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.

If evolution is real, then why is it not happening now? – Dee, Memphis, Tennessee

Many people believe that we humans have conquered nature through the wonders of civilization and technology. Some also believe that because we are different from other creatures, we have complete control over our destiny and have no need to evolve. Even though lots of people believe this, it’s not true.

Like other living creatures, humans have been shaped by evolution. Over time, we have developed – and continue to develop – the traits that help us survive and flourish in the environments where we live.

I’m an anthropologist. I study how humans adapt to different environments. Adaptation is an important part of evolution. Adaptations are traits that give someone an advantage in their environment. People with those traits are more likely to survive and pass those traits on to their children. Over many generations, those traits become widespread in the population.

The role of culture

We humans have two hands that help us skillfully use tools and other objects. We are able to walk and run on two legs, which frees our hands for these skilled tasks. And we have large brains that let us reason, create ideas and live successfully with other people in social groups.

All of these traits have helped humans develop culture. Culture includes all of our ideas and beliefs and our abilities to plan and think about the present and the future. It also includes our ability to change our environment, for example by making tools and growing food.

Although we humans have changed our environment in many ways during the past few thousand years, we are still changed by evolution. We have not stopped evolving, but we are evolving right now in different ways than our ancient ancestors. Our environments are often changed by our culture.

We usually think of an environment as the weather, plants and animals in a place. But environments include the foods we eat and the infectious diseases we are exposed to.

A very important part of the environment is the climate and what kinds of conditions we can live in. Our culture helps us change our exposure to the climate. For example, we build houses and put furnaces and air conditioners in them. But culture doesn’t fully protect us from extremes of heat, cold and the sun’s rays.

Here are some examples of how humans have evolved over the past 10,000 years and how we are continuing to evolve today.

The power of the sun’s rays

While the sun’s rays are important for life on our planet, ultraviolet rays can damage human skin. Those of us with pale skin are in danger of serious sunburn and equally dangerous kinds of skin cancer. In contrast, those of us with a lot of skin pigment, called melanin, have some protection against damaging ultraviolet rays from sunshine.

People in the tropics with dark skin are more likely to thrive under frequent bright sunlight. Yet, when ancient humans moved to cloudy, cooler places, the dark skin was not needed. Dark skin in cloudy places blocked the production of vitamin D in the skin, which is necessary for normal bone growth in children and adults.

The amount of melanin pigment in our skin is controlled by our genes. So in this way, human evolution is driven by the environment – sunny or cloudy – in different parts of the world.

The food that we eat

Ten thousand years ago, our human ancestors began to tame or domesticate animals such as cattle and goats to eat their meat. Then about 2,000 years later, they learned how to milk cows and goats for this rich food. Unfortunately, like most other mammals at that time, human adults back then could not digest milk without feeling ill. Yet a few people were able to digest milk because they had genes that let them do so.

Milk was such an important source of food in these societies that the people who could digest milk were better able to survive and have many children. So the genes that allowed them to digest milk increased in the population until nearly everyone could drink milk as adults.

This process, which occurred and spread thousands of years ago, is an example of what is called cultural and biological co-evolution. It was the cultural practice of milking animals that led to these genetic or biological changes.

Other people, such as the Inuit in Greenland, have genes that enable them to digest fats without suffering from heart diseases. The Turkana people herd livestock in Kenya in a very dry part of Africa. They have a gene that allows them to go for long periods without drinking much water. This practice would cause kidney damage in other people because the kidney regulates water in your body.

These examples show how the remarkable diversity of foods that people eat around the world can affect evolution.

Diseases that threaten us

Like all living creatures, humans have been exposed to many infectious diseases. During the 14th century a deadly disease called the bubonic plague struck and spread rapidly throughout Europe and Asia. It killed about one-third of the population in Europe. Many of those who survived had a specific gene that gave them resistance against the disease. Those people and their descendants were better able to survive epidemics that followed for several centuries.

Some diseases have struck quite recently. COVID-19, for instance, swept the globe in 2020. Vaccinations saved many lives. Some people have a natural resistance to the virus based on their genes. It may be that evolution increases this resistance in the population and helps humans fight future virus epidemics.

As human beings, we are exposed to a variety of changing environments. And so evolution in many human populations continues across generations, including right now.

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.

Michael A. Little, Distinguished Professor Emeritus of Anthropology, Binghamton University, State University of New York

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.

How do shells get made? – Ida, age 6.

Thank you, Ida, for this excellent question. It is good that you are noticing the world around you and asking questions about how it came to be that way.

Common types of shells include seashells, land snail shells, turtle shells or even crab shells. All those animals make their shells in different ways, but my research is all about the sea so today we will focus on seashells.

All those seashells you find on the beach were actually once home to small, soft-bodied creatures called molluscs. Clams, pipis, scallops, mussels and oysters are all different types of molluscs.

Not all molluscs have shells. For example, an octopus is also a mollusc and it doesn’t have a shell.

But the molluscs who do have shells have to build their own shell from scratch. And they keep building it their whole life.

How to build a shell

A few days after baby molluscs come out from tiny eggs, they start building their shell, layer after layer.

They use salt and chemicals from the sea (such as calcium and carbonate). They also use other ingredients from their own bodies (such as special chemicals called proteins that help them build the shell).

The part of the mollusc’s body that is in charge of building the shell is called the “mantle”. The mantle builds a kind of frame first, using proteins to make it very strong. It then fills it in with calcium and carbonate. These are some of the same chemicals your body uses to make your bones.

To make space for their growing body, molluscs have to gradually enlarge and extend their shells by adding new layers of those building blocks – calcium, carbonate and proteins.

The newest part of the sea snail’s shell, for example, is around the opening where the animal pokes out.

Seashells are important for the planet

If damaged, the mollusc’s body can produce more proteins, calcium and carbonate to repair the broken part of the shell.

When a mollusc dies, the soft body disappears but its shell remains and eventually washes up on the shore. This is how seashells end up on the beach.

As you know, there are many types of seashells out there and lots of different shapes, sizes and colours of shell.

Over time, molluscs have grown to have the type of shell that helps it best survive in its environment. For example, some shells help protect the mollusc against animals that want to eat it, while others are designed to make it easier for the mollusc to dig down fast to get away. The colour of the shell depends mainly on what the mollusc has eaten.

Before you collect seashells from the beach, think about how important they are to the planet.

Seashells may not be home to molluscs anymore, but they can still be used as homes by hermit crabs or young fish. Birds also use shells to build their nests. So you can see, some animals need the shells more than we do.

A good choice is to take pictures of them instead of taking them home!

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.

Aurelie Moya, Research Fellow at the ARC of Excellence for Coral Reefs Studies, James Cook University

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

Do whales fart and sneeze? — Guy, age 8, Sydney

I’ve waited a long time for a question like this! I usually talk about whale snot for my research (yes, whales have snot), and I’m so excited to look into this, too.

Let’s start with the tail end first: farts

Yes, whales do fart. Can you imagine the size and bubbles of a fart from the world’s biggest animal, the blue whale?

I’m yet to experience this, but I know of some lucky scientists who have seen a humpback whale fart. They tell me it looks like bubbles coming out underneath its body near the tail. That’s where the whale bum is — the smellier blowhole.

Whales are mammals, just like us. This means they breathe air, give birth to live young, provide their young with milk and have hair, usually in the form of whiskers around their mouth. They also have digestive processes to help break down their food.

Unlike us, whales don’t chew their food but swallow it whole. Baleen or toothless whales, for example, use long hair-like structures to feed on krill and fish. Their food is later broken down across four stomach chambers.

As their bodies break this food down (via stomach acid), it produces gases, which are released as farts and eventually poo.

In fact, whale poo is one of the coolest looking in the animal kingdom. Blue whale poo can be bright orange!

Back to the top end: do whales sneeze?

The short answer, no.

Unlike us, whales need to think about breathing. When they want to take a breath, they need to swim to the surface. If they don’t, they could drown.

This means whales also sleep differently to us. They can rest different parts of their brain at a time, and take naps before rising to the surface to breathe.

And unlike us, they can’t breathe through their mouth and instead use their blowhole or nose to breath. This is like having an inbuilt snorkel on top of their head.

This makes it much easier for them to swim, breathe and eat — all at the same time. And they don’t have to worry about food going down the wrong way as their air and lung passages are separated.

We sneeze automatically and involuntarily if something tickles our nose. If whales get something caught in their noses, they could clear it using a big exhale through their blowhole, like blowing their nose. This would serve a similar function to our sneezing.

BUT, if a whale were to sneeze…

It would be big! For comparison, an adult human’s lungs can hold around six litres of air. But a humpback whale can hold over 1,000 litres — that’s a lot of bubbles!

You can actually see a whale’s breath: it’s a mixture of lung bacteria, hormones, proteins and lipids. It’s officially called “whale lung microbiota” — or whale snot — and looks like water droplets.

As a scientist, I use drones to sample whale snot to learn more about whale health.

We found the whales off Sydney didn’t even know their snot was being collected through this method. This is much safer for the whales and us as researchers as we don’t need to get close to each other.

Well there you have it, we’ve covered both ends of a whale. They’re incredible creatures who do enormous farts — thanks for the question!

Vanessa Pirotta, Wildlife scientist, Macquarie University

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