Since the late nineteenth century, cultural historians have noted that the importance of love increased during the Medieval and Early Modern European period (a phenomenon that was once referred to as the emergence of ‘courtly love’). However, more recent works have shown a similar increase in Chinese, Arabic, Persian, Indian and Japanese cultures. Why such a convergent evolution in very different cultures? Using qualitative and quantitative approaches, we leverage literary history and build a database of ancient literary fiction for 19 geographical areas and 77 historical periods covering 3,800 years, from the Middle Bronze Age to the Early Modern period. We first confirm that romantic elements have increased in Eurasian literary fiction over the past millennium, and that similar increases also occurred earlier, in Ancient Greece, Rome and Classical India. We then explore the ecological determinants of this increase. Consistent with hypotheses from cultural history and behavioural ecology, we show that a higher level of economic development is strongly associated with a greater incidence of love in narrative fiction (our proxy for the importance of love in a culture). To further test the causal role of economic development, we used a difference-in-difference method that exploits exogenous regional variations in economic development resulting from the adoption of the heavy plough in medieval Europe. Finally, we used probabilistic generative models to reconstruct the latent evolution of love and to assess the respective role of cultural diffusion and economic development.
Thursday, April 28, 2022
Tuesday, April 26, 2022
Below, I am passing on some links to background reading for this Sunday's Austin Rainbow Forum (email firstname.lastname@example.org for information), whose discussion topic is "The War in Ukraine: Start of World War III?."
David Brooks - Globalization Is Over. The Global Culture Wars Have Begun
Thomas Friedman - Putin Had No Clue How Many of Us Would Be Watching
Yuval Harari - What’s at stake in Ukraine is the direction of human history
Thursday, April 21, 2022
The story of Babel is the best metaphor I have found for what happened to America in the 2010s, and for the fractured country we now inhabit. Something went terribly wrong, very suddenly. We are disoriented, unable to speak the same language or recognize the same truth. We are cut off from one another and from the past.
It’s been clear for quite a while now that red America and blue America are becoming like two different countries claiming the same territory, with two different versions of the Constitution, economics, and American history. But Babel is not a story about tribalism; it’s a story about the fragmentation of everything. It’s about the shattering of all that had seemed solid, the scattering of people who had been a community. It’s a metaphor for what is happening not only between red and blue, but within the left and within the right, as well as within universities, companies, professional associations, museums, and even families.
Babel is a metaphor for what some forms of social media have done to nearly all of the groups and institutions most important to the country’s future—and to us as a people. How did this happen? And what does it portend for American life?
Monday, April 18, 2022
The mammalian gastrointestinal tract hosts a community of diverse micro-organisms, including bacteria, archea, fungi, and viruses. Bacterial products, such as metabolites and cell wall fragments, are implicated in host metabolic functions. In addition, the gut microbiota influences the immune and central nervous systems, and it has emerged as a key regulator of brain development and the modulation of behaviors, including stress and anxiety, often in a sex-specific manner. Disruption of gut microbiota–brain interactions contribute to the pathogenesis of neurodevelopmental and psychiatric disorders in animal models. ...Gabanyi et al. show that bacterial peptidoglycans, a by-product of bacterial cell wall degradation during cell division and cell death, directly inhibit the activity of feeding-promoting neurons in the hypothalamus and ultimately decrease appetite and body temperature, mostly in female mice. This finding may open new approaches for the treatment of metabolic disorders, including obesity.
Friday, April 15, 2022
I can remember a time — about a quarter-century ago — when the world seemed to be coming together. The great Cold War contest between communism and capitalism appeared to be over. Democracy was still spreading. Nations were becoming more economically interdependent. The internet seemed ready to foster worldwide communications. It seemed as if there would be a global convergence around a set of universal values — freedom, equality, personal dignity, pluralism, human rights...it was sometimes assumed that nations all around the world would admire the success of the Western democracies and seek to imitate us...They’d be more driven by the desire to settle down into suburban homes than by the fanatical ideologies or the sort of hunger for prestige and conquest that had doomed humanity to centuries of war.
...this vision does not describe the world we live in today. The world is not converging anymore; it’s diverging...The 2008 financial crisis delegitimized global capitalism for many people...Global flows of long-term investment fell by half between 2016 and 2019...All manner of antiglobalization movements have arisen: those of the Brexiteers, xenophobic nationalists, Trumpian populists, the antiglobalist left...The world economy seems to be gradually decoupling into, for starters, a Western zone and a Chinese zone. Foreign direct investment flows between China and America were nearly $30 billion per year five years ago. Now they are down to $5 billion...Economic rivalries have now merged with political, moral and other rivalries into one global contest for dominance. Globalization has been replaced by something that looks a lot like global culture war.
The fact is that human behavior is often driven by forces much deeper than economic and political self-interest, at least as Western rationalists typically understand these things...First, human beings are powerfully driven by what are known as the thymotic desires. These are the needs to be seen, respected, appreciated. If you give people the impression that they are unseen, disrespected and unappreciated, they will become enraged, resentful and vengeful. They will perceive diminishment as injustice and respond with aggressive indignation...Global politics over the past few decades functioned as a massive social inequality machine. In country after country, groups of highly educated urban elites have arisen to dominate media, universities, culture and often political power. Great swaths of people feel looked down upon and ignored.
Second, most people have a strong loyalty to their place and to their nation. But over the past few decades many people have felt that their places have been left behind and that their national honor has been threatened. In the heyday of globalization, multilateral organizations and global corporations seemed to be eclipsing nation-states...In country after country, highly nationalistic movements have arisen to insist on national sovereignty and to restore national pride: Modi in India, Recep Tayyip Erdogan in Turkey, Trump in the United States, Boris Johnson in Britain.
Third, people are driven by moral longings — by their attachment to their own cultural values, by their desire to fiercely defend their values when they seem to be under assault. For the past few decades, globalization has seemed to many people to be exactly this kind of assault...The problem is that Western values are not the world’s values. In fact, we in the West are complete cultural outliers. In his book “The WEIRDest People in the World,” Joseph Henrich amasses hundreds of pages of data to show just how unusual Western, Educated, Industrialized, Rich and Democratic values are...Many people around the world look at our ideas about gender roles and find them foreign or repellent...The idea that it’s up to each person to choose one’s own identity and values — that seems ridiculous to many. The idea that the purpose of education is to inculcate critical thinking skills so students can liberate themselves from the ideas they received from their parents and communities — that seems foolish to many.
Finally, people are powerfully driven by a desire for order. Nothing is worse than chaos and anarchy...Today, many democracies appear less stable than they did and many authoritarian regimes appear more stable. American democracy, for example, has slid toward polarization and dysfunction. Meanwhile, China has shown that highly centralized nations can be just as technologically advanced as the West. Modern authoritarian nations now have technologies that allow them to exercise pervasive control of their citizens in ways that were unimaginable decades ago...Autocratic regimes are now serious economic rivals to the West. They account for 60 percent of patent applications. In 2020, the governments and businesses in these countries invested $9 trillion in things like machinery, equipment and infrastructure, while democratic nations invested $12 trillion. If things are going well, authoritarian governments can enjoy surprising popular support.
...something bigger is happening today that is different from the great power struggles of the past, that is different from the Cold War. This is not just a political or an economic conflict. It’s a conflict about politics, economics, culture, status, psychology, morality and religion all at once. More specifically, it’s a rejection of Western ways of doing things by hundreds of millions of people along a wide array of fronts...To define this conflict most generously, I’d say it’s the difference between the West’s emphasis on personal dignity and much of the rest of the world’s emphasis on communal cohesion. But that’s not all that’s going on here. What’s important is the way these longstanding and normal cultural differences are being whipped up by autocrats who want to expand their power and sow chaos in the democratic world. Authoritarian rulers now routinely weaponize cultural differences, religious tensions and status resentments to mobilize supporters, attract allies and expand their own power. This is cultural difference transmogrified by status resentment into culture war.
...rejection of Western liberalism, individualism, pluralism, gender equality and all the rest is not only happening between nations but also within nations. The status resentment against Western cultural, economic and political elites that flows from the mouths of illiberal leaders like Putin and Modi and Jair Bolsonaro of Brazil sounds quite a lot like the status resentment that flows from the mouths of the Trumpian right, from the French right, from the Italian and Hungarian right...How do you win a global culture war in which differing views on secularism and gay rights parades are intertwined with nuclear weapons, global trade flows, status resentments, toxic masculinity and authoritarian power grabs?
The critiques that so many people are making about the West, and about American culture — for being too individualistic, too materialistic, too condescending — these critiques are not wrong. We have a lot of work to do if we are going to be socially strong enough to stand up to the challenges that are coming over the next several years, if we are going to persuade people in all those swing countries across Africa, Latin America and the rest of the world that they should throw their lot in with the democracies and not with the authoritarians — that our way of life is the better way of life.
At the end of the day, only democracy and liberalism are based on respect for the dignity of each person. At the end of the day, only these systems and our worldviews offer the highest fulfillment for the drives and desires I’ve tried to describe here...I have faith in the ideas and the moral systems that we have inherited. What we call “the West” is not an ethnic designation or an elitist country club. The heroes of Ukraine are showing that at its best, it is a moral accomplishment, and unlike its rivals, it aspires to extend dignity, human rights and self-determination to all. That’s worth reforming and working on and defending and sharing in the decades ahead.
Wednesday, April 13, 2022
Sleep and wakefulness are characterized by unique intrinsic activity patterns and are usually thought to be two distinct global states, with the preoptic area of the hypothalamus being the regulator of brain state changes. Yamagata et al. find that this area also affects within-state changes of sleep and wake intensity.
Our current understanding of how sleep is regulated is based upon the model of sleep homeostasis, which defines a variable called Process S as a measure of sleep need, and a so-called “flip-flop” model of state switching, which builds on a notion of a mutually antagonistic relationship between subcortical sleep-promoting and wake-promoting circuits. The neurobiological substrates of the interaction between the sleep switch and Process S are unknown. Our study identifies a previously unrecognized role of hypothalamic circuitry in tuning within-state brain activity or levels of arousal, which in turn determine the homeostatic drive for sleep.Abstract
Sleep and wakefulness are not simple, homogenous all-or-none states but represent a spectrum of substates, distinguished by behavior, levels of arousal, and brain activity at the local and global levels. Until now, the role of the hypothalamic circuitry in sleep–wake control was studied primarily with respect to its contribution to rapid state transitions. In contrast, whether the hypothalamus modulates within-state dynamics (state “quality”) and the functional significance thereof remains unexplored. Here, we show that photoactivation of inhibitory neurons in the lateral preoptic area (LPO) of the hypothalamus of adult male and female laboratory mice does not merely trigger awakening from sleep, but the resulting awake state is also characterized by an activated electroencephalogram (EEG) pattern, suggesting increased levels of arousal. This was associated with a faster build-up of sleep pressure, as reflected in higher EEG slow-wave activity (SWA) during subsequent sleep. In contrast, photoinhibition of inhibitory LPO neurons did not result in changes in vigilance states but was associated with persistently increased EEG SWA during spontaneous sleep. These findings suggest a role of the LPO in regulating arousal levels, which we propose as a key variable shaping the daily architecture of sleep–wake states.
Monday, April 11, 2022
Mammals are the most encephalized vertebrates, with the largest brains relative to body size. Placental mammals have particularly enlarged brains, with expanded neocortices for sensory integration, the origins of which are unclear. We used computed tomography scans of newly discovered Paleocene fossils to show that contrary to the convention that mammal brains have steadily enlarged over time, early placentals initially decreased their relative brain sizes because body mass increased at a faster rate. Later in the Eocene, multiple crown lineages independently acquired highly encephalized brains through marked growth in sensory regions. We argue that the placental radiation initially emphasized increases in body size as extinction survivors filled vacant niches. Brains eventually became larger as ecosystems saturated and competition intensified.
Friday, April 08, 2022
...highlight a deeper point: Humans don’t have culture because we’re smart, we’re smart because we have culture. The selective processes of cultural evolution not only generate more sophisticated practices and technologies but also produce new cognitive tools—algorithms—that make humans better adapted to the ecological and institutional challenges that we confront. Thompson et al.’s results underline the need for the psychological sciences to abandon their implicit reliance on a digital computer metaphor of the mind (hardware versus software) and transform into a historical science that considers not just how cultural evolution shapes what we think (our mental contents) but also how we think [our cognitive processes].Here I pass on the introductory paragraphs and then the abstract of the Thompson et al. article. Motivated readers can obtain the full text by emailing me.
Reading, counting, cooking, and sailing are just some of the human abilities passed from generation to generation through social learning... Complex abilities like these often depend on learned cognitive algorithms: procedural representations of a problem that coordinate memory, attention, and perception into sequences of useful computations and actions. Accumulation of complex algorithms—from ancient tool-making techniques to bread making, boat building, or horticulture—is central to human adaptation yet challenging to explain because algorithmic concepts can be difficult to discover, communicate, and learn from observation, making them vulnerable to loss. Theories of cultural evolution suggest that human social learning may help overcome this fragility. For example, mathematical models predict that choosing to learn from successful or prestigious individuals can prevent the loss of rare innovations. However, this potential link between sociality and complex abilities is challenging to establish.
We conducted large-scale simulations of cultural evolution with human participants to assess how selective social learning influenced the evolution of cognitive algorithms. Prior research shows that social learning can improve decisions in multiple-choice tasks, perceptual judgments, and search problems and can improve artifacts such as physical structures or computer programs. However, the evolution of cognitive algorithms at the population level has been difficult to study. We developed custom software to recruit large numbers of participants online and organize them into evolving societies facing a common problem. Twenty populations tackled a sequential decision problem... Presented with six images, participants attempted to establish hidden arbitrary orderings using pairwise comparisons. Out-of-order pairs swapped positions when compared. Participants were rewarded for establishing the ordering using fewer comparisons. This task poses a sorting problem, requiring a strategy for executing appropriate sequences of actions, analogous to culturally evolved strategies for making tools or food.Abstract:
Many human abilities rely on cognitive algorithms discovered by previous generations. Cultural accumulation of innovative algorithms is hard to explain because complex concepts are difficult to pass on. We found that selective social learning preserved rare discoveries of exceptional algorithms in a large experimental simulation of cultural evolution. Participants (N = 3450) faced a difficult sequential decision problem (sorting an unknown sequence of numbers) and transmitted solutions across 12 generations in 20 populations. Several known sorting algorithms were discovered. Complex algorithms persisted when participants could choose who to learn from but frequently became extinct in populations lacking this selection process, converging on highly transmissible lower-performance algorithms. These results provide experimental evidence for hypothesized links between sociality and cognitive function in humans.
Wednesday, April 06, 2022
Monday, April 04, 2022
Friday, April 01, 2022
Humans spend approximately one-third of their lives asleep, but this is not distributed equally across their life span. Sleep quantity and quality decline as age advances, and insomnia and sleep fractionation are common in older people. Sleep is essential for vitality and health. At any age, chronic sleep deprivation causes a range of issues, including disrupted cognition and memory. Correspondingly, sleep complaints in older people are associated with increased risks of impaired physical and mental health and with mortality. Beyond evidence of degenerating subcortical nuclei in age-associated sleep disturbances, the underlying mechanisms remain unclear despite decades of awareness of the problem and its consequences...Li et al.report the hyperexcitability of hypocretin neurons as a core mechanism underlying sleep disruption in aged mice, explaining why sleep is punctuated by intruding wakefulness despite the loss of wake-promoting neurons.
A few clips from the Li et al. article:
We hypothesized that the decline in sleep quality could be due to malfunction of the neural circuits associated with sleep/wake control. It has been established that hypocretin/orexin (Hcrt/OX) neuronal activity is tightly associated with wakefulness and initiates and maintains the wake state. In this study, we investigated whether the intrinsic excitability of Hcrt neurons is altered, leading to a destabilized control of sleep/wake states during aging.RESULTS
Aged mice exhibited sleep fragmentation and a significant loss of Hcrt neurons. Hcrt neurons manifested a more frequent firing pattern, driving wake bouts and disrupting sleep continuity in aged mice. Aged Hcrt neurons were capable of eliciting more prolonged wake bouts upon optogenetic stimulations. These results suggested that hyperexcitability of Hcrt neurons emerges with age. Patch clamp recording in genetically identified Hcrt neurons revealed distinct intrinsic properties between the young and aged groups. Aged Hcrt neurons were hyperexcitable with depolarized membrane potentials (RMPs) and a smaller difference between RMP and the firing threshold.CONCLUSION
Aged mice exhibited sleep fragmentation and a significant loss of Hcrt neurons. Hcrt neurons manifested a more frequent firing pattern, driving wake bouts and disrupting sleep continuity in aged mice. Aged Hcrt neurons were capable of eliciting more prolonged wake bouts upon optogenetic stimulations. These results suggested that hyperexcitability of Hcrt neurons emerges with age. Patch clamp recording in genetically identified Hcrt neurons revealed distinct intrinsic properties between the young and aged groups. Aged Hcrt neurons were hyperexcitable with depolarized membrane potentials (RMPs) and a smaller difference between RMP and the firing threshold.