Flocking together

One of the most mesmerizing sights in nature is the collective motion of large groups of animals.

I remember watching films by Jacques Cousteau as a kid, and being fascinated by his underwater footage of schools of fish swimming along and then turning as one, the light flickering from their silvery sides as if they were each reflective scales on a giant single organism.  Murmurations of starlings barely even look real; the flocks swirl and flow like some kind of weird, airborne fluid.  But the most astonishing example of collective motion I've ever seen was when Carol and I visited Bosque del Apache Wildlife Refuge, in central New Mexico, a few years ago, during the migration of snow geese through the region.

"Get there early," we were told.  "At least a half-hour before sunrise.  You'll be glad you did."

We arrived just as the light was growing in the eastern sky.  The wetland was full of tens of thousands of snow geese, all moving around in a relaxed sort of fashion, calling softly to each other.  The brightness in the sky grew, and then -- without any warning at all...

... BOOM.

They all exploded into the air, seemingly simultaneously.  We have wondered many times since what the signal was; there was nothing we could discern, no handful of birds that launched first, no change in the vocalizations that a human would interpret as, "Now!"  One moment everything was calm; the next, the air was a hurricane of flapping wings.  They whirled around, circling higher and higher, and within ten minutes they were all gone, coursing through the sky toward their next destination.

[Image licensed under the Creative Commons CrunchySkies, Snow goose migration at Squaw Creek National Wildlife Refuge, Feb 2013, 25, CC BY-SA 3.0]

How animals manage such feats, moving as a unit without colliding or leaving members behind -- and seemingly without any central coordination -- has long fascinated zoologists.  Way back in 1987, computer simulation expert Craig Reynolds showed (using software called "Boids") that with only a handful of simple rules -- stay within so many wing-lengths of your nearest neighbors but not close enough to touch, match the speed of your neighbors within ten percent either way, steer toward the average heading of your nearest neighbors, give other members a chance to be in any given position in the group -- he was able to create simulated flocking behavior that looked absolutely convincing.  

Last week, a paper out of the Max Planck Gesellschaft showed there's another factor that's important in modeling collective motion, and this has to do with the fact that flying or swimming animals have a rhythm.  Look, for example, at a single fish swimming in an aquarium; its motion forward isn't like a car moving at a steady speed down a highway, but an oscillating swim-glide-swim-glide, giving it a pattern a little like a Slinky moving down a staircase.

Biologist Guy Amichay, who led the research, found that this gives schools of fish a pulse; he compares it to the way we alternate moving our legs while walking.  "Fish are coordinating the timing of their movements with that of their neighbor, and vice versa," Amichay said.  "This two-way rhythmic coupling is an important, but overlooked, force that binds animals in motion.  There's more rhythm to animal movement than you might expect.  In the real world most fish don't swim at fixed speeds, they oscillate."

The key in simulating this behavior is that unlike the factors that Reynolds identified, getting the oscillating movement right depends on neighboring fish doing the opposite of what their nearest neighbors are doing.  The swim-glide pattern in one fish triggers a glide-swim pattern in its friends; put another way, each swim pulse creates a delay in the swim pulse of the school members around it.  

"It's fascinating to see that reciprocity is driving this turn-taking behavior in swimming fish, because it's not always the case in biological oscillators," said study co-author Máté Nagy.  "Fireflies, for example, will synchronize even in one-way interactions.  But for humans, reciprocity comes into play in almost anything we do in pairs, be it dance, or sport, or conversation,"

"We used to think that in a busy group, a fish could be influenced by any other member that it can see," said co-author Iain Couzin. "Now, we see that the most salient bonds could be between partners that choose to rhythmically synchronize."

So zoologists have taken another step toward comprehending one of the most fascinating phenomena in nature; the ability of animals to move together.  Something to think about next time you see a school of fish or a flock of birds in flight.  Getting it right requires rapid and sophisticated coordination we are only now beginning to understand.

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Birds of a feather

I should probably avoid social media altogether, given what a cesspit of ugliness it can be sometimes.

Unfortunately, it's provided the simplest way of keeping in touch with dear friends I seldom see, especially during the height of the pandemic (when I kind of wasn't seeing anyone).  But to say it amplifies the echo chamber effect is an understatement.  Not only do we tend to link on social media to like-minded folks (can't tell you how many times I've heard someone say that they'd unfriended someone solely because of some opinion or another, usually political), but with the few non-like-minded social media friends we have and keep, it takes so much energy to argue that most of us just sigh heavily, shrug our shoulders, and move on, even when confronted with opinions completely antithetical to our own.

Take, for example, what I saw posted yesterday -- a meme saying, "All I'm saying is, if my dog got three rabies shots and then still got rabies, I'd begin to get suspicious."  (It took all my willpower not to respond, "Oh, how I wish that was all you were saying.")  In any case, not only does the post trumpet zero understanding about how vaccinations and immunity work, it's back to the maddening phenomenon of a layperson thinking an opinion formed from watching Fox News and doing a ten-minute read of some guy's website constitutes "research."

If that wasn't bad enough, a friend-of-the-friend -- no one I know -- responded, "It's what comes from drinking the libtard kool-aid."  So, let's take the ignorant post and make it worse by slathering on some ugly vitriol demeaning half the residents of the country.

And what did I do in response?

Nothing.

I just didn't have the energy to get drawn in.  Plus, there's a sense of such argument being futile anyhow.  I seriously doubt anyone, in the history of the internet, has ever had their opinion changed by arguing a point online with a total stranger.

Only a few minutes after seeing the post, though, I stumbled on some research out of the University of Buffalo that contains at least a glimmer of hope; that the screeching you hear on social media isn't necessarily reflective of the attitudes that the majority of people have, because these platforms amplify the loudest voices -- not necessarily the ones that make the best sense, or are even the most common.

In a paper in The Journal of Computer-Mediated Communication, Yini Zhang, Fan Chen, and Karl Rohe looked at our tendency to form "flocks" on social media.  By studying the posts from 193,000 Twitter accounts, and the 1.3 million accounts those accounts follow, they were able to uncover patterns of tweets and retweets, and found the strongest-worded opinions were the ones that got liked and retweeted the most.  They called this phenomenon murmuration -- the term comes from the flocking behavior of starlings -- capturing the idea that online expression of opinions forms and shifts not based on actual changes in the information available, but on who is saying what, and how stridently.

"By identifying different flocks and examining the intensity, temporal pattern and content of their expression, we can gain deeper insights far beyond where liberals and conservatives stand on a certain issue," said study lead author Yini Zhang, in an interview in Science Daily.  "These flocks are segments of the population, defined not by demographic variables of questionable salience, like white women aged 18-29, but by their online connections and response to events.  As such, we can observe opinion variations within an ideological camp and opinions of people that might not be typically assumed to have an opinion on certain issues.  We see the flocks as naturally occurring, responding to things as they happen, in ways that take a conversational element into consideration."

The fact that the social media flocking doesn't mirror the range of opinion out there is heartening, to say the least.  "[S]ocial media public opinion is twice removed from the general public opinion measured by surveys," Zhang said.  "First, not everyone uses social media.  Second, among those who do, only a subset of them actually express opinions on social media.  They tend to be strongly opinionated and thus more willing to express their views publicly."

It's not just political discourse that can be volatile.  A friend of mine just got blasted on Facebook a couple of days ago, out of the blue, because she posts stuff intended to be inspirational or uplifting, and one of her Facebook friends accused her of being "self-righteous," and went on to lambaste her for her alleged holier-than-thou attitude.  The individual in question doesn't have a self-righteous bone in her whole body -- she might be the only person I know who has more of a tendency to anxious self-doubt than I do -- so it was a ridiculous accusation.  But it does exemplify the sad fact that a lot of us feel freer to be unkind to people online than we ever would face-to-face.  

The important point here is that it's easy to see the nastiness and foolishness on social media and conclude that this is the way the majority of the public believes and acts, but the Zhang et al. study suggests that the majority of the opinions of this sort are generated by a few strident people.  Only afterward do those posts act like a magnet to the like-minded followers they already had.

So as hard as it is to keep in mind sometimes, I maintain that the majority of people are actually quite nice, and want the same things we want -- safety, security, the basic necessities, health and happiness for our friends and family.  The ugly invective from people like the guy who made the "libtard" comment is far from a majority opinion, and shouldn't feed into a despairing sense that everyone is horrible.

The flocks, apparently, aren't led by the smartest birds, just the ones who squawk the loudest.  A lot of the rest are tagging along for the ride.  There's a broader population at the center, opinion-wise, than you'd think, judging by what you see on social media.  And when the birds step away from social media, most of them turn out to be ordinary tweeters just trying to stay with the flock-mates they feel the most comfortable with.

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The sound of a friendly voice

Given my inability to recognize faces, I've developed a number of compensatory mechanisms.  One is that I remember people by memorizing specific features; he's the guy with curly black hair, she's the woman with small oval glasses and a tattoo on her right hand.  I notice how people walk and how they carry their posture; I can sometimes recognize people I know well even if they're walking away from me, if they have a distinctive gait (which many people do, whether they realize it or not).

But for me the most important thing is the sound of their voices.  I think that may be why it took me so long to figure out I'm face blind; often, all people have to do is say a few words and I immediately know who they are, so the fact that their faces don't trigger the immediate recognition most people have doesn't hamper me as much.

It turns out that I'm not alone in relying on vocalizations for identifying who's around.  According to a paper last week in Science Advances, zebra finches have an ability to recognize their flock mates' unique vocalizations that rivals that of most humans.

[Image licensed under the Creative Commons JJ Harrison (https://www.jjharrison.com.au/), Taeniopygia guttata - Bushell's Lagoon, CC BY-SA 4.0]

In "High-Capacity Auditory Memory for Vocal Communication in a Social Songbird," a team composed of biologists Kevin Yu, William Wood, and Frederic Theunissen, all of the University of California-Berkeley, used rewards to train a bunch of Australian zebra finches (Taeniopygia guttata) and see how far they could push the birds' ability to distinguish between the vocalizations of different members of their species.  And surprisingly -- at least to anyone who has heard the twittering cacophony of a cageful of zebra finches -- these birds could distinguish between the voices of forty or more of their friends.

The authors write:

Effective vocal communication often requires the listener to recognize the identity of a vocalizer, and this recognition is dependent on the listener’s ability to form auditory memories.  We tested the memory capacity of a social songbird, the zebra finch, for vocalizer identities using conditioning experiments and found that male and female zebra finches can remember a large number of vocalizers (mean, 42) based solely on the individual signatures found in their songs and distance calls.  These memories were formed within a few trials, were generalized to previously unheard renditions, and were maintained for up to a month.  A fast and high-capacity auditory memory for vocalizer identity has not been demonstrated previously in any nonhuman animals and is an important component of vocal communication in social species.

This is the first time this kind of individual vocal recognition has been demonstrated in a non-human animal.  "For animals, the ability to recognize the source and meaning of a cohort member's call requires complex mapping skills, and this is something zebra finches have clearly mastered," study co-author Theunissen said, in an interview with Science Direct.  "They have what we call a 'fusion fission' society, where they split up and then come back together.  They don't want to separate from the flock, and so, if one of them gets lost, they might call out 'Hey, Ted, we're right here.'  Or, if one of them is sitting in a nest while the other is foraging, one might call out to ask if it's safe to return to the nest...   I am really impressed by the spectacular memory abilities that zebra finches possess in order to interpret communication calls.  Previous research shows that songbirds are capable of using simple syntax to generate complex meanings and that, in many bird species, a song is learned by imitation.  It is now clear that the songbird brain is wired for vocal communication."

Social behavior is fascinating, and requires an astonishing repertoire of subtle perceptual skills to work well.  Take, for example, flocking behavior in starlings.  If you live in the United States, Canada, or western Europe, you've probably seen the flocks of black birds that swirl and move, almost in unison, as if the entire flock shared a single mind.  Scientists still don't know exactly how they manage it, but experiments have demonstrated that each bird monitors its seven nearest neighbors on either side, and determines its own flight path from those neighbors' movements.  We see that kind of thing in human crowds and in herds of cattle, of course; but the speed and degree of sophistication shown by starlings is mind-boggling.  The passage of information from one bird to the next is lightning-fast and shows almost no signal degradation (the kind of thing that happens in the game of Telephone) across the entire flock.  The result: they can move very nearly as one.  Take a look at this incredible video of a starling flock in motion:

So we aren't the only ones with fancy communication abilities.  Everywhere we look in the natural world, we see the amazing ways in which the species we share the Earth with survive, interact, and reproduce.  It can seem like a harsh, bleak world at times -- but if you want to be reminded of the astonishing beauty and wonder this planet contains, all you have to do is look around you.

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I'm fascinated with history, and being that I also write speculative fiction, a lot of times I ponder the question of how things would be different if you changed one historical event.  The topic has been visited over and over by authors for a very long time; three early examples are Ray Bradbury's "The Sound of Thunder" (1952), Keith Roberts's Pavane (1968), and R. A. Lafferty's screamingly funny "Thus We Frustrate Charlemagne" (1967).

There are a few pivotal moments that truly merit the overused nametag of "turning points in history," where a change almost certainly would have resulted in a very, very different future.  One of these is the Battle of the Teutoburg Forest, which happened in 9 C.E., when a group of Germanic guerrilla fighters maneuvered the highly-trained, much better-armed Seventeenth, Eighteenth, and Nineteenth Roman Legions into a trap and slaughtered them, almost to the last man.  There were twenty thousand casualties on the Roman side -- amounting to half their total military forces at the time -- and only about five hundred on the Germans'.

The loss stopped Rome in its tracks, and they never again made any serious attempts to conquer lands east of the Rhine.  There's some evidence that the defeat was so profoundly demoralizing to the Emperor Augustus that it contributed to his mental decline and death five years later.  This battle -- the site of which was recently discovered and excavated by archaeologists -- is the subject of the fantastic book The Battle That Stopped Rome by Peter Wells, which looks at the evidence collected at the location, near the village of Kalkriese, as well as the historical documents describing the massacre.  This is not just a book for history buffs, though; it gives a vivid look at what life was like at the time, and paints a fascinating if grisly picture of one of the most striking David-vs.-Goliath battles ever fought.

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