In one year China is making 107 towers taller than 200m. The US needed decades to build 189 ones.

Asia Dreams in Skyscrapers. By Jason M Barr
https://www.nytimes.com/2017/10/11/opinion/china-asia-skyscrapers.html
The New York Times, Oct 11 2017

The skyscraper was born in the United States, but in recent years, it has grown and flourished in Asia. Countries there recognize that to be seen as a player on the global stage, it helps to have tall buildings.

Over a century ago, New York and Chicago demonstrated that the skyscraper is, fundamentally, a solution to an economic problem: how to allow for hundreds, if not thousands, of people and businesses to be at the same place at the same time. Urban clustering, especially in a high-tech world, is more important than ever. By promoting density, skyscrapers confer a competitive advantage and allow a city to become a beacon of commerce.

In April, President Xi Jinping of China announced plans for a new city, Xiongan, not far from Beijing. A kind of Chinese field of dreams, Xiongan is to be built on what is now hundreds of square miles of farmland and towns, house millions of people and be a center for technology jobs. Like the cities it’s being modeled after — Shenzhen, near Hong Kong, and Shanghai, particularly its Pudong neighborhood — it may someday claim the world’s tallest skyscrapers. The Ping An Finance tower in Shenzhen, completed this year, at 115 stories, is the fourth-tallest building in the world, while the Shanghai Tower, completed in 2015, at 128 stories, is the second-tallest skyscraper on the planet.

Since the 1990s, the world’s tallest buildings have been built in the East. The current prize holder — the Burj Khalifa in Dubai, United Arab Emirates (828 meters, or about 2,717 feet, 2010) — will be soon be surpassed by the Jeddah Tower in Saudi Arabia (1,000 meters, or about 3,281 feet, 2020). Nine of the 10 world’s tallest buildings are in Asia. In addition, the continent now has more 150-meter (about 492 feet) or taller buildings than the rest of the continents combined.

An awe-inspiring skyline is a city’s announcement that it is open for business and confident in its future growth. Supertall structures stand as “place makers” in the planning process, since they create neighborhood landmarks to draw companies, residents, tourists and foreign direct investment. China is now a nation full of capitalists. Arab workers are no longer just oil drillers, but global traders and financiers.

But just as important, cities that have record-breaking buildings are not just constructing super-tall monoliths. There is a strong correlation between the number of tall buildings of all sizes and the likelihood a city will have a supertall building; heights and frequencies are strongly related. The Burj Khalifa and Shanghai Tower, for example, are the most visible signs that a city embraces skyscrapers more broadly to enhance economic growth and the quality of life of residents and companies.

Consider where these nations stand. Over the last decade, the average annual gross domestic product growth rates in India, China, Indonesia and Malaysia were, in most years, more than three times that of the United States. As part of this development, nations expand their financial and banking sectors; research shows that skyscrapers are needed for this to happen.

Furthermore, China is witnessing what is arguably the greatest internal migration in human history. In 1979, only about 19 percent of its residents lived in urban areas; today that figure is about 57 percent, and this movement shows no sign of slowing. To put this in perspective, the number of Chinese residents who have moved to cities since 1979 (600 million) is greater than the total current population of North America (580 million). By comparison, in 1900, urbanization in the United States was at 40 percent; by 1970, it was up to 74 percent, and has since inched up to 82 percent.

Given this rapid growth, governments generally have two options: They can encourage tall buildings to satisfy the urban demand, or they can restrict building heights, which then increases sprawl, congestion and the distances between people. As a result, Asian governments establish land-use rules that increase density, as well as sponsor international architecture competitions, provide subsidies or simply lend support. Across China, we see a strong correlation between the heights of cities’ skyscrapers and the size of their populations and local economies.

Interestingly, the Chinese government has also indirectly created political incentives for their construction. Because of one-party rule, career promotion within the Communist Party is based on the ability to “get things done” — and building skyscrapers can serve that purpose. Recent research suggests that younger local officials build more skyscrapers and invest in more infrastructure to enhance their standing within the government.

In the United States, high-rise construction remains controversial. Though things are starting to change, at its core, the country remains dedicated to promoting single-family homes in the suburbs and sprawling car-dependent office parks. Many municipalities put up hurdles for tall building construction, allowing them only in densest parts of the central city. As a result, we see a flowering of new supertall buildings there, but they are frequently derided as “safe deposit boxes with views.” Because of the negative perceptions, it has become difficult to have conversations about how they can make cities more resilient and less dependent on fossil fuels.

What is the future of the skyscraper? As long as Asian countries pursue lifestyles similar to that of the West, skyscrapers will continue to be built, as they not only help foster economic growth, but also establish a city’s skyline, which then becomes part of a city’s identity and character.

As technological improvements make building skyscrapers easier and faster, the race for the world’s tallest building will continue as well. Since 1890, their heights have grown, on average, about 17 feet per year. Statistically speaking, this suggests that a mile-high building will be built in the middle of the 22nd century. But don’t tell that to Tokyo, which wants to get there first by 2045.

Jason M. Barr, a professor of economics at Rutgers University-Newark, is the author of “Building the Skyline: The Birth and Growth of Manhattan’s Skyscrapers.”

China’s booming electric vehicle market is about to run into a mountain of battery waste

China’s booming electric vehicle market is about to run into a mountain of battery waste. By Echo Huang
https://qz.com/1088195/chinas-booming-electric-vehicle-market-is-about-to-run-into-a-mountain-of-battery-waste/
Quartz, September 28, 2017

China’s push to promote electric cars comes with a lot of benefits for a country that suffers from terrible air pollution from its reliance on fossil fuels. But there’s always a downside—electric car batteries are toxic if not disposed of properly, and China’s on the verge of having to deal with a slew of batteries that can no longer hold a charge.

In just a few years, China has become the world’s biggest electric vehicle market, with the help of subsidies. It saw 336,00 new electric car registrations (pdf, p.12) in 2016, according to the International Energy Agency. That includes both battery-only and hybrid models. Including other types of vehicles, China says it sold a total of half a million “new energy” vehicles last year. This month, China also said that it would eventually phase out sales of all fossil-fuel cars.

That fast-growing market, however, is also producing batteries at a faster rate too. The average lifespan of a lithium-iron phosphate (LFP) battery, the dominant type in China’s electric vehicles, is around five years, according to Li Changdong, chairman of the Hunan-based Brunp group, China’s top electric car battery recycler in 2016 (link in Chinese). Most batteries installed on electric vehicles during the 2012 to 2014 period will be retired on a large scale (link in Chinese) around 2018, Li told the Beijing-based newspaper Economic Information Daily.

In 2020, nearly 250,000 metric tons (276,000 tons) of batteries, or 35 gigawatt-hours of batteries, are set to be retired—nearly 20 times those depleted in 2016, GaoGong Industry Institute, a Shenzhen-based electric car industry research firm, told Quartz.

[Unused batteries in China https://www.theatlas.com/charts/HJLUhCdjZ]


The battery is the heart of the electric vehicle industry, and the country needs a well-established battery recycling system, Xin Guobin, a top industry and tech official, told a national forum for the battery-powered engine industry Tuesday (link in Chinese) (Sept. 26). But recycling these batteries isn’t easy, due to the sophisticated chemical procedures involved. If it’s not done properly the heavy metal contained in the battery can lead to contamination of soil and water.

According to China’s 2015 electric vehicle battery policy, car manufacturers are responsible for recycling their batteries (link in Chinese). But many auto manufacturers often leave the responsibility to battery suppliers, who find it hard to afford the cost of building a national recycling network, noted the Economic Information Daily. For now, China’s battery recycling industry is relatively small and scattered, and recycling operating costs are high, Gao Xiaobing, director of the lithium battery study center at GaoGong, told Quartz. That’s discouraging more players from entering the business.

China’s not the only one facing a recycling headache. In the European Union, only 5% (pdf) of lithium-ion batteries, another common type of battery power used in electric vehicles are recycled, according to data from non-governmental environment advocacy group Friends of the Earth Europe, which pointed out that “most of the current lithium is either dumped in landfill or incinerated.”

Marriage Advantage in Subjective Well-Being: It Is Truly Protective

Marriage Advantage in Subjective Well-Being: Causal Effect or Unmeasured Heterogeneity? Alfred DeMaris. Marriage & Family Review, http://dx.doi.org/10.1080/01494929.2017.1359812

ABSTRACT: I investigate whether the marriage advantage in subjective well-being is a true protective effect vs. being attributable to self-selection into (or out of) marriage based on pre-existing mental health. I utilize 1,240 respondents from the GSS panel, a three-wave longitudinal survey collected from 2010–2014. I use a pseudo-treatment approach to informally test for the presence of self-selection. This is followed by a fixed-effect regression analysis to eliminate its influence when estimating the marriage effect. Results support the existence of self-selection: the currently married who in later waves will be exiting marriage are already more distressed than other married respondents in wave 1. And the currently not married who in later waves will be entering marriage are not more distressed in wave 1 than those remaining continuously married. A protective effect is also supported: at any given time, net of self-selection, the currently married are less distressed than the unmarried.

KEYWORDS: fixed effect regression, general social survey, longitudinal study, marriage, marriage advantage, subjective well-being


Check also: Types of intelligence predict likelihood to get married and stay married: Large-scale empirical evidence for evolutionary theory. Jaakko Aspara, Kristina Wittkowski, and Xueming Luo. Personality and Individual Differences, Volume 122, February 1 2018, Pages 1–6. http://www.bipartisanalliance.com/2017/10/types-of-intelligence-predict.html

Also: In Plain Sight: The Neglected Linkage between Brideprice and Violent Conflict. Valerie M. Hudson and Hilary Matfess. August 02, 2017. International Security, v 42 | Issue 1 | Summer 2017, p.7-40, doi: 10.1162/ISEC_a_00289. http://www.bipartisanalliance.com/2017/08/in-plain-sight-neglected-linkage.html

The High Cost of Good Intentions: A History of U.S. Federal Entitlement Programs, review by Tyler Cowen

*The High Cost of Good Intentions* by Tyler Cowen
http://marginalrevolution.com/marginalrevolution/2017/10/high-cost-good-intentions.html
Oct 14 2017

The subtitle is  A History of U.S. Federal Entitlement Programs, and the author of this new and excellent book is John F. Cogan of Stanford University and the Hoover Institution.  It is the single best history of what it covers, and thus one of the best books to read on the history of U.S. government or for that matter American economic history more generally.

How did the American entitlement state get built?  In multiple, discrete pieces:

The House and Senate overwhelmingly approved a modified version of President Truman's Social Security proposals in June 1950.  The Social Security Amendments provided a mammoth across-the-board increase in monthly benefits.  The law's sliding scale of benefits...averaged 77 percent per recipient...The 1950 Act also rewrote Social Security's eligibility rules to enable hundreds of thousands of workers with little history of contributing payroll taxes to begin collecting benefits.

And:

...from 1969 to 1975, inflation-adjusted federal entitlements pending grew annually at a remarkable 10 percent, registering an 86 percent increase in six years...Total annual inflation-adjusted entitlement expenditures grew 20 percent faster under President Nixon than they had under President Johnson.

And:

The eligibility liberalizations from 1997 to 2008 produced sharp increases in the food stamp and Medicaid rolls.  From 1998 to 2008, the food stamp rolls increased to 28 million people from 20 million and the Medicaid rolls increased to 59 million from 40 million people.  The liberalizations enacted during the Great Recession have lasted well beyond the recession's end in 2010.  In 2016, the number of food stamp recipients ballooned to 44 million, and the number of Medicaid recipients rose to 73 million in 2016.

Here is a good sentence:

In 2015, 41 percent of the nation's nonelderly-headed households received entitlement benefits.

This book is well-written and has useful and important information on virtually every page.

Exposure to Histological Stains Makes Abstract Art More Appealing

Taste in Art—Exposure to Histological Stains Shapes Abstract Art Preferences. Antonia M. Böthig, Gregor U. Hayn-Leichsenring. i-Perception,  Volume: 8 issue: 5. https://doi.org/10.1177/2041669517736073

Abstract: Exposure to art increases the appreciation of artworks. Here, we showed that this effect is domain independent. After viewing images of histological stains in a lecture, ratings increased for restricted subsets of abstract art images. In contrast, a lecture on art history generally enhanced ratings for all art images presented, while a lecture on town history without any visual stimuli did not increase the ratings. Therefore, we found a domain-independent exposure effect of images of histological stains to particular abstract paintings. This finding suggests that the ‘taste’ for abstract art is altered by visual impressions that are presented outside of an artistic context.

My commentary: Now I know whey I like to many forms of art... I see every day lots of filth, blood, pillaging, images of battered people, and very unclean pandhandlers, all sort of stains. To compensate so much violence against persons and my senses, I enjoy order, from Raffaello or any nederlander meester to current architecture, or disordered but beautiful aesthetics, like natural environments* or current painters.

* The Nature-Disorder Paradox: A Perceptual Study on How Nature Is Disorderly Yet Aesthetically Preferred. By Hiroki Kotabe, Omid Kardan & Marc Berman. Journal of Experimental Psychology: General, http://www.bipartisanalliance.com/2017/07/the-nature-disorder-paradox-perceptual.html

Candid photos made observers feel more connected to, more interested in getting to know or date, & like more the poster

A Candid Advantage? The Social Benefits of Candid Photos. Jonah Berger, Alixandra Barasch. Social Psychological and Personality Science, https://doi.org/10.1177/1948550617732390

Abstract: Photos are a ubiquitous mode of social communication. Analysis of thousands of online profiles finds that people overwhelmingly post posed photos of themselves. But might candids actually lead observers to react more favorably? Five studies test this possibility. Compared to posed photos, candids made observers feel more connected to the poster, feel more interested in getting to know or date them, and like them more. This was driven by candids making people seem more genuine, which made others react more favorably. Furthermore, consistent with the hypothesized role of genuineness, the benefits of candids were diminished when observers learned that the poster realized their photo was being taken. These finding highlight the role of authenticity in person perception and a potential disconnect between photo posters and viewers. Although posters seem to post mostly posed photos, observers may prefer candids because they provide a more authentic sense of who the poster really is.

Sharing of science is most likely among male scientists

Sharing of science is most likely among male scientists. Jorg J. M. Massen, Lisa Bauer, Benjamin Spurny, Thomas Bugnyar & Mariska E. Kret. Scientific Reports 7, Article number: 12927 (2017), doi:10.1038/s41598-017-13491-0

Abstract: Humans are considered to be highly prosocial, especially in comparison to other species. However, most tests of prosociality are conducted in highly artificial settings among anonymous participants. To gain a better understanding of how human hyper-cooperation may have evolved, we tested humans’ willingness to share in one of the most competitive fields of our current society: academia. Researchers were generally prosocial with 80% sharing a PDF of one of their latest papers, and almost 60% willing to send us their data. Intriguingly, prosociality was most prominent from male to male, and less likely among all other sex-combinations. This pattern suggests the presence of male-exclusive networks in science, and may be based on an evolutionary history promoting strong male bonds.

Bromance: More emotional stability, emotional disclosure, social fulfilment, & better conflict resolution, compared to emotional lives shared with girlfriends

Privileging the Bromance: A Critical Appraisal of Romantic and Bromantic Relationships. Stefan Robinson, Adam White, Eric Anderson. Men and Masculinities, https://doi.org/10.1177/1097184X17730386

Abstract: In this research, utilizing data from thirty semistructured interviews, we examine how heterosexual undergraduate men compare their experiences of bromances to that of their romantic relationships (romances). We find that the increasingly intimate, emotive, and trusting nature of bromances offers young men a new social space for emotional disclosure, outside of traditional heterosexual relationships. Participants state that the lack of boundaries and judgment in a bromance is expressed as emotionally rivalling the benefits of a heterosexual romance. Our participants mostly determined that a bromance offered them elevated emotional stability, enhanced emotional disclosure, social fulfilment, and better conflict resolution, compared to the emotional lives they shared with girlfriends. Thus, this research provides an empirically grounded conceptual framework for understanding men’s view of close homosocial relationships in comparison to their romantic relationship in the twenty-first century.

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Simplified: https://medicalxpress.com/news/2017-10-young-men-bromances-romances.html

Sex differences in empathy for pain: It seems there is no or very small role for autonomic regulation

Sex differences in empathy for pain: What is the role of autonomic regulation? Lincoln Tracy and Melita Giummarra. Psychophysiology, Volume 54, Issue 10, October 2017, Pages 1549–1558. https://doi.org/10.1111/psyp.12895

Abstract: Empathy involves both affective and cognitive components whereby we understand, and express concerns for, the experiences of others. Women typically have superior trait empathy compared with men, which seems to have a neurological basis with sex differences in the structure and function of neural networks involved in empathy. This study investigated sex differences in empathy for pain using the Empathy for Pain Scale, and examined whether these trait differences were associated with disruptions in autonomic regulation, specifically via the parasympathetic nervous system (measured through the square root of the mean squared differences of successive R-R intervals; RMSSD) both at rest and during a socioevaluative stress task (i.e., the serial sevens task). Compared with men, women reported higher empathic concern (Cohen's r = .25) and affective distress (Cohen's d = 0.65) toward another in pain. In both men and women, there was a decrease in lnRMSSD in the stress task compared to rest. Sex moderated the relationship between resting lnRMSSD and self-reported empathic concern. Specifically, there was no clear association between empathic concern and lnRMSSD in men whereas in women there was a negative relationship, with lower resting lnRMSSD associated with higher empathic concern, and higher lnRMSSD associated with lower levels of empathic concern that were similar to men. These findings suggest that empathic feelings may result from poorer psychophysiological regulation, and concur with previous research displaying sex-specific relationships between resting heart rate variability and emotion regulation abilities.

Some support for a sex, drugs, rock&roll connection, particularly among male performers & female listeners

Sex Drugs and Rock and Roll: Evidence Supporting the Storied Trilogy. Marissa A. Harrison & Susan M. Hughes. Human Ethology Bulletin, Volume 32, No 3, 63-84. https://doi.org/10.22330/heb/323/063-084

ABSTRACT: Sex, drugs, and rock and roll (SDRR) is a storied trilogy in popular culture. However, in scientific literature, there is little empirical evidence to determine if there is a positive relationship between these three phenomena, despite biological, psychological, and social reasons that would suggest they are connected. Via questionnaire, we asked participants to self-report alcohol and drug use, sexual behaviors and attitudes, and musical ability and preference. Although evidence was limited, there was some support for an SDRR connection, particularly among male performers and female listeners of rock and “harder” music. Interestingly, this mimics patterns of several bird species where males are the producers and females are the consumers of song. Ethological considerations and future directions are discussed.

Keywords: Rockmusic, birdsong, sex and drugs, substance use.

On Disease and Deontology -- Influence of Disease Threat on Moral Vigilance

On Disease and Deontology: Multiple Tests of the Influence of Disease Threat on Moral Vigilance. Damian Murray, Nicholas Kerry & Will Gervais. Social Psychological and Personality Science, https://doi.org/10.1177/1948550617733518

Abstract: Threat has been linked to certain facets of moral cognition, but the specific implications of disease threat for moral judgment remain poorly understood. Across three studies, we investigated the role of perceived disease threat in shaping moral judgment and hypothesized that perceived disease threat would cause people to be more sensitive to moral violations (or more “morally vigilant”). All three studies found a positive relationship between dispositional worry about disease transmission and moral vigilance. Additional analyses suggested that this worry was more strongly related to vigilance toward binding moral foundations. Study 3 demonstrated that moral vigilance was higher in individuals for whom the threat of disease was experimentally made salient, relative to individuals in both a neutral and a nondisease threat condition. Taken together, these results suggest that perceived disease threat may influence people’s moral vigilance across moral domains.

My comment: The Conservatives are a bore, but are not stupid. They are more empirical than Progressives, and many of their obsessions (security/defense, religion/morality, and maybe patriotism) have perfectly normal motivations, not only instincts/genetic programming. Progressives should try to understand better Conservatives (and viceversa, obviously :-) ).

Prejudice Reduction: What Works? A Review and Assessment of Research and Practice

Prejudice Reduction: What Works? A Review and Assessment of Research and Practice. Elizabeth Levy Paluck and Donald P. Green. Annu. Rev. Psychol. 2009. 60:339–67. 10.1146/annurev.psych.60.110707.163607
https://www.cscc.edu/about/faculty/pd/files/Paluck%20-%20Prejudice%20Reduction.pdf

Abstract: This article reviews the observational, laboratory, and field experimental literatures on interventions for reducing prejudice. Our review places special emphasis on assessing the methodological rigor of existing research, calling attention to problems of design and measurement that threaten both internal and external validity. Of the hundreds of studies we examine, a small fraction speak convincingly to the questions of whether, why, and under what conditions a given type of intervention works. We conclude that the causal effects of many widespread prejudice-reduction interventions, such as workplace diversity training and media campaigns, remain unknown. Although some intergroup contact and cooperation interventions appear promising, a much more rigorous and broad-ranging empirical assessment of prejudice-reduction strategies is needed to determine what works.

Key Words: field experiments, evaluation, stereotype reduction, cooperative learning, contact hypothesis, peace education, media and reading interventions, diversity training, cultural competence, multicultural education, antibias education, sensitivity training, cognitive training

Rolling out the most comprehensive social control -- China to create national name-and-shame system for ‘deadbeat borrowers’

China to create national name-and-shame system for ‘deadbeat borrowers’

By He Huifeng
South China Morning Post. Tuesday, October 10, 2017
Anyone who fails to repay a bank loan will be blacklisted and have their personal details made public

http://www.scmp.com/news/china/economy/article/2114768/china-create-national-name-and-shame-system-deadbeat-borrowers
 
Those who fail to repay a bank loan will be blacklisted, and they will have their name, ID number, photograph, home address and the amount they owe published or announced through various channels – including in newspapers, online, on radio and television, and on screens in buses and public lifts.

[...]In the southern city of Guangzhou, the personal details of some 141 debt defaulters have so far been displayed on screens in buses, commercial buildings and on media platforms at the request of local courts.

Meanwhile in Jiangsu, Henan and Sichuan provinces, the courts have teamed up with telecoms operators to create a recorded message – played every time someone calls – for those who fail to repay their loans. The message tells the caller: “The person you are calling has been put on a blacklist by the courts for failing to repay their debts. Please urge this person to honour their legal obligations.”   

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Check this: China’s New Tool for Social Control: A Credit Rating for Everything. By Josh Chin and Gillian Wong
http://www.bipartisanalliance.com/2017/08/chinas-tool-for-social-control-credit.html

Beijing wants to give every citizen a score based on behavior such as spending habits, turnstile violations and filial piety, which can blacklist citizens from loans, jobs, air travel
WSJ, Nov. 28, 2016

Having more Neanderthal genes favor having social fear, autistic tendencies, and depressive tendencies

Using Personal Genome Technology and Psychometrics to Study the Personality of the Neanderthals. Glenn Geher, Richard Holler, David Chapleau, Jessica Fell, Bernadine Gangemi, Morgan Gleason, Vania Rolon, Andrew Shimkus & Briana Tauber. Human Ethology Bulletin, Volume 32, No 3, 34-46, DOI:  https://doi.org/10.22330/heb/323/034-046

ABSTRACT: The Neanderthals’ extinction has been, according to modern biological anthropologists, greatly exaggerated. Research from multiple sources has consistently provided strong evidence of hybridization between ancestral Neanderthals and Ancestrally Modern Humans (AMHs). Personal genome technology, such as that used by the personal-genomic company, 23andMe, provides individuals with information regarding their particular genetic overlap with Neanderthal DNA. Given the fact that most personality traits show some heritable component, this research sought to examine if one’s degree of Neanderthal genetic overlap (or Neanderthal Quotient; NQ) is significantly related to a variety of personality traits – traits that, based on anthropological research – may have characterized our ancient Neanderthal cousins. Using an online survey administered to more than 200 adults from around the world who had had their personal genomes mapped, we found that NQ was positively related to such variables as social fear, anxiety, and promiscuity, while being negatively related to scores on a performance-based measure of imaginativeness. Most of these relationships remained significant in regression models that added age and gender into the equations, suggesting that these findings are likely relatively reliable. Findings suggest that high levels of NQ tend to correspond to social fear, autistic tendencies, and depressive tendencies – a constellation of results that is consistent with the conception of Neanderthals as being ill-suited for large-scale social living.

Keywords: Neanderthal, personality, personal genome, social anxiety, fear, sociosexuality.

Song practice as a rewarding form of play in songbirds, correlating with opioid and endocannabinoid markers in the brain

Song practice as a rewarding form of play in songbirds. Lauren V. Riters et al. Behavioural Processes, https://doi.org/10.1016/j.beproc.2017.10.002

Highlights
•    To use song effectively in reproductive contexts, songbirds must practice singing.
•    Song practice is associated with positive affect and activity in reward systems.
•    Song practice correlates with opioid and endocannabinoid markers in the brain.
•    Multiple aspects of play behavior parallel what is observed for song practice.
•    Song practice may be considered a rewarding form of play behavior.

Abstract: In adult songbirds, the primary functions of song are mate attraction and territory defense; yet, many songbirds sing at high rates as juveniles and outside these primary contexts as adults. Singing outside primary contexts is critical for song learning and maintenance, and ultimately necessary for breeding success. However, this type of singing (i.e., song “practice”) occurs even in the absence of immediate or obvious extrinsic reinforcement; that is, it does not attract mates or repel competitors. Here we review studies that support the hypothesis that song practice is stimulated and maintained by intrinsic reward mechanisms (i.e., that it is associated with a positive affective state). Additionally, we propose that song practice can be considered a rewarding form of play behavior similar to forms of play observed in multiple young animals as they practice sequences of motor events that are used later in primary adult reproductive contexts. This review highlights research suggesting at least partially overlapping roles for neural reward systems in birdsong and mammalian play and evidence that steroid hormones modify these systems to shift animals from periods of intrinsically rewarded motor exploration (i.e., singing in birds and play in mammals) to the use of similar motor patterns in primary reproductive contexts.

Keywords: Communication; Endocannabinoids; Learning; Opioids; Reward