Why does nature create patterns? A physicist explains the molecular-level processes behind crystals, stripes and basalt columns

Curious Kids is a series for children of all ages. If you have a question you’d like an expert to answer, send it to curiouskidsus@theconversation.com.

Why does nature always create a pattern? – Saloni G., age 16, Alwar, Rajasthan, India

The reason patterns often appear in nature is simple: The same basic physical or chemical processes occur in many patterned substances and organisms as they form. Whether in plants and animals or rocks, foams and ice crystals, the intricate patterns that happen in nature come down to what’s happening at the level of atoms and molecules.

A pattern in nature is any regularly repeated arrangement of shapes or colors. Some of the most striking examples include the hexagonal arrays of rocks at Giant’s Causeway in the United Kingdom, the beautiful fractal arrangements of florets on a Romanesco broccoli and the colorful stripes and spots on tropical fish.

Patterns like these begin to form at a small scale when materials undergo processes like drying, freezing, wrinkling, diffusing and reacting. Those changes then give rise to complex patterns at a larger scale that people can see.

Patterns in ice and rock

Imagine delicate frozen crystals on a windowpane during a cold day. What creates that pattern?

When water freezes, its molecules begin clustering together. Water molecules have a particular bent shape that causes them to stack into clusters shaped like hexagons as they freeze.

As the cluster grows, many outside factors, including humidity and temperature, begin to affect its overall shape. If the water is freezing on a windowpane, for example, small and random imperfections on the glass surface redirect the stacking and create the larger pattern.

This same process of stacking molecules is responsible for the striking variety of snowflake shapes.

What about the amazing patterns of the basalt columns at Giant’s Causeway? These formed 50 million to 60 million years ago, as lava – hot rocky fluid from deep underground – rose to the Earth’s surface and began to lose heat. The cooling caused the top layer of basalt to contract. The deeper, hot layers resisted this pulling, creating cracks in the top layer.

As the lava cooled, the cracks spread deeper and deeper into the rock. The particular molecular qualities of basalt, as well as the basic physics of how materials fracture apart – laws of physics universal to all substances on Earth – caused the cracks to meet up with one another at certain angles to create hexagons, much like the stacking water molecules.

Eventually, the cooling basalt broke into the hexagon-shaped columns of rock that still create such an impressive pattern millions of years later.

Patterns in animals

The creation of complex patterns in living organisms also begins with simple mechanisms at the molecular level. One important pattern-making process involves the way diffusing chemicals react with one another.

Imagine how a drop of food coloring spreads in a glass of water – that’s diffusion.

In 1952, English mathematician Alan Turing showed that a chemical spreading like this within another chemical can lead to the formation of all kinds of patterns in nature.

Scientists have proved that this process reproduces the patterns of a leopard’s spots, a zebra’s stripes and many other animal markings.

What makes these markings consistent from generation to generation? As animal species evolved, these chemical reactions evolved with them and became part of their genetic codes. This might be because the markings helped them survive. For example, a tiger’s stripes camouflage it while hunting in a forest or grassland, making it easier to surprise and catch its prey.

However, researchers are still working out the details of which particular chemicals are involved.

Scientists do not always know the purpose of a pattern, or even if there is one. The molecular processes involved are simple enough that they might coincidentally generate a pattern.

For example, in my research team’s work studying plant pollen grains, we have seen a huge variety of patterns, including spikes, stripes and many more.

We don’t yet understand why a plant produces one particular pollen pattern rather than another. Whatever the ultimate use this and other patterns in nature may have, their variety, complexity and order are amazing.

Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to CuriousKidsUS@theconversation.com. Please tell us your name, age and the city where you live.

And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.

Maxim Lavrentovich, Assistant Professor of Theoretical Biophysics, University of Tennessee

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Explainer: Socrates and the life worth living

Socrates was notoriously annoying. He was likened to a gadfly buzzing around while one is trying to sleep. The Oracle of Delphi declared him the wisest of all human beings. His life and death would go on to shape the history of Western thought.

And yet he proclaimed to know nothing. The genius of Socrates lay in his professed ignorance of what it means to be human.

Socrates (469-399 BCE) grew up in Athens over two and half thousand years ago. At the time, the Athenians were recovering from a devastating war with the Persians. As they rebuilt, the military general and politician, Pericles, championed democracy as the form of government to bring Greece into its Golden Age.

The Athenians practised a direct (as opposed to representative) form of democracy. Any male over the age of 20 was obligated to take part. The officials of the assembly were randomly selected through a lottery process and could make executive pronouncements, such as deciding to go to war or banishing Athenian citizens.

The Athens of Pericles flourished. Bustling crowds of traders from around the Mediterranean gathered at the port of Piraeus. In the Athenian agoras – the central marketplaces and assembly areas – the active social and political lives of the Athenian citizens would inspire the mind of Socrates.

Socrates at war

Alcibiades, who would go on to become a prominent Athenian statesman and general, recounts a story of what might be a pivotal moment in the development of Socrates’ thinking.

One morning during the campaign of Potidaea, Socrates became transfixed by a problem that he could not seem to solve. An entire day passed and Socrates had still not moved. In awe, and probably curious to see how long he could keep it up, his fellow soldiers moved their beds outside to watch him during the night. It was not until dawn the next morning that Socrates said a prayer to the new day and walked away.

Jonathan Lear argues in his Tanner Lectures that Socrates is not just standing still because he is lost in thought; he is standing still because he cannot walk. He is standing “not knowing what his next step should be”. Socrates wants to move in the right direction, but does not know what direction that is.

We will never know what Socrates was thinking about. But after standing still and thinking, he appears to have become invigorated. Alcibiades tells us that in the battle that followed Socrates saved his life. For the remainder of the campaign, Socrates fought with a fierceness and bravery that exemplified true courage.

Socrates the gadfly

Socrates never wrote anything down. He hungered for the lively exchange of ideas and believed that writing only served to imprison a thought in letters. He argued that the written word shared a strange quality with paintings. Both appear to us “like living beings, but if one asks them a question, they preserve a solemn silence”.

Much of what we know of Socrates’ activities and conversations, and his death, was recorded by his devoted student Plato. Scholarly debate continues about just how much of Plato’s written record of Socrates’ interrogations we can attribute to Socrates himself. At some point in the Platonic corpus, Socrates becomes a mouthpiece for Plato’s own ideas, but no one can agree precisely when.

Socrates was unsure of what to make of being called the wisest of all human beings. He dedicated his time to questioning fellow Athenians about the nature of things, interrogating ideas such as friendship, love, justice and piety. He was searching for what he believed to be the highest good: knowledge.

The gadfly could show up anywhere. In Plato’s Euthyphro, for example, Socrates bumps into Euthyphro, who is on his way to court about to prosecute his father:

What strange thing has happened, Socrates, that you have left your accustomed haunts in the Lyceum and are now haunting the portico where the king archon sits?

Socrates is intrigued by Euthyphro’s legal case, and so begins his inquiry:

do you think your knowledge about divine laws and holiness […] is so exact that […] you are not afraid of doing something unholy yourself in prosecuting your father for murder?

Almost every Socratic dialogue is centred around Socrates’ recognition of his own ignorance. In Euthyphro, the subject he interrogates is piety. What follows adheres to a structure shared by most of the other dialogues, which is known as elenchus or the Socratic method.

Its basic form is as follows:

1. Socrates engages an interlocutor who appears to possess knowledge about an idea

2. the interlocutor makes an attempt to define the idea in question

3. Socrates asks a series of questions which test and unravel the interlocutor’s definition

4. the interlocutor tries to reassemble their definition, but Socrates repeats step three

5. both parties arrive at a state of perplexity, or aporia, in which neither can any further define the idea in question.

We can gain a sense of the frustration that this caused some of Socrates’ unwilling victims. Take the final lines of his encounter with Euthyphro as an example:

Socrates: Then don’t you see that now you say that what is precious to the gods is holy? And is not this what is dear to the gods?

Euthyphro: Certainly.

Socrates: Then either our agreement a while ago was wrong, or if that was right, we are wrong now.

Euthyphro: So it seems.

Socrates: Then we must begin again at the beginning and ask what holiness is. Since I shall not willingly give up until I learn. […]

Euthyphro: Some other time, Socrates. Now I am in a hurry and it is time for me to go.

In Meno, another of Plato’s dialogues, Socrates likens the sting of aporia to that of an electric stingray:

I find you are merely bewitching me with your spells and incantations, which have reduced me to utter perplexity. And if I am indeed to have my jest, I consider that both in your appearance and in other respects you are extremely like the flat torpedo sea-fish; for it benumbs anyone who approaches and touches it, and something of the sort is what I find you have done to me now. For in truth I feel my soul and my tongue quite benumbed, and I am at a loss what answer to give you.

Throughout the dialogues, Socrates demonstrates the disruptive and disorientating experience of aporia, which emerges from philosophical activity. Reflecting upon the declaration of the Oracle of Delphi, we learn that Socrates was wise because, unlike his interlocutors, he did not proclaim to know what he was ignorant of.

Corrupting the youth and replacing the gods

In the early days of democracy and in a society which was rapidly expanding, one would think that a revolutionary thinker like Socrates would be a highly prized instrument of intellectual progress. But not everyone appreciated the disorientating sting of the gadfly’s thinking.

Plato would later comment on how the Athenians – and perhaps societies in general – react when faced with the disruptive force of critical reflection.

His famous allegory of the cave, which forms part of his Republic, is in many ways the story of a philosopher – the story of his great teacher, Socrates.

The allegory begins with prisoners locked in a cave. All the prisoners can see are the shadows of the passing guards reflected on the wall, and the echoes of the world behind them. This is the condition of a society content with the mere illusions of knowledge, a society that is unreflective and stagnant.

One prisoner manages to escape. Turned towards the entry of the cave, he first notices the brightness of the light – like knowledge, the light is uncomfortable and disruptive after years of contentment with shadows.

Escaping the cave, the prisoner

can see the reflections of people and things in water and then later see the people and things themselves. Eventually, he is able to look at the stars and moon at night until finally he can look upon the sun itself.

Only after he is able to look straight at the “sun itself” – i.e. knowledge of what is good – “is he able to reason about it” and what it is. The freed prisoner, argues Plato, would realise that life outside is far superior to being inside the cave. He would return and encourage the prisoners to free themselves and look around. But the comfort of their belief in the world of shadows and echoes is a strong force to overcome.

Plato says that the prisoners, fearing what awaits outside of the cave, would react violently towards the freed prisoner – even killing him in order to keep the peace.

This was Socrates’ fate.

When the citizens of Athens had finally had enough of Socrates’ pestering questions, they banded together and accused him of corrupting the youth and attempting to replace the old gods.

He was imprisoned. His followers planned an escape, but he refused. Socrates questioned what was to be gained by escaping. Life itself is not ultimately valuable – surely, he says, it is a good and just life that we ultimately value. If he were to escape, he would only be tarnishing his good life with an act of vengeance against the misinformed Athenian citizens. He had nothing to gain by escaping. He could only preserve the harmony of his own soul by accepting his fate.

In his final stand in front of the Athenian judges, Socrates denies all charges. His only crime was forcing Athenians to think:

If again I say that to talk every day about virtue and the other things about which you hear me talking and examining myself and others is the greatest good to man, and that the unexamined life is not worth living, you will believe me still less.

If you are to put me to death, warns Socrates, you will not easily find another like me. Striking dead the gadfly of Athens is easy, but “then you would sleep on for the remainder of your lives, unless the god in his care of you gives you another gadfly”.

But the judges had made up their minds. The majority voted that Socrates would be executed by drinking hemlock.

Socrates teaches us that philosophical contemplation prepares us for the good life. The experience of aporia – in all of its discomfort and disruption – is the very catalyst of wonder. The philosopher, the lover of wisdom, is anyone who dares to escape the cave and look upon the sun, anyone who lives for the values Socrates died for.

Oscar Davis, Lecturer in Philosophy and History, Bond University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

For the first time, robots on Mars found meteorite impact craters by sensing seismic shock waves

Since 2018, NASA’s InSight mission to Mars has recorded seismic waves from more than 1,300 marsquakes in its quest to probe the internal structure of the red planet. The solar panels of the car-sized robotic lander have become caked with Martian dust, and NASA scientists expect it will completely power down by the end of 2022.

But the internal rumblings of our planetary neighbour aren’t the only things that InSight’s seismometers detect: they also pick up the thuds of space rocks crashing into the Martian soil.

In new research published in Nature Geoscience, we used data from InSight to detect and locate four high-speed meteoroid collisions, and then tracked down the resulting craters in satellite images from NASA’s Mars Reconnaissance Orbiter.

Rocks from space

The Solar System is full of relatively small rocks called meteoroids, and it’s common for them to collide with planets. When a meteoroid encounters a planet with an atmosphere, it heats up due to friction – and may burn up entirely before reaching the ground.

On Earth, we know these incoming meteoroids as shooting stars, or meteors: beautiful events to observe in the night sky. Sometimes a meteoroid explodes when it reaches the thicker atmosphere closer to the ground, creating a spectacular airburst.

Occasionally, a space rock survives its fiery path through the air and drops to the ground, where it is known as a meteorite.

A few of these meteorites hit the surface at such speed they blast a hole in the ground called an impact crater. Compared to a human lifetime, these events are very rare on Earth.

Recording space rock impacts

Scientists have detected the vibrations from meteoroid airbursts using seismic detectors numerous times, including a recent survey of bright meteors above Australia.

However, only once has a high-speed space rock crashing into the ground been observed both visually and with modern seismic equipment. This was an impact crater that formed in 2007 near the village of Carancas in Peru.

Numerous impacts were detected on the Moon by the network of seismic sensors set up during the US Apollo missions of the 1960s and ’70s. However, there was no recording of a natural impact associated with visual detection of a new crater.

The closest things to such an observation were artificial impacts: the crash-landings of the booster rockets of the ascent modules that lifted Apollo astronauts off the Moon.

These human-made impacts on the Moon were recorded both in seismic data and visual imagery from orbit. These data were recently used to test simulations of how impacts produce seismic waves.

Martian meteorites

Incoming meteoroids make waves in the atmosphere and also the ground. The atmosphere of Mars is equivalent to 1% of the Earth’s, and has a different chemical composition. This means meteor events on Mars take a different form.

For meteor events large enough to drop a meteorite, the fate of the meteorite and any resulting crater is different from what we have come to expect on our home planet.

Here on Earth, or on the Moon, single craters are the norm. On Mars, however, about half the time a high-speed space rock will burst in the atmosphere shortly before impact, resulting in a tightly grouped cluster of craters.

The separation of these individual fragments remains close at ground level, forming a cluster of small impacts.

From vibrations to craters

Recently, the InSight mission has observed acoustic and seismic waves from four meteoroid impact events. These waves travel at different speeds, and comparing their different arrival times and other properties allowed us to estimate the location of the impacts.

These impact locations were then confirmed with satellite imaging from the Mars Reconnaissance Orbiter.

Knowing the size and exact location of these impact craters helps us calculate the size and speed of the incoming space rock and how much energy the impact released.

Once we are confident we know something about the impact that created the seismic waves we detected, we can use the waves to learn about the interior of Mars. What’s more, when we compare seismic observations on Mars with observations from Earth and the Moon, we can learn more about how the planets formed and how the Solar System evolved.

Katarina Miljkovic, ARC Future Fellow, School of Earth and Planetary Sciences, Curtin University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

10 months and hundreds of subjects: how I took portrait photography to the streets of Parramatta

For the past ten months, I have photographed hundreds of people in the Western Sydney suburb of Parramatta for a portrait project called Being Together: Parramatta Yearbook.

The portraits in the yearbook show the people who live, work and play in Parramatta against the backdrop of an ever-changing city.

The way a photographer and subject come together to make a portrait is usually invisible in a portrait.

Here, instead of trying to reveal the elusive individuality of a person, I have been focusing on the social dynamics of portraiture – what happens behind the scenes between me and the people I’m photographing.

As Daniel Palmer notes in his book Photography and Collaboration, portraiture is by definition relational and collaborative. That is, the process of photographic portraiture inherently brings the photographer and subjects together to arrive at an image.

In the context of this project, coming together for a portrait creates playful opportunities for social interactions among strangers.

It is amazing what strangers will share with me in the space of five minutes.

Two men reveal they are brothers and haven’t seen each other for ten years.

One woman tells me she thinks she’s ugly and asks me to make her look beautiful.

Another keenly describes the floral wonders she is holding from her community garden.

One man whispers that he can’t speak English.

Another tells me he’s in a hurry to go to lunch.

We chat about the everyday things, the weather, COVID, shopping and Rugby League.

There are stories of time spent in jail, and lives being turned around.

New arrivals to Australia speak of their family in lands faraway and citizens who have lived all their lives in Parramatta share insights on the city.

These are the stories photography can’t capture in the silent stillness of the image, but that’s no reason not to continue.

Performing photography

Setting up a studio in the street and inviting people to pose together in front of the camera is a thing to see. We always had audiences of passersby watching and it wasn’t long before they were also in front of the camera.

If you look closely at the portraits there are talkative details and warm gestures: micro-movements of the body where people touch each other or hold hands; the spaces between our bodies; instances when we are caught by the camera laughing, chatting and applying lipstick.

I also see myself in action. I am both photographer and subject, a stranger dressed in red, wanting desperately to be with people, to steer them through a photographic moment, to pose and be uncomfortable together.

When people have their portraits made I want to know whether they enjoyed it or found it excruciating and awkward. After the photo is taken, we walk up to the laptop tethered to the camera and look at the photographs. They indicate which portraits they like and hate. I listen and take notes.

Involving people in the selection process creates instant trust.

In bringing people together before a camera, I became acutely aware of photography’s potential to foster social inclusion, social participation, visibility and a sense of belonging and connection to one’s place and people.

Photography is something we all do. It is familiar and familial. Group portraits activate a social encounter and conversation, listening and storytelling.

The social experience of photography is also extended through time. After the photographs have been taken and printed, they are displayed as a collage on a large scale photo wall in the heart of Parramatta in Centenary Square. I love watching people looking for themselves or pointing to familiar faces.

As one passerby declared on seeing the photo wall:

Thanks for treating everyone the same, like we belong and are as deserving of recognition and dignity as others, instead of excluding us from being visible.

This feedback goes to the heart of the project that welcomed people from all walks of life to offer a view of Western Sydney that is far from the media stereotypes.

Fundamentally, the Parramatta Yearbook acts as a model for how cultural institutions and government can work together with artists to record and reflect community, create a sense of belonging and produce narratives about a place in transition that foregrounds the creativity of its citizens ahead of urban development.

The Parramatta Yearbook portraits are on public display in Parramatta’s Centenary Square until October 3, as well as in a 88-page downloadable yearbook from the Museum of Contemporary Art.

Cherine Fahd, Associate Professor of Visual Communication in the School of Design, University of Technology Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Hayao Miyazaki’s ‘Spirited Away’ continues to delight fans and inspire animators 20 years after its US premiere

When Hayao Miyazaki’s animated feature “Spirited Away” premiered in the U.S. 20 years ago, most viewers hadn’t seen anything like it.

Disney distributed the film. But as one critic pointed out, “Seeing just 10 minutes of this English version … will quickly disabuse any discerning viewer of the notion that it is a Disney creation.”

It tells the story of a 10-year-old girl named Chihiro who, when traveling with her parents, stumbles across what appears to be an abandoned theme park. As they explore, the parents are transformed into giant pigs, and Chihiro soon realizes that the park is occupied by strange, supernatural spirits. She ends up working at a bathhouse as she tries to figure out a way to free herself and her parents so they can return home.

The film went on to win an Oscar for Best Animated Feature. Twenty years later, it’s frequently listed as one of the best animated films of all time.

Yet as a scholar of manga and anime studies, I’m often struck by how popular the film became – and how fondly viewers remember it – given that so many of its elements would have been alien to American audiences.

The manga revolution

Many of the first anime films were inspired by manga, or Japanese comics.

Some of the hallmarks of modern manga, such as characters with big eyes, streaks to signal movement and different-sized panels to convey action, character and emotion more effectively, can be traced to the work of Osamu Tezuka, the so-called “God of Manga.”

Tezuka was influenced by his childhood and Japanese culture, but he was also inspired by American movies, television and comics.

When Tezuka was a child, he attended the performances of Takarazuka, an all-female theater group in Tokyo whose actresses tended to have well-lit, expressive eyes. His father also showed him American animation on a Pathe projector, and he was drawn to wide-eyed characters like Betty Boop and Bambi. Together, they inspired the big, expressive eyes that would become characteristic of Tezuka’s work.

Tezuka’s debut manga, titled “New Treasure Island,” was published in 1947 and became a hit with Japanese youth. Soon an entire manga industry sprang up, churning out vibrantly creative and emotionally relatable comics in a wide range of genres.

Miyazaki was 21 years old when Tezuka’s popular manga “Astro Boy” appeared on TV in Japan in 1963. NBC soon picked it up, airing 102 episodes in the U.S. and exposing millions of Americans to Japanese anime for the first time.

Over the ensuing decades, Americans enthusiastically embraced a range of manga and anime series through franchises like “Dragon Ball,” “Naruto” and “Demon Slayer.”

Doing anime differently

Miyazaki began his career in 1963 as an entry-level animator for Toei animation. He went on to work on a number of animated TV shows and films before founding his own production company, Studio Ghibli, with his longtime friend and collaborator, Takahata Isao, in 1985.

Anime is often based on successful manga series, and it involves creating a vibrant character kingdom and the construction of a world that often lends itself to spinoffs like movies, television shows, musicals, toys and massive merchandising opportunities.

In this sense, many of the films that came out of Studio Ghibli were not really traditional anime. Most lack the merchandizing tie-ins that have become ubiquitous in franchises like “Pokemon” and “Yu-Gi-Oh.” And while some of Ghibli’s films originated as manga, many of them did not. Miyazaki and his team also broke from industry norms by hiring artists as full-time staffers, rather than as underpaid freelancers.

As Miyazaki once said, “Animation has the potential to be far more than just about business, or merchandising, or selling character goods; it can have its own ambitions.”

When the line between good and evil blurs

When “Spirited Away” was released, the only feature-length Japanese animated film most Americans would have likely been exposed to in theaters was “Akira,” which had a limited run in 1990. The Academy of Motion Picture Arts and Sciences didn’t even award an Oscar for Best Animated Feature until 2001, because Disney and Pixar so thoroughly dominated the genre.

Compared with traditional Western animation, manga and anime tend to reflect a more adult and complicated view of morality, rather than the “good versus evil” paradigm common in children’s media.

“Spirited Away” centers on a spirit world that, while present in various other manga and anime films, challenges non-Japanese audiences. It is unclear whether the spirits will harm or help the protagonist. Miyazaki, New York Times film critic Elvis Mitchell wrote, captures “that fascinating and frightening aspect of having something that seems to represent good become evil.”

The world appears to be inspired by a class of spirits known as “kami” that are venerated in the religion of Shinto, although Miyazaki has noted that he invented his own spirits, rather than use previously known kami. “Demon Slayer,” a 2020 anime film that was a hit in the U.S., also contained characters from the spirit world.

As kami expert Matt Alt told me, “Only a place with countless shrines, each venerating their own locations and local deities, could have dreamed up something like ‘Spirited Away.’”

Yet thanks to the beauty of the film’s visuals – as well as the fact that, deep down, it contains universal storytelling tropes – Miyazaki can get viewers to buy into his world. No matter how strange a shape-shifting sludge spirit might appear to audiences, they can still relate to the spunky, and sometimes sullen, Chihiro.

As Miyazaki explained in an interview, the film’s idiosyncrasies ultimately enhance its universality: “No one waves weapons about or has showdowns using superpowers, but it’s still an adventure story. And while an adventure story, a confrontation between good and evil is not the main theme either. This is supposed to be the story of a young girl who is thrown into another world, where good people and bad are all mixed up and coexisting.”

“In this world,” he continues, “she undergoes rigorous training, learns about friendship and self-sacrifice and, using her own basic smarts, somehow not only survives but manages to return to our world.”

A lasting imprint

While Walt Disney and other American creators made a huge impression on Tezuka, the influences of anime can be seen in countless American films and TV shows.

This sort of cultural cross-pollination, which I detail in my book “Manga and Anime Go to Hollywood,” has been going on for decades.

Miyazaki’s films also have made a unique imprint on the imaginations of a generation of Western animators.

John Lasseter, the former chief creative officer of Pixar, has said that whenever he and his team got stuck for ideas, they would screen a Miyazaki film for inspiration. Domee Shi, the director for Pixar’s “Turning Red,” specifically cited “Spirited Away” as a huge influence. And a 2014 episode of “The Simpsons” even contained a tribute to Miyazaki.

Tezuka once said that a story was like a tree, which is only as strong as its roots.

To me, Miyazaki and his team achieved the highest level of filmmaking by not only creating gorgeous visuals, but by also crafting relatable lead characters, a compelling supporting cast and rich, enthralling worlds. Engaging viewers with a creative story arc, he always found a way to land with an timeless message.

Miyazaki noted that Chihiro ultimately returns to her ordinary world “not by vanquishing evil, but as a result of having learned a new way to live.”

This article has been updated to correct the class of Japanese spirits that those in “Spirited Away” evoke. It is “kami,” not “yokai.”

Northrop Davis, Professor of Media Arts, University of South Carolina

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Why do humans grow two sets of teeth? These marsupials are rewriting the story of dental evolution

You only get 52 teeth in your lifetime: 20 baby teeth, followed by 32 adult teeth.

It’s not like that for all animals. Some, like rodents, never replace their teeth. Others, like sharks, keep replacing them again and again.

So why do we humans replace our teeth only once? And how does the whole tooth replacement process work?

These are tricky questions, and we don’t have all the answers. But a new discovery about the strange tooth-replacement habits of the tammar wallaby, a small Australian marsupial, may help shed some light on this dental mystery.

Not everybody replaces teeth the same way

It has been long assumed modern mammals all replace their teeth the same way. However, advances in 3D scanning and modelling have revealed mammals with unusual tooth replacement, like the tammar wallaby (Macropus eugenii) and the fruit bat (Eidolon helvum).

These mammals have given us important clues as to how humans and other mammals have evolved from ancestors with continuous tooth replacement.

How do humans make and replace teeth?

Human teeth begin growing between the sixth and eighth week of an embryo’s development, when a band of tissue within the gums called the primary dental lamina starts to thicken. Along this band, clusters of special stem cells appear at the sites of future teeth, known as “placodes”.

The placodes then begin to grow into teeth, going through the bud, cap and bell stages along the way. They form into their final shape and harden with layers of dentine and enamel. Eventually, they will erupt through the gums. The incisors are the first to erupt, as early as 6 months old, which is why its called theteethingphase!

This generation of teeth, which grow from the primary dental lamina, are known as “primary dentition”, or baby teeth.

Secondary or adult teeth grow a little bit differently. An offshoot of tissue called the successional lamina grows out from the baby tooth, and that tissue develops the replacement tooth like an apple on a branch of a tree. Adult teeth begin to grow before we are born, but take many years for the full set to form and eventually appear.

Replacement occurs when the adult teeth get large enough that they finally push out the baby teeth and remain as the permanent set of teeth for the rest of our lives. The first molar usually erupts between 6 and 7 years of age, while our wisdom teeth are the last to appear (roughly between 17 and 21 years of age).

Most mammals replace their teeth once in the course of their lives, like we do. This is known as “diphyodonty” (two sets of teeth).

Some groups of mammals, such as rodents, don’t replace their teeth at all. These “monophyodonts” get by with the same set of teeth for their whole lives. There are also a few unusual mammals, such as echidnas, that don’t grow any teeth at all!

Learning from the wallaby

The tammar wallaby is also a diphyodont, replacing its teeth only once.

Scientists long assumed it replaced its teeth in the same way humans do, though historical notes going back as far as 1893 noticed unusual things about this marsupial’s tooth development. For starters, while we replace our incisors, canines and premolars, tammar wallabies only replace their premolars.

Recently my colleagues at Monash University and the University of Melbourne and I observed the teeth of tammar wallabies from the embryo through to adulthood. We used a technique called diceCT, which combines staining and CT scanning, and found something surprising.

Instead of replacement premolar teeth developing from the successional lamina, they were in fact delayed baby teeth developing from the primary dental lamina.

This means the tammar wallaby does not have any traditional tooth replacement. This discovery opens up a huge set of new questions. What exactly are these teeth?

One explanation for these delayed baby teeth could be a link to our ancestry of continuous tooth replacement.

Your teeth are millions of years in the making

Unlike mammals, most other animals, including fish, sharks, amphibians and reptiles, replace their teeth multiple times (they are “polyphyodonts”). Mammals lost this ability around 205 million years ago.

The reason we stop making teeth is because our dental lamina degrades after our second set are made, while it remains active in polyphyodonts.

Interestingly, in modern and fossil polyphyodonts the replacement teeth often develop in groups of alternating waves, known as “Zahnreihen”.

While the tammar only replaces its premolars, these delayed baby teeth could represent the presence of the Zahnreihen still occurring in modern mammals.

This gives us a clue about how we have evolved from ancestors with continuous tooth replacement: by modifying and reducing a system that is hundreds of millions of years old.

Research has also found that fruit bats (Eidolon helvum) make replacement teeth in unusual ways, including growing them in front of the baby tooth, behind it, beside it, or splitting off from it.

This is exciting because, together with the tammar, it shows there may well be a wealth of tooth replacement diversity across mammals happening right under our noses – or our gums!

Qamariya Nasrullah, Postdoctoral Research Associate in Evolutionary Morphology, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

In The Australian Wars, Rachel Perkins dispenses with the myth Aboriginal people didn’t fight back

First Nations people please be advised this article mentions colonial violence towards Aboriginal and Torres Strait Islander people.

The Australian Wars is a new three-part TV series directed and produced by Arrernte and Kalkadoon nations filmmaker Rachel Perkins.

Perkins travels across vast territory to capture key aspects of a war that lasted more than 100 years, from the landing of the First Fleet in 1788 until the 1920s.

The series traces some of the key phases, sites and underlying features of frontier wars here on home soil.

It sets out to understand why the war was never declared, why the British didn’t follow their own laws, and the tactics and strategies Aboriginal people deployed defending their land and survival.

Perkins asks us to consider this difficult history, why there are only a handful of monuments to this warfare, and how it should be memorialised.

To ask these questions, Perkins deploys stunningly shot re-enactments, archives, artefacts, biography, expert evidence and uses place to great effect.

The series treats the viewer with the ability to critically reflect and ask why we still struggle to come to terms with this history.

The frontier wars

The “frontier wars” were the conflicts between Europeans and Aboriginal people over access to land the British sought to occupy exclusively without any agreement, treaty or settlement. This series emphasises Aboriginal people resisted these wars in multiple ways, including warfare. Aboriginal people are still resisting these wars today, in the courts.

The Australian Wars is an important contribution to truth-telling. Perkins provides a public reckoning with the means by which the British Empire – followed by independent democratic Australian governments – managed to grab the entirety of the land assets of the continent.

The dominant narrative of Australian settler colonialism was once sunny tales of possession, sustained by hard toil. Aboriginal acts of resistance, refusal and warfare were somehow miraculously omitted.

Only in recent decades has a more truthful account of the past emerged. New conversations and responsibility are slowly navigating the realities of the frontier, the shared history of “both sides” and how the past can be remembered.

Reconciliation Australia’s “Reconciliation Barometer” survey identified only 64% of non-Indigenous Australians believed the frontier wars occurred. Some 30% of respondents were unsure and 6% rejected the factual accuracy of significant aspects of Australia’s colonial history.

The Australian War Memorial, once tasked with considering how to reflect frontier wars in Australia’s story, rejected any inclusion of the frontier wars in its exhibitions.

The documentary returns to the theme of rejecting this part of Australia’s history and asks: how can the frontier wars be remembered and memorialised?

Perkins reminds us that as many people – both black and white – died in the frontier wars as did in overseas conflicts featured at the Australian War Memorial.

The moving frontier

The Australian Wars draws together experts of Australian history, detailed studies of the expansive colonial records, the oral testimony of survivors’ descendants and new archaeological research.

With this trove of references, Perkins reveals the extent and breadth of violence, the global networks of military men and the strategies they honed on the frontier, and the technology that came to enable this.

Ultimately, we learn unfettered access to the land resource was the driving factor. The rule of law, claims of humanitarianism and Christianity were readily dispensed with in pursuit of land.

Perkins begins this story in the nation’s capital at the War Memorial. She then follows the moving frontier from the Sydney settlement to Tasmania and crossing Bass Strait. The story then moves with rapid pace from south to north and across the top end to the Kimberley, as settlers expanded across landscapes in always violent encounters.

She dispenses with the abiding myth Aboriginal people didn’t fight back.

In each location Perkins focuses on, we see different strategies deployed, tactical advantage held at times by Aboriginal people, the fear and terror struck in the settlers, and the military actors and strategy that underpinned the colonial settlements.

By the third episode, as the frontier heads north, settlers take lessons from Sydney, Tasmania and the New South Wales grasslands country. Moving with much greater speed aided now by horses, the settlers recruited skilled Native Mounted Police, used repeating rifles and developed systems and infrastructure to confine Aboriginal people to prisons.

But the Aboriginal peoples whose lands were being invaded were fast developing new tactics.

In Queensland alone it is estimated 72,000 Aboriginal men, women and children were killed.

How do we remember?

The series prompts us to ask: if not war, then what do we call the process by which the land, once all carefully delineated and peopled, is occupied by settlers?

How do we remember this and memorialise those who died?

Perkins tells us this violence was often very well documented. This violence was acted against people whose eyes you could see. Yet from Lake George, just outside the nation’s capital, to the Sydney wars and massacres, Tasmania, Queensland and to the Kimberley, sites of violence are overwhelmingly unmarked, unobserved, save for colonial names: “Blackfellows Bones”, “Victory Hill”.

The silence continues.

Leading Australian historian Henry Reynolds says the frontier wars are our most important war because of where they were fought and what they were about: the outcome determined the ownership and sovereign control of a whole continent.

As he comments in the series “what can be more important than that to us?”

The Australian Wars is on SBS and SBS on Demand from today.

Heidi Norman, Professor, Faculty of Arts and Social Sciences, University of Technology Sydney and Anne Maree Payne, Lecturer, Centre for the Advancement of Indigenous Knowledges, University of Technology Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Deepfake audio has a tell – researchers use fluid dynamics to spot artificial imposter voices

Imagine the following scenario. A phone rings. An office worker answers it and hears his boss, in a panic, tell him that she forgot to transfer money to the new contractor before she left for the day and needs him to do it. She gives him the wire transfer information, and with the money transferred, the crisis has been averted.

The worker sits back in his chair, takes a deep breath, and watches as his boss walks in the door. The voice on the other end of the call was not his boss. In fact, it wasn’t even a human. The voice he heard was that of an audio deepfake, a machine-generated audio sample designed to sound exactly like his boss.

Attacks like this using recorded audio have already occurred, and conversational audio deepfakes might not be far off.

Deepfakes, both audio and video, have been possible only with the development of sophisticated machine learning technologies in recent years. Deepfakes have brought with them a new level of uncertainty around digital media. To detect deepfakes, many researchers have turned to analyzing visual artifacts – minute glitches and inconsistencies – found in video deepfakes.

Audio deepfakes potentially pose an even greater threat, because people often communicate verbally without video – for example, via phone calls, radio and voice recordings. These voice-only communications greatly expand the possibilities for attackers to use deepfakes.

To detect audio deepfakes, we and our research colleagues at the University of Florida have developed a technique that measures the acoustic and fluid dynamic differences between voice samples created organically by human speakers and those generated synthetically by computers.

Organic vs. synthetic voices

Humans vocalize by forcing air over the various structures of the vocal tract, including vocal folds, tongue and lips. By rearranging these structures, you alter the acoustical properties of your vocal tract, allowing you to create over 200 distinct sounds, or phonemes. However, human anatomy fundamentally limits the acoustic behavior of these different phonemes, resulting in a relatively small range of correct sounds for each.

In contrast, audio deepfakes are created by first allowing a computer to listen to audio recordings of a targeted victim speaker. Depending on the exact techniques used, the computer might need to listen to as little as 10 to 20 seconds of audio. This audio is used to extract key information about the unique aspects of the victim’s voice.

The attacker selects a phrase for the deepfake to speak and then, using a modified text-to-speech algorithm, generates an audio sample that sounds like the victim saying the selected phrase. This process of creating a single deepfaked audio sample can be accomplished in a matter of seconds, potentially allowing attackers enough flexibility to use the deepfake voice in a conversation.

Detecting audio deepfakes

The first step in differentiating speech produced by humans from speech generated by deepfakes is understanding how to acoustically model the vocal tract. Luckily scientists have techniques to estimate what someone – or some being such as a dinosaur – would sound like based on anatomical measurements of its vocal tract.

We did the reverse. By inverting many of these same techniques, we were able to extract an approximation of a speaker’s vocal tract during a segment of speech. This allowed us to effectively peer into the anatomy of the speaker who created the audio sample.

From here, we hypothesized that deepfake audio samples would fail to be constrained by the same anatomical limitations humans have. In other words, the analysis of deepfaked audio samples simulated vocal tract shapes that do not exist in people.

Our testing results not only confirmed our hypothesis but revealed something interesting. When extracting vocal tract estimations from deepfake audio, we found that the estimations were often comically incorrect. For instance, it was common for deepfake audio to result in vocal tracts with the same relative diameter and consistency as a drinking straw, in contrast to human vocal tracts, which are much wider and more variable in shape.

This realization demonstrates that deepfake audio, even when convincing to human listeners, is far from indistinguishable from human-generated speech. By estimating the anatomy responsible for creating the observed speech, it’s possible to identify the whether the audio was generated by a person or a computer.

Why this matters

Today’s world is defined by the digital exchange of media and information. Everything from news to entertainment to conversations with loved ones typically happens via digital exchanges. Even in their infancy, deepfake video and audio undermine the confidence people have in these exchanges, effectively limiting their usefulness.

If the digital world is to remain a critical resource for information in people’s lives, effective and secure techniques for determining the source of an audio sample are crucial.

Logan Blue, PhD student in Computer & Information Science & Engineering, University of Florida and Patrick Traynor, Professor of Computer and Information Science and Engineering, University of Florida

This article is republished from The Conversation under a Creative Commons license. Read the original article.