exchanges who derive most of their business from trading less popular (fiat) currencies, which are offered by at most one competitor, are less likely to close.
A breaker boy was a coal-mining worker in the United States and United Kingdom whose job was to separate impurities from coal by hand in a coal breaker. Although breaker boys were primarily children, elderly coal miners who could no longer work in the mines because of age, disease, or accident were also sometimes employed as breaker boys. The use of breaker boys began in the mid-1860s. Although public disapproval of the employment of children as breaker boys existed by the mid-1880s, the practice did not end until the 1920s.
A crossing sweeper was a person working as a street sweeper who would sweep a path ahead of people crossing dirty urban streets in exchange for a gratuity. This practice was an informal occupation among the urban poor, primarily during the 19th century. It was the focus of fairly intense study and commentary, and attitudes toward the presence of crossing sweepers on city streets varied greatly among urban residents, ranging from appreciation for their work to feelings that they were a public nuisance. Crossing sweepers also found their way into 19th-century fiction and artwork, including a novel by Charles Dickens and a popular painting by William Powell Frith.
A dog whipper was a church official charged with removing unruly dogs from church grounds during services. They were most prominent in areas of England and continental Europe between the 16th and 19th centuries.
Wrongful life is the name given to a legal action in which someone is sued by a severely disabled child for failing to prevent the child's birth. Typically, a child and the child's parents will sue a doctor or a hospital for failing to provide information about the disability during the pregnancy, or a genetic disposition before the pregnancy. Had the mother been aware of this information, it is argued, she would have had an abortion, or chosen not to conceive at all.
Kill la Kill is a 2013 Japanese anime television series produced by Trigger. The series follows vagrant schoolgirl Ryuko Matoi on her search for her father's killer, which brings her into violent conflict with Satsuki Kiryuin, the iron-willed student council president of Honnouji Academy, and her mother's fashion empire. In the show, characters obtain superpowers from specialized clothing due to the presence of a material known as Life Fibers.
Subscription page for the monthly gwern.net newsletter. There are monthly updates, which will include summaries of projects I’ve worked on that month (the same as the changelog), collations of links or discussions from my subreddit, and book/movie reviews. You can also browse the archives since December 2013.
Newsletter tag: archive of all issues back to 2013 for the gwern.net newsletter (monthly updates, which will include summaries of projects I’ve worked on that month (the same as the changelog), collations of links or discussions from my subreddit, and book/movie reviews.)
The theoretical framework presented in this article explains expert performance as the end result of individuals' prolonged efforts to improve performance while negotiating motivational and external constraints. In most domains of expertise, individuals begin in their childhood a regimen of effortful activities (deliberate practice) designed to optimize improvement. Individual differences, even among elite performers, are closely related to assessed amounts of deliberate practice. Many characteristics once believed to reflect innate talent are actually the result of intense practice extended for a minimum of 10 yrs. Analysis of expert performance provides unique evidence on the potential and limits of extreme environmental adaptation and learning.