Wednesday Round Up #19

The Consciousness and Metacognition YouTube Channel

Here’s one, a general overview of why understanding the brain can be useful to different people, from researchers to social workers.
Introduction to Brain and Consciousness 0.1 – Understanding Mental Health at Different Levels:

How to Write an Essay: A Guide for Anthropologists

There are two things you must know intimately before you start: your audience and your core point. Know these things and the rest will be far easier. Once you have locked down those two core elements, there’s a basic formula that you can master for almost any essay.

What Strength Really Means When You’re Sick

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Manipulating student evaluations: the Downey Sales School method

Student evaluations are biased? Yes, yes, they are. Research has repeatedly shown that students’ evaluations of teaching quality show a range of biases. For example, Anne BoringKellie Ottoboni and Philip B. Stark argue on the LSE’s Impact blog that:

Student evaluations of teaching (SET) are strongly associated with the gender of the instructor. Female instructors receive lower scores than male instructors. SET are also significantly correlated with students’ grade expectations: students who expect to get higher grades give higher SET, on average. But SET are not strongly associated with learning outcomes.

Even given their limitations and outright unfairness, universities are not likely to give up student evaluations soon.

So I offer you another alternative: How I manipulate student evaluation scores. Using techniques I first learned while a door-to-door salesman as an undergraduate, here are tried and tested techniques for improving your evaluations, from the keyboard of a 25+ year university veteran. Buckle up — this may sound cynical — but I hope to persuade you that my goals and methods are not only ethical, but actually might improve your teaching. 

Photo by Aldiyar Seitkassymov on
Continue reading “Manipulating student evaluations: the Downey Sales School method”

Wednesday Round Up #18

This Overlooked Variable Is the Key to the Pandemic

There are COVID-19 incidents in which a single person likely infected 80 percent or more of the people in the room in just a few hours. But, at other times, COVID-19 can be surprisingly much less contagious. Overdispersion and super-spreading of this virus are found in research across the globe. A growing number of studies estimate that a majority of infected people may not infect a single other person. A recent paper found that in Hong Kong, which had extensive testing and contact tracing, about 19 percent of cases were responsible for 80 percent of transmission, while 69 percent of cases did not infect another person. This finding is not rare: Multiple studies from the beginning have suggested that as few as 10 to 20 percent of infected people may be responsible for as much as 80 to 90 percent of transmission, and that many people barely transmit it.

This highly skewed, imbalanced distribution means that an early run of bad luck with a few super-spreading events, or clusters, can produce dramatically different outcomes even for otherwise similar countries… This kind of behavior, alternating between being super infectious and fairly noninfectious, is exactly what k captures, and what focusing solely on R hides.

Few people knew female birds had unique songs—until women started studying them

Recent findings have shown that female song is widespread, and it is likely that the ancestor of all songbirds had female song. Now, rather than asking why males originally evolved song, the question has become why both sexes originally evolved song, and why females have lost song in some species.

In a recently published study, we reviewed 20 years of research on female bird song and found that the key people driving this recent paradigm shift were women. If fewer women had entered this field, we believe that it likely would have taken much longer to reach this new understanding of how bird song originally evolved. We see this example as a powerful demonstration of why it’s important to increase diversity in all fields of science.

The End of Art History

Karmel has, in fact, proven that a global history of abstraction is impossible. This is an important achievement, for it opens the way to constructive analysis. Today’s art world has an essentially different structure from Gombrich’s Eurocentric tradition or Clement Greenberg’s New York-centric era; we must now recognize that writing a global art history demands that we give up historical thinking.

The Science of Stress and How Our Emotions Affect Our Susceptibility to Burnout and Disease

Memory, it turns out, is one of the major factors mediating the dialogue between sensation and emotional experience. Our memories of past experience become encoded into triggers that act as switchers on the rail of psychoemotional response, directing the incoming train of present experience in the direction of one emotional destination or another.

Why the right wing has a massive advantage on Facebook
*A better title for this piece would be that Facebook recognizes that it’s a company who manipulates emotions, creates excessive engagement, and promotes knee-jerk responding. It’s their business model. They are literally now the Tabloid of the Internt.

“Right-wing populism is always more engaging,” a Facebook executive said in a recent interview with POLITICO reporters, when pressed why the pages of conservatives drive such high interactions. The person said the content speaks to “an incredibly strong, primitive emotion” by touching on such topics as “nation, protection, the other, anger, fear.”

“That was there in the [19]30’s. That’s not invented by social media — you just see those reflexes mirrored in social media, they’re not created by social media,” the executive added. “It’s why tabloids do better than the [Financial Times], and it’s also a human thing. People respond to engaging emotion much more than they do to, you know, dry coverage. …This wasn’t invented 15 years ago when Mark Zuckerberg started Facebook.”

Your Brain Chooses What to Let You See

Take a counterintuitive finding that Tadin and his colleagues made in 2003: We’re good at perceiving the movements of small objects, but if those objects are simply made bigger, we find it much more difficult to detect their motion.

Recently in Nature Communications, Tadin’s team offered a tantalizing explanation for why this happens: The brain prioritizes the detection of objects that are more important for us to see, and those tend to be smaller. To a hawk hunting for its next meal, a mouse suddenly darting through a field matters more than the swaying motion of the grass and trees around it. As a result, Tadin and his team discovered, the brain suppresses information about the movement of the background — and as a side effect, it has more difficulty perceiving the movements of larger objects, because it treats them as a kind of background, too.

Wednesday Round Up #17

How the Brain Creates a Timeline of the Past

They came up with equations to describe how the brain might in theory encode time indirectly. In their scheme, as sensory neurons fire in response to an unfolding event, the brain maps the temporal component of that activity to some intermediate representation of the experience — a Laplace transform, in mathematical terms. That representation allows the brain to preserve information about the event as a function of some variable it can encode rather than as a function of time (which it can’t). The brain can then map the intermediate representation back into other activity for a temporal experience — an inverse Laplace transform — to reconstruct a compressed record of what happened when.

Just a few months after Howard and Shankar started to flesh out their theory, other scientists independently uncovered neurons, dubbed “time cells,” that were “as close as we can possibly get to having that explicit record of the past,” Howard said. These cells were each tuned to certain points in a span of time, with some firing, say, one second after a stimulus and others after five seconds, essentially bridging time gaps between experiences.

The Simple Algorithm That Ants Use to Build Bridges

The cost, ecologists think, is that ants trapped in bridges aren’t available for other tasks, like foraging. At any time on a march, a colony might be maintaining 40 to 50 bridges, with as few as one and as many as 50 ants per bridge. In a 2015 paper, Garnier and his colleagues calculated that as much as 20 percent of the colony can be locked into bridges at a time. At this point, a shorter route just isn’t worth the extra ants it would take to create a longer bridge.

Except, of course, individual ants have no idea how many of their colony-mates are holding fast over a gap. And this is where the second rule kicks in. As individual ants run the “bridging” algorithm, they have a sensitivity to being stampeded. When traffic over their backs is above a certain level, they hold in place, but when it dips below some threshold — perhaps because too many other ants are now occupied in bridge-building themselves — the ant unfreezes and rejoins the march.

The Dying Russians

In the seventeen years between 1992 and 2009, the Russian population declined by almost seven million people, or nearly 5 percent—a rate of loss unheard of in Europe since World War II. Moreover, much of this appears to be caused by rising mortality. By the mid-1990s, the average St. Petersburg man lived for seven fewer years than he did at the end of the Communist period; in Moscow, the dip was even greater, with death coming nearly eight years sooner.

In 2006 and 2007, Michelle Parsons, an anthropologist who teaches at Emory University and had lived in Russia during the height of the population decline in the early 1990s, set out to explore what she calls “the cultural context of the Russian mortality crisis.” Her method was a series of long unstructured interviews with average Muscovites—what amounted to immersing herself in a months-long conversation about what made life, for so many, no longer worth living. The explanation that Parsons believes she has found is in the title of her 2014 book, Dying Unneeded.

Is Freedom White?

In a political season of dog whistles, we must be attentive to how talk of American freedom has long been connected to the presumed right of whites to dominate everyone else.

“Segregation now, segregation tomorrow, segregation forever!” Alabama governor George Wallace’s most famous sentence fired through the frigid air on the coldest day anyone in the state could remember. His 1963 inaugural address—written by a Klansman, no less—served as the war cry for the massive, violent response to the nonviolent civil rights movements of the 1960s. Wallace’s brand of right-wing populism would reconfigure U.S. party politics, making him, as his biographer put it, the “invisible founding father” of modern conservatism. As so many pundits have pointed out, when Donald Trump talks about “domination” today, he is talking the language and politics of Wallace.

Yet Wallace’s famous speech was less about segregation than it was about freedom—white freedom. Other than its infamous applause line, the inaugural mentions “segregation” only one other time. In contrast, it invokes “freedom” twenty-four times—more times than Martin Luther King, Jr., used the word during his “I Have a Dream” address the following summer at the 1963 March on Washington. Freedom is this nation’s ill-defined but reflexive ideological commitment. Winding through the heart of that complex political idea, however, is a dark and visceral current of freedom as the unrestrained capacity to dominate.

The Tyranny of Fragility: How Alexis De Tocqueville Foretold the Rise of Victimhood Culture

Tocqueville’s writings illuminate a deep paradox arising from modern forms of democracy—as is evident in common misconceptions of his critique of the tyranny of the majority. For Tocqueville, the real tyrant in democracy is not so much the group as the individual; or rather individualism as we know it—entitled, selfish, envious, consumerist, insatiable—which arises when certain conditions of collectivist populism are in place. The erosion of extended kinship structures, religion and broader systems of ritual and meaning—which afford both a source of support and a sense of duty to others and to a project greater than oneself—are certainly partly to blame.

But Tocqueville also directs our attention to the most perverse level at which modern individuation operates: that of what becomes imaginable, desirable but ultimately unattainable in the democracy of the masses. You might call this the cognitive-affective dimension of democracy. Once a certain ideal of equality—however ill-defined as a normative goal—is in place, envy and upward social comparison become the norm. Since anyone can become more of anything or anyone at any time, something akin to entropy increases. In affective terms, social and psychological entropy become something we now call anxiety.

Talking Is Throwing Fictional Worlds at One Another

There’s an interesting paradox in Language Unlimited. You write that language is endlessly creative but also our cognition is constrained by the structure of language. What does that paradox say about human beings?

You’re right. There is a wee paradox in there. That’s a nice thing to pick up on. I think about it like even numbers. There’s an unlimited number of even numbers but obviously they’re limited, right? Because 3s and 7s aren’t in there. Language is like that. There’s an unlimited number of possible things we can say, of sentence structures, but not anything can be a sentence structure.

So you’re absolutely right. Language is unlimited, but it’s unlimited in a limited way.

What does that say about us as human beings? That’s a gigantic and fascinating question. It probably means our cognition is limited. There may be things that we can never solve because we don’t have the cognitive structures that will help to solve them.

LOL Something Matters

These lamentations continued unabated throughout 2017. Just two weeks ago, Facebook said it would no longer flag phony links with red-box warnings, since pointing to a lie only makes it stronger. The truth, this move implied, does more harm than good.

But there’s a problem with these stories about the end of facts. In the past few years, social scientists armed with better research methods have been revisiting some classic work on the science of post-truth. Based on their results, the most surprising and important revelations from this research—the real lol-nothing-matters stuff—now seem overstated. It may be that the internet does not divide us, that facts don’t make us dumber than we were before, and that debunking doesn’t really lead to further bunk.

In fact, it may be time that we gave up on the truth-y notion that we’re living in a post-truth age. In fact, it may be time that we debunked the whole idea.

The Final Five Percent

If traumatic brain injuries can impact the parts of the brain responsible for personality, judgment, and impulse control, maybe injury should be a mitigating factor in criminal trials — but one neuroscientist discovers that assigning crime a biological basis creates more issues than it solves.

7 Modern Life Habits That Can Be Incredibly Bad For Your Brain Health

“In our study, socializing was just as effective as more traditional kinds of mental exercise in boosting memory and intellectual performance,” said Oscar Ybarra, a psychologist at the U-M Institute for Social Research (ISR) and a lead author of the study with ISR psychologist Eugene Burnstein and psychologist Piotr Winkielman from the University of California, San Diego.

The lack of true personal interaction limits the brain’s opportunities to make better connections. It can also lead to loneliness and depression — mental conditions that contribute significantly to reduced brain health.

Wednesday Round Up #16

My Octopus Teacher

Gordon W. Hewes — a four-field anthropologist with an encyclopedic, visual sensibility. He was interdisciplinary before it was cool.

There’s No Homunculus In Our Brain Who Guides Us

The cognitive-map theory has inspired decades of experiments and become a ubiquitous and widely used concept. Edward Tolman, a professor at the University of California, Berkeley, introduced the concept in a famous 1948 paper “Cognitive Maps of Rats and Men.” Three decades later, the neuroscientist John O’Keefe tried to put an electrode in the amygdala of a rat but inserted it instead into the hippocampus, the bilateral brain region deep in the temporal lobe, critical to memory formation. O’Keefe’s instrument began recording the firing pattern of a single cell that strangely seemed to correspond to the rat’s physical location in space. For O’Keefe, these “place” cells were evidence that the hippocampus was the site of Tolman’s cognitive map.

But the cognitive map has also been called the theory that refuses to die. The idea that there is an innate geometric representation of the environment in our brains has dissenters in brain science, anthropology, and psychology. As the neuroscientist Richard Morris points out in The Hippocampus Book, maps are things that people look at to extract information. “Adopting this term for the neural activity of a region of the brain seems to carry with it the mental baggage that there must be some cryptic homunculus that is ‘looking at’ the map to do likewise,” he wrote.2 There is no mechanistic explanation of how humans extract information from this map but because the map is such an easily understood concept, it lives on as a “beguiling metaphor.”

The Fog of the Pandemic Is Returning

The first major change to beset the testing system is entirely because of Trump. Two weeks ago, the CDC changed its official guidance about when Americans should get a coronavirus test. The agency had once maintained that everyone who was exposed to the virus should get tested for it. Now it altered this advice: If someone was exposed to the virus but did not yet have symptoms of COVID-19, they did not necessarily need a test, the guidance said.

New Climate Maps Show a Transformed United States

Taken together, some parts of the U.S. will see a number of issues stack on top of one another — heat and humidity may make it harder to work outside, while the ocean continues to claim more coastal land. The table below ranks the most at-risk counties in the U.S. if all of the perils were combined. You can also sort by individual climate risk to see how each one stacks up, with higher numbers being worse in all categories. The projections are for 2040-2060 under RCP 8.5.

A Biden victory cannot bring normal back

The liberal centre raises hell about the falsehoods of Trump and Johnson, which are undeniably flagrant. However, the brazen fabrications of yesterday – most obviously, those that led to the catastrophe in Iraq, for which there has never been a proper reckoning – did much to pave the way for those of today. And yet only last month, Colin Powell, who personally presented the fallacious case for the invasion of Iraq to the United Nations, was paraded as a star turn at the Democratic National Convention.

Likewise, when Tony Blair recently popped up to warn Johnson against flouting international law by breaching certain aspects of the Brexit withdrawal agreement, the lack of self-awareness on display was breathtaking. It’s not that Blair’s point was wrong, but the fact that he was the one making it allowed the Tories to issue the obvious riposte that their transgression of international law would pale in comparison to his.

Even if the liberal centre were in a stronger position to highlight the cynicism and dishonesty of Trump and Johnson, that wouldn’t be enough without changing the political conditions that gave rise to them. After all, neither Trump nor Johnson came out of nowhere. Trump inherited an apparatus of invasive state surveillance and militarised borders from a predecessor who himself presided over mass deportations, while in Britain, it was New Labour that first indulged bogus moral panics about asylum seekers and laid the foundations for today’s hostile environment.

Both Biden and Starmer might win elections simply by appearing to offer their respective electorates a steady hand. But mounting, interrelated crises stare us in the face: environmental, economic, social and political. Addressing any of them would require, for starters, radically curbing the prerogatives of capitalist vested interests wedded to a destructive status quo. It’s not enough just to install more competent and polite managers, and otherwise leave the same arrangements in place.

Evolutionary Anthropology in the Time of COVID-19

It is imperative that we see this pandemic as a biosocial event. Though SARS-COV2 is a biological entity that has specific biological, deleterious, pathological impacts on the human respiratory system (among others), the biological information is meaningless without the social, historical, political, and economic context. Fuentes gives the example of hand washing. If you understand the structure of the coronavirus, you would see how just some soap and water lifts the outer layers and can save billions of people. But that knowledge of biology is completely useless when there is no access to running water like in a refugee camp or a homeless encampment, or even in some of the Indigenous reservations here in the United States.

A Whistleblower Says Facebook Ignored Global Political Manipulation

The 6,600-word memo, written by former Facebook data scientist Sophie Zhang, is filled with concrete examples of heads of government and political parties in Azerbaijan and Honduras using fake accounts or misrepresenting themselves to sway public opinion. In countries including India, Ukraine, Spain, Brazil, Bolivia, and Ecuador, she found evidence of coordinated campaigns of varying sizes to boost or hinder political candidates or outcomes, though she did not always conclude who was behind them.

“In the three years I’ve spent at Facebook, I’ve found multiple blatant attempts by foreign national governments to abuse our platform on vast scales to mislead their own citizenry, and caused international news on multiple occasions,” wrote Zhang, who declined to talk to BuzzFeed News. Her LinkedIn profile said she “worked as the data scientist for the Facebook Site Integrity fake engagement team” and dealt with “bots influencing elections and the like.”

Wednesday Round Up #15

America Is Trapped in a Pandemic Spiral

Army ants will sometimes walk in circles until they die. The workers navigate by smelling the pheromone trails of workers in front of them, while laying down pheromones for others to follow. If these trails accidentally loop back on themselves, the ants are trapped. They become a thick, swirling vortex of bodies that resembles a hurricane as viewed from space. They march endlessly until they’re felled by exhaustion or dehydration. The ants can sense no picture bigger than what’s immediately ahead. They have no coordinating force to guide them to safety. They are imprisoned by a wall of their own instincts. This phenomenon is called the death spiral. I can think of no better metaphor for the United States of America’s response to the COVID-19 pandemic.

The U.S. enters the ninth month of the pandemic with more than 6.3 million confirmed cases and more than 189,000 confirmed deaths. The toll has been enormous because the country presented the SARS-CoV-2 coronavirus with a smorgasbord of vulnerabilities to exploit. But the toll continues to be enormous—every day, the case count rises by around 40,000 and the death toll by around 800—because the country has consistently thought about the pandemic in the same unproductive ways.

When the World Isn’t Designed for Our Bodies

If we’re overly besotted with objects that promise assistance, maybe that’s because our default objects—the givens of the built world—can seem so incompatible with our needs. Look down. Your chair, Hendren declares, is murdering you. (The historian Galen Cranz has noted correlations between chair use and “back pain of all sorts, fatigue, varicose veins, stress, and problems with the diaphragm, circulation, digestion, and general body development.”) Yet long stretches of sitting are a societal norm. Why? Hendren invokes the chair’s historical function: in many cultures, including corporate culture, throne-like seats symbolize power and status. We may also be drawn to chairs’ animal charisma, to their torsos, bottoms, and four sturdy legs.

Regardless, Hendren argues, we could be sitting so much more comfortably if furniture makers were to attend as closely to matters of substance and sustainability as they do to matters of style. Disability activists, of course, have been making such arguments for years. One corollary of universal design—the idea that my perfect chair equals your perfect chair—states that improvements undertaken with disabled bodies in mind are likely to benefit everyone. (The telephone, for instance, emerged out of Alexander Graham Bell’s work with deaf students.)

Hendren gives universal design a hearing, but she would rather remain alert to difference. The book thus lingers over “diffuse design,” which thrives on grassroots connections. In the diffuse model, artists, guided by local desires, make bespoke modifications to a received archetype.

Think 2020′s disasters are wild? Experts see worse in future

“A year like 2020 could have been the subject of a marvelous science fiction film in 2000,” Cobb said. “Now we have to watch and digest real-time disaster after disaster after disaster, on top of a pandemic. The outlook could not be any more grim. It’s just a horrifying prospect.”

“The 2030s are going to be noticeably worse than the 2020s,” she said.

University of Michigan environment dean Jonathan Overpeck, a climate scientist, said that in 30 years because of the climate change already baked into the atmosphere “we’re pretty much guaranteed that we’ll have double what we have now.”

Expect stronger winds, more drought, more heavy downpours and floods, Abdalati said.

At 31, I have just weeks to live. Here’s what I want to pass on

I imagined settling down in my 30s or 40s with kids, a mortgage and so on. Or maybe I wouldn’t. Maybe my friends’ children would call me Uncle Elliot as their parents gathered in the kitchen looking slightly concerned about their single 45-year-old friend about to set off travelling around Mongolia. Either way, growing older with my mates and living my life to the full was always my ambition.

Of course, the second part of this storyline won’t be written now. It’s a shame I don’t get to see what happens. But everybody dies, and there will always be places and experiences missing from anyone’s life – the world has too much beauty and adventure for one person to see. I will miss marriage or children, blossoming careers and lives moving on. But I’m not alone in my life being cut short, and I think my time has been pretty good.

Is America in the Early Stages of Armed Insurgency?

Meanwhile, a powder keg is building. FBI background checks for gun sales hit 3.9 million in June—an all-time high. Many of them were for first-time gun buyers—by definition untrained, possibly rash in their actions. An estimated 20 million Americans carry a gun when they leave their homes. It takes just a few trigger-pullers to set off a conflagration; even in intense insurrections, such as the postwar rebellion in Iraq, only 2 percent of insurgents actually fired their weapons.

Kilcullen sees a pattern similar to the patterns that precipitated insurgencies in Colombia, Libya, and Iraq. The key factor is the rise of fear. He cites Stathis Kalyvas’ book The Logic of Violence in Civil War as observing that fear, not hate, drives the worst atrocities. “Every civil war and insurgency of the last 50 years has been driven by fear,” Kilcullen told me. Today’s politics and social tensions are dominated by three fears: fear of other social groups, fear that those other groups are encroaching on one’s territory, and fear that the state no longer has the ability to protect the people.

Things do not have to get worse. “Incipient insurgency” doesn’t mean “inevitable insurgency.” We are still in the very early phase of this rampage—a “pre-McVeigh moment,” as Kilcullen puts it. And the extent of disorder has been exaggerated, usually for political motives. When violence has occurred during protests, it has been confined to just a few blocks; it hasn’t spread throughout a city. Contrary to Trump and other Republican politicians, New York is not a “hellscape,” Portland is not “ablaze all the time,” and Chicago is not more dangerous than Afghanistan.

How to Deal With the Anxiety of Uncertainty

“Waiting periods are marked by two existentially challenging states: We don’t know what’s coming, and we can’t do much about it,” Sweeny explains. “Together, those states are a recipe for anxiety and worry. People would often rather deal with the certainty of bad news than the anxiety of remaining in limbo.”

That’s what researchers at three institutions in the UK found in a 2013 experiment, when they attached electrodes to 35 subjects and asked them to choose between receiving a sharp shock immediately or waiting for a milder one. The vast majority chose the more painful option, just to get it out of the way. “It’s counterintuitive,” admits Giles Story, one of the academics behind the study. “But it’s a testament to how anxiety-inducing and miserable it can be to have things looming in the future.”

How Scientists Discovered the Staggering Complexity of Human Evolution

From the rich assortment of fossils and artifacts recovered from around the world in the past century, however, paleoanthropologists can now reconstruct something of the timing and pattern of human evolution. The finds clearly show that this single-file scheme is no longer tenable. Evolution does not march steadily toward predetermined goals. And many hominin specimens belong not in our direct line of ancestry but on side branches of humankind—evolutionary experiments that ended in extinction.

From the outset, our defining traits evolved not in lockstep but piecemeal. Take our mode of locomotion, for example. H. sapiens is what anthropologists call an obligate biped—our bodies are built for walking on two legs on the ground. We can climb trees if we need to, but we have lost the physical adaptations that other primates have to arboreal life. Fragmentary fossils of the oldest known hominins—Sahelanthropus tchadensis from Chad, Orrorin tugenensis from Kenya and Ardipithecus kadabba from Ethiopia—show that our earliest ancestors emerged by around seven million to 5.5 million years ago. Although they are apelike in many respects. all of them exhibit characteristics associated with walking on two legs instead of four. In Sahelanthropus, for example, the hole in the base of the skull through which the spinal cord passes has a forward position suggestive of an upright posture. A bipedal gait may thus have been one of the very first traits that distinguished hominins from ancestral apes.

Excellent thread on advances in research on human evolution from a premier science writer – she highlights all the pieces she has written that provide an excellent recounting of the explosion in research over the past 20 years.

In the Animal Kingdom, the Astonishing Power of the Number Instinct

If these bacteria are in dilute water solutions (where they are alone), they make no light. But when they grow to a certain cell number of bacteria, all of them produce light simultaneously. Therefore, Vibrio fischeri can distinguish when they are alone and when they are together.

Somehow they have to communicate cell number, and it turns out they do this using a chemical language. They secrete communication molecules, and the concentration of these molecules in the water increases in proportion to the cell number. And when this molecule hits a certain amount, called a quorum, it tells the other bacteria how many neighbors there are, and all bacteria glow. This behavior is called “quorum sensing”: The bacteria vote with signaling molecules, the vote gets counted, and if a certain threshold (the quorum) is reached, every bacterium responds.