This is an article from Curious Kids, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. You might also like the podcast Imagine This, a co-production between ABC KIDS listen and The Conversation, based on Curious Kids.

Why do we have tonsils????? – Ryan, age 10, Blacktown.

Thanks Ryan. I am guessing, based on the number of question marks you’ve used, that your tonsils might have caused you some trouble. You’re not alone.

The truth is that unless you are a baby, you don’t really need tonsils. Many people have them removed and live happily without them. I’ll tell you why, but first I have to explain what your tonsils actually are.

Waldeyer’s ring

The technical term for your tonsils is “palatine tonsils”, which means the tonsils of the palate. These lumpy things sit on either side at the back of our mouths. The palatine tonsils are one pair of a set of four tonsils that form a circle at the top of our throat.

At the back of our nose, we have the adenoids. They are another type of tonsil tissue, technically called the “nasopharyngeal tonsils”. There is also a blanket of tonsil tissue over the back of our tongue called the “lingual tonsils”, which we can’t normally see. The adenoids and the tonsils are linked by a thin strip of tonsil tissue on each side; these are called the “tubal tonsils”. Together this whole ring of tonsil tissue is called “Waldeyer’s ring”, named after a nineteenth century German anatomist.

Tonsils are important for immune defence

Waldeyer’s ring forms part of our immune system, along with our lymph glands (which are either side of your neck).

In early life, the lymph glands are not completely developed, and our bodies rely on our tonsils to trap bugs and foreign material that we either breathe in or swallow. By trapping these particles, the body begins to recognise them as potentially dangerous things and produces things called antibodies to kill them so they can’t harm us. Tonsil tissue is particularly good at trapping these particles as it has valleys and holes (called crypts) which increase its surface area.

Tonsil tissue is particularly important in the first six months of life. After this, our lymph glands take over most of the work and the tonsils are essentially out of a job.

Tonsil trouble

As we get older, food and germs can still land in the valleys and crypts. They can then cause infections to develop, which lead to a sore throat or tonsillitis. Some infections can also cause the tonsils to grow in size. Huge tonsils and adenoids can block the airway and cause snoring or swallowing and speech problems. As nutrition and immunisation has improved, kids get tonsillitis less and less these days. Usually, an ear nose and throat surgeon like me gets called in to intervene more for obstruction (blockage) than repeated infections.

Shrinking tonsils

If tonsils are a problem, an ear, nose and throat surgeon can remove them by doing an operation. If they are simply too large, they can be shrunk down using special instruments which remove the valleys and crypts. This leaves a thin bit of tonsil tissue behind.

Shrinking the tonsils down reduces the amount of pain kids get and also reduces the chances of bleeding after the operation. The downside is that, in rare cases, the bit we leave behind can get infected, or can regrow - although this is uncommon.

People sometimes worry that by removing the tonsils, we may be more likely to get infections. This is not actually the case. The lymph glands take over the role of protecting us.

If tonsils are too big or keep getting infected, they end up being more trouble than they’re worth.

Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. They can:

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Simon Carney, Professor of Otolaryngology - Head & Neck Surgery, Flinders University

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

Curious Kids is a series for children. If you have a question you’d like an expert to answer, send it to curiouskids@theconversation.edu.au You might also like the podcast Imagine This, a co-production between ABC KIDS listen and The Conversation, based on Curious Kids.

Who came up with the first letters? – Chase, age 6, Adelaide, SA.

This is a great question, Chase!

We don’t know exactly who invented the first letters. The Phoenician alphabet is considered the first known alphabet, but experts think it has its roots in an earlier Old Canaanite tradition.

You’re probably wondering: who are the Phoenicians? What does Old Canaanite mean? You’re right – these are unfamiliar terms to most people today. To explain, let’s look a little deeper into human history.

Writing is a pretty recent invention

Humans began to communicate using speech some 50,000 years ago but writing has only been a part of the human story for the last 5,000 years.

Writing wasn’t just invented once by a single person. Many different ancient societies invented writing at different times and places.

It seems writing was such a great idea, it just kept being created by humans living in all different parts of the world.

Writing was invented in different places

Thousands of years ago, people lived in Mesopotamia (near the modern day Middle East), Egypt, China, and Mesoamerica (near what we now call Central America). These different groups all invented their own kind of writing independently.

For example, the ancient Mayans in Mesoamerica had their own written language, which would have looked strange to the Sumerian people who lived in Mesopotamia. They had their own writing style, called cuneiform.

There were also ancient people who lived in the Indus River valley (near what we now call Pakistan and India) who also developed their own kind of writing. Ancient people in Elam (near what we now call Iran) invented another type of writing.

There is also the mysterious Rongorongo script from the people of Easter Island (also called Rapa Nui), which no one has been able to read – at least, not yet!

Borrowing and copying

There was also plenty of copying and borrowing among ancient writers who came across other writing systems when they travelled.

This is true for the English letters we write with today. We call these letters the Roman alphabet because a long time ago, they were used by the people of ancient Rome (in Italy) to write Latin

In fact, these Roman letters are still used to write Latin, just like in spells in the Harry Potter books and films.

From cuneiform to alphabets

Many early styles of writing involved hundreds of symbols, pictures, and signs.

In one of the earliest types of writing, called cuneiform, a single sign could be used for a word, or a sound, or even give a hint about the type of word to follow. These scripts could be quite difficult to read.

Then came alphabets. An alphabet is a set of letters or symbols that can represent the sounds we make when we talk. The different parts of the alphabet can be put together to make different words, just like LEGO pieces that can be clicked together in different ways.

You know our alphabet, I’m sure, but other languages may have their own alphabet.

The Canaanites lived in an area of the ancient world called the Levant, in what we now call the Middle East.

The Old Canaanite script appeared around 3,500 years ago, and the Phoenician alphabet came after.

Unlike the art of writing more broadly, it is thought that all known alphabets (including our own) are in some way related to the Phoenician system.

Back to the Phoenicians

The Phoenicians lived near what we now call the Middle East. They invented an alphabet with 22 consonants and no vowels (A, E, I, O or U). Vowels only became part of the alphabet much later.

The Phoenicians were great traders, buying and selling things like wood, perfumes, honey and a type of purple dye worn by kings and queens.

The busy trading of the Phoenicians meant their inventions quickly spread to their trading partners. People soon realised writing was a good way to keep track of what they bought and sold.

So as you can see, writing has changed a lot over time. And it is still changing today!

This article has been updated.

Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to curiouskids@theconversation.edu.au

Please tell us your name, age and which city you live in. We won’t be able to answer every question but we will do our best.

Louise Pryke, Lecturer, Languages and Literature of Ancient Israel, Macquarie University

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

This is an article from Curious Kids, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!

Why is the Earth round? – Zoe, age 3, Sydney.

Thank you, Zoe, for your great question. Asking questions like this is a really important part of being a scientist.

Imagine the Earth pulling everything it is made up of, all of its mass, towards its centre. This happens evenly all over the Earth, causing it to take on a round shape. Let me explain what I mean by that.

To understand why the Earth is round we need to look at two things - mass and gravity.

Every single thing in the universe has mass - from the biggest star to a tiny grain of sand. People, too, have mass. The more big and dense something is, the more mass it has. So an elephant would have more mass than a mouse, for example.

More mass means more gravity

While you might not be able to see it, all objects with mass are actually being pulled towards each other by a force called gravity. The bigger the mass of something, the stronger its pull.

Have you ever wondered why if you drop something, it falls towards the Earth and not up into the sky? Or the reason why we’re all stuck to the ground?

That’s because of gravity. Because the mass of the Earth is so much bigger than the mass of people (or spoons, or vases, or water), we’re all strongly pulled towards it, which is why it feels like we’re stuck to the earth’s surface.

Not everything in space is round

Part of what makes a planet a planet is its round shape. But most things in space are not perfectly round at all! In fact, some things are very lumpy. The reason for this is the way planets are made.

Planets are made of rock, ice, and gas. Before becoming a planet, the rocky and icy parts are small lumps, no bigger than sand grains, moving around the young Sun.

Over millions of years, gravity pulled the small rocky and icy parts towards each other until they started to stick together. Eventually these small parts grew from the size of sand into the size of mountains.

These mountains of rock and ice are fluffy, like giant dirty snowballs. So the small mass - and weak gravity - of the whole mountain is unable to overcome the hard shape of the rock and ice lumps to become round.

Fluffy mountains like these got swept together billions of years ago to make the planets we recognise today. But some of them are still minor objects in the Solar system. These bits of leftover planet-building material, called asteroids and comets, have very lumpy shapes. Some are shaped like potatoes and others like eggs.

The largest of these minor bodies, such as Ceres and Pluto, have enough gravity to look round like a planet. They are called dwarf planets. Some, like Haumea, spin very fast, giving them an stretched shape, like this:

Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. You can:

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Jonathan P. Marshall, Vice Chancellor's Post-doctoral Research Fellow, UNSW

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This is an article from Curious Kids, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!

Bula! My name is Emelia and I am 6 years old. My little brother and I live in Fiji and we love listening to the Imagine This podcast! We love the episode about why cats don’t wear shoes. I would like to know why man lions have manes and lady lions don’t?– Emelia, age 6, Fiji.

Thank you, Emelia, for your very interesting question.

For a long time, people thought that boy lions had big shaggy manes to protect the area around their necks from being bitten or scratched during hunts and fights.

However, as time passed, scientists began to see that this idea didn’t really make sense.

The first reason it didn’t make sense was that when lions fight each other, they don’t usually attack the neck at all. Instead, when they get into fights, they tend to bite along the back and hips. That means it is unlikely their neck would be close enough to another lion’s teeth to get bitten. So it wouldn’t make much sense for the mane to protect a place that wasn’t in danger.

Another big reason that people no longer think that manes are there to protect boy lions is because of the way lions hunt. When looking for food, lions hunt in a group called a pride. But both boy lions and girl lions in the pride work together when they hunt. So if manes were supposed to be for protection, then why wouldn’t girl lions and boy lions both have manes?

So because scientists found that their old ideas couldn’t be true, they came up with new possibilities that would fit with what they were seeing. This happens all the time in science.

Instead of being for protection, people now think that the boy lion’s mane shows the girl lions how healthy and strong he is. The idea is that the stronger and healthier a boy lion looks, the better the girl lion’s babies will grow since they would have a dad with good genes. (Genes are the “recipe” that tells a baby animal or plant how to grow, so having parents who are strong and healthy makes you more likely to grow up strong and healthy.)

Some studies show that female lions even prefer darker coloured manes to bigger manes. A pale mane might mean the lion is experiencing stress – for example, they might not be getting enough of the right foods or they might be feeling sick. The dark colour seems to show that the boy lion is under less stress.

In the same way that dark clothes make us hotter than white clothes would, the dark mane shows that the lion can do well in hot weather.

This is really important in the warm climates where lions live.

Lions aren’t the only animals that choose their mates based on how they look. For instance, girl peahens tend to like boy peacocks with the biggest and showiest feather displays.

So scientists now think that a lion’s big puffy mane probably isn’t there for protection.

Instead, we think the mane, and especially its colour, helps the boy lions show the girl lions how healthy and strong they are. Then the girl lions will know who will be a good dad for her babies.

Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. They can:

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Nadya Sotnychuk, PhD candidate, University of New England

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

This is an article from Curious Kids, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!

What causes windy weather? – Jake, aged 8, Melbourne.

Thank you for your great question, Jake.

Wind is just moving air, and air is a collection of different gases. It’s mostly one type of gas, called nitrogen, but also lots of others, including oxygen – which we need to live.

When air is under pressure, it starts to move – and that causes wind. I’ll explain what I mean by “under pressure”.

Imagine you are blowing up a balloon. As you blow more air into the balloon, the pressure builds inside. If the pressure gets too great, the balloon could pop because the air has nowhere to move.

Just like the balloon, we don’t like to be under pressure, either. Think of when your brother or sister or slightly annoying cousin gives you a great big bear hug. You feel pressure because you’re getting squeezed. Sometimes that can be nice, but when the squeezing gets too much the best way to get comfortable again is to break free and run. It’s the same with air: when it’s under pressure, it tries to escape.

When the air inside a balloon is under pressure and you take your fingers off the neck part of it, the air rushes out – often with a bit of an embarrassing farty noise. Well, that air rushing out is wind. (And, let’s be honest, it’s why another name for a fart is “breaking wind”.)

In the atmosphere, the same thing happens. When pressure builds up in one place, the air rushes to another place where there is less pressure.

But what is causing this pressure in the atmosphere?

Well, as the sun heats up the surface of the Earth, some areas get warmer and others stay cooler. On the whole globe, for instance, the North and South Poles are really cold. This is because sunbeams pass over the top, so not much sunlight actually hits the ground. Compare this to the equator, where temperatures are really warm, because the sunbeams are hitting it from directly above.

As you may know, warm air rises - just like when you see hot steam coming out the top of your kettle or a cooking pot at home.

My old teacher used to say: “You don’t get something for nothing, Andrew!” What he meant was that if air goes up in one place, it must come down in another place. That other place will be where the air is not rising, and that’s normally where the cool areas are.

As this happens and the air comes down, it hits the ground and starts to build up. When that air piles up too much, that pile of air will collapse and spread out, just like air rushing out of a balloon.

That air will rush towards the area that doesn’t have a big mound of air built up, and that will usually be a warm place where the air is rising.

You can feel this happening at the beach in summer, where the sun heats up the sand more than the water. As heat builds up the air rises over the land and starts to fall over the ocean. Soon there is more air over the ocean than the land, and a breeze starts as that air pile collapses.

So, put simply: wind is just air moving from one place where there is high pressure to another place where there is low pressure (a smaller pile of air).

Often, that’s from where it is cooler to where it is hotter. And, thankfully, it rarely makes that farty sound.

Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. They can:

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Andrew B. Watkins, Manager of Long-range Forecast Services, Australian Bureau of Meteorology

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This is an article from Curious Kids, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!

Why do some people find some foods yummy while others find the same foods taste yucky? – Emilia Bennett, aged 7, and Jessamy Bennett, aged 10.

Some people love coriander, others hate it. You might like olives, but maybe your dad thinks they’re disgusting. To understand why, you have to delve a little into the science of evolution, chemistry and biology.

Being able to taste helps you choose foods that provide the energy or nutrients your body needs, and avoid eating things that provide no energy, like a bicycle*.

In other situations, a bad taste can be a warning sign to put down harmful or toxic foods. That’s why some poisonous things, like certain wild mushrooms, have a sharp or bitter taste.

Why do I like blue cheese, but my friends don’t?

There are many reasons why you may like a food and your friend might not.

The first is your own DNA sequence. A DNA sequence is like a recipe that tells your body how to make proteins, which are one of the most important building blocks in your body.

Each person has their own DNA sequence, or recipe, that is different to everyone else. DNA helps determine how you taste and smell and the messages sent to your brain about what’s nice and what’s not. So each of us taste the flavour of food differently.

Scientists have even worked out that differences in your DNA can affect how you feel about the smell of blue cheese (specifically, there’s a chemical called “isovaleric acid” that helps your body decide how it feels about that particular smell).

And you can also blame your DNA for how you feel about the taste of brussels sprouts or broccoli.

But it’s not just about what genes you’re born with. It also depends on how familiar you are with the food and if you have eaten it before. Vegemite is a good example, where if you have grown up with it (and if you know that you’re only supposed to eat a little bit at a time), you are more likely to think it tastes nice.

Finally, your environment can impact your choices. If you are feeling unwell or you just ate food, your tastes can change – you might suddenly feel like you just do not want anything spicy or greasy that day.

These three reasons (your DNA, past food experiences and your environment) help decide the foods you like or dislike.

The foods you like and dislike will change during your life

Taste preferences start building before you were born, where the food flavours your mum ate were sent to you as you were growing in her womb. This first-taste experience has an impact on your food choices in childhood. But your likes and dislikes are not permanent; as we age, our taste changes.

We may also learn to like foods that taste yucky by trying them again and again or we can dislike foods when we have a bad experience with them – such as if a bad egg makes you sick and you decide never to eat eggs again, even though you liked them before.

As you can see, understanding why you like the foods that others find yucky is complicated and there are many scientists across the globe trying to understand why.

Now you have learnt that tastes can change, remember that the foods you hate now may one day end up being your favourites.

*CSIRO does not condone the eating of bicycles.

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Nicholas Archer, Research Scientist, Sensory, Flavour and Consumer Sciences, CSIRO

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This is an article from Curious Kids, a series for children. The Conversation is asking kids to send in questions they’d like an expert to answer. All questions are welcome – serious, weird or wacky!

I lost my first tooth on Tuesday. I was fiddling with it while I was watching TV. I had a mouthful of blood! It soon stopped bleeding. When I looked at the bottom of my tooth the edge was very spiky! Can you tell me why? – Nicholas, age 6, North Sydney.

Thanks for the great question, Nicholas.

At around six months of age, babies usually start getting teeth. The first to appear are the thin front teeth, called incisors. New teeth keep erupting from the gums until around two or two-and-a-half years of age. The molars - the flat grinding teeth at the back of the mouth - come up last. In total, you end up with 20 baby teeth.

At around six years of age, the bottom incisors start to loosen. When adult teeth start to grow, they cause the roots of the baby teeth (which are hidden under the gum and hold the teeth to the jaw) to be “eaten away” to make space for the adult teeth working their way up into the mouth.

Soon the roots of the baby teeth are eaten away until they start to get wobbly. Soon it gets so wobbly it gets knocked out when you eat something or brush your teeth. Or you might twist it out while you’re watching TV, just like you did.

There often is some blood because the wobbly tooth is still attached to the gum, so that gets torn when the tooth is lost and it bleeds a little. There often seems to be more blood than there really is because it mixes with your spit.

The edges of your tooth were sharp because when the root of the baby tooth is being eaten away by the growing adult teeth, it tends to start from the middle of the root. Something like a rough shell edge is left when most of the root has been absorbed and the tooth is finally lost.

When you look at an X-ray, you can see that the baby teeth still have most of their roots, so they look very different to your fallen tooth. You can also see that the growing adult teeth don’t have complete roots - they still grow for a while after the tooth erupts into the mouth.

Some people lose teeth a bit earlier and some a bit later than the normal time, but this is usually OK. However, if your first set of teeth start to fall out before you turn five, then it is worth seeing a dentist who is good at treating kids.

Soon, Nicholas, you will start to get new teeth at the back of your mouth. They’re called the first permanent molars and there are four of them, one in each corner.

These teeth will erupt without a baby tooth falling out, as they are appearing in spots that are currently empty. After that happens, you will have 24 teeth, until you start losing more baby teeth when you are nine or 10.

Then you’ll get more molars at the back (these guys are called the second permanent molars) when you are around 12, and then third permanent molars when you are around 18 or so. These ones are often called wisdom teeth.

Baby teeth are really important. They allow you to chew food, have a nice smile, and help keep space for adult teeth. So it is good to avoid lots of sugar and brush your teeth twice a day with fluoridated toothpaste.

Hello, curious kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to us. They can:

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David Manton, Professor of Paediatric Dentistry, The University of Melbourne

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