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Ask Dr. Universe History and Geography
University Communications Network > Ask Dr. Universe > History and Geography

What caused the first mass extinction on Earth? – Aayush, 10, New Jersey

Dear Aayush,

It’s sad when living things go extinct. That means they’re gone forever. I think about extinct unicorns all. the. time.

My friend Jodi Rosso told me that a mass extinction is when a huge number of species die out all at once. She teaches earth science at Washington State University.

“There are periods when a whole lot of animals and plants die off in a short time,” Rosso said. “When we say a short time, we mean less than 2 million years. From a human perspective, that's forever. But in geologic time, that's short.”

Groups of living things are always expanding or shrinking their numbers. Scientists think there are as many as 10 million species on Earth right now. Between 100 and 10,000 of them go extinct every year.

A mass extinction is when big percentage of all species die off.

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Did man live with dinosaurs together? – Daniel, 9, Republic of Korea

Dear Daniel,

When I think about dinosaurs, I usually picture the big ones. I think of triceratops with its pointy horns or apatosaurus with its long, long neck.

I asked my friend John Blong if those dinos ever lived with people. He’s an environmental archeologist at Washington State University. He studies early humans.

He told me that people and dinosaurs never lived at the same time. Well, mostly.

Dinosaurs went extinct 66 million years ago when a giant asteroid crashed to Earth. It threw up tons of dust and soot. It made Earth super cold and dark. It stayed that way for a long time. The world became a very hard place to live. Eventually, 75% of all living things died, including all the big dinosaurs.

People didn’t live on Earth at that time. The only mammals that lived back then were tiny. They looked like shrews or moles. It would take millions of years before mammals adapted enough to become primates. Scientists think the first humans showed up about 300,000 years ago. That was long after the dinosaurs died out.

But some dinosaurs survived the asteroid.

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How did one comet kill all the dinosaurs? If crocodiles, snakes and birds came from dinosaurs, did it actually kill all of them? — Mya, 11.4, Virginia

Dear Mya,

It’s hard to imagine that one space rock wiped out the dinosaurs. But it did more than that. It killed 75% of the plants and animals on Earth. Me-OW.

I talked about that with my friend Barry Walker. He teaches geology classes about Earth’s history at Washington State University.

Walker told me that we call a space rock that hits Earth a meteorite. The meteorite that took out the dinosaurs set off changes on Earth. Those changes lasted for thousands of years. That’s how it killed so many things.

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Who invented the calendar? – Audrey, 9, Oregon

Dear Audrey,

I use a calendar to keep up with my work as a science cat. I also love calendar apps that count down to big events—like my birthday. People have always tracked time for work and holidays.

I talked about this with my friend Nikolaus Overtoom. He’s a professor of ancient history at Washington State University.

He told me we use the Gregorian calendar today. That's a revised version of the Julian calendar. The Romans invented the Julian calendar.

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What diseases spread on pirate ships? – Anika, 9, Georgia

Dear Anika,

A pirate’s life was dangerous. They attacked other ships and battled other pirates as well as the law. But they were also at the mercy of another foe: sickness.

I talked about this with my friend Lawrence Hatter. He’s a history professor at Washington State University.

He told me the big era for pirates was 1710 to 1730. It was a time when lots of sailors were out of work. Some of them became pirates.

Here are four kinds of disease they might face on the job: scurvy, mosquito-borne diseases, infectious diseases and gangrene.

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Are unicorns real? – Emma, 8, Minnesota

Dear Emma,

My favorite animated GIFs are the ones with cats riding unicorns. I’m delighted to tell you about a real unicorn that lived a long time ago: the Siberian unicorn.

The Siberian unicorn was bulky and furry. It had a big hump on its back. Its horn was three feet long. That’s as big as a human preschooler!

This real-life unicorn was a kind of rhino from Eurasia. But it was bigger than modern rhinos and probably galloped like a horse.

Scientists have known about Siberian unicorns since 1808. For a long time, they thought the unicorns went extinct 200,000 years ago. Recently, that changed. Now they think the unicorns went extinct closer to 39,000 years ago.

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Who invented books? – Nicole, 6, Washington

Dear Nicole,

Some people only like paper books. But I love the library app on my phone. It’s like having stacks of library books in my pocket.

To learn more about books, I talked with my friend Greg Matthews. He’s the rare books librarian at Washington State University. “The short answer would probably be the Romans,” Matthews said. “But Rome was a really vast empire. So, it could have been a Roman in North Spain. It could have been a Roman in Egypt.”

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Native American Heritage Month: What is a land acknowledgement? Why does representation matter?

WSU’s campuses are on ceded land belonging to the Nimiipuu (Nez Perce) Tribe and Palus people, traditional Cowlitz lands, traditional lands of the Confederated Tribes of the Umatilla and the Confederated Tribes and Bands of the Yakama Nation, and historical Spokane Tribe lands. This story was written on land belonging to the Confederated Tribes of Grand Ronde.

November is a great time to honor historical figures and Native American scientists changing the world right now.

I talked about this with Sara Mills, a Prevention Science graduate student at Washington State University. She’s a member of the Colville Confederated Tribes.

Mills’ research centers Native American student voices. She wants to figure out what makes those students feel like they belong.

“Representation is huge,” she said. “If you can see yourself in these spaces, then you're more willing to put yourself out there and be in those spaces. I met Native American faculty right away when I got to WSU. I don't know if I would have been able to visualize myself here if I hadn't.”

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Dr. Universe: How are coins made? -Dahlia, 10, Olympia, WA

In the United States, pennies, nickels, dimes, quarters, and other coins are made through the U.S. Mint. It turns out, they’ve been making a lot more coins than usual during the global pandemic. But more on that in a moment. It takes both science and art to make coins. Coins are made from metals that have been mixed together. We call these kinds of metals alloys. The very first coins in the world were made thousands of years ago in Turkey from electrum, an alloy of gold and silver. A penny is made from an alloy of copper and zinc. Read More ...

Why are bears called bears when they can be called anything else, not just a bear? - Natallia, 8, Yakima, Wash.

Dear Natallia,

You’ve noticed something very important: there’s no natural reason for the words humans use. Any sound could be used to describe a big mammal that eats berries and salmon.

But people who speak English choose “bear.” People who speak Spanish use “oso.” People who speak Maricopa say “maxwet.” They’re all different, but they’re all correct.

That’s what I learned from my friend Lynn Gordon, a linguist at Washington State University.

“Why do we call bears ‘bears’?” she said. “Because we’ve agreed to.”

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Dear Dr. Universe: How do people name continents or places on earth? Thank you. - Lila Grace, 8, Virginia

Our world is full of so many different places. They get their names in lots of different ways. One way a place might get a name is from the person who explored it. The Americas are named after an Italian explorer, Amerigo Vespucci. But Amerigo wasn’t the first person to explore these continents. There were already people living there when he arrived. Still, “America” was named after Amerigo. For the most part, people name things because they are claiming possession of a place. Because of that, sometimes the original names of places are lost or erased. That’s what I found out from my friend Theresa Jordan, a history professor who teaches a geography course at Washington State University. Read More ...

Dr. Universe: How did the first horse change into the horses of today? -Ava, 7, Kennewick, Wash.

We can learn a lot about animals of the past from fossils, the imprints or remains we find in rocks. One fossil found in the Bighorn Basin, Wyoming helped us learn about the oldest known horses. These horses are called Sifrhippus (siff-RIP-us). They had four toes on each foot and were very small. Believe it or not, these tiny horses weighed only about ten pounds. That’s just a bit heavier than your average house cat. According to the fossil records, Sifrhippus lived somewhere between 54 and 30 million years ago. When I went to visit my friend Lane Wallett, she told me all about the history of horses. As a veterinarian and a paleontologist at Washington State University, she is very curious about both horses and fossils. Read More ...

Dr. Universe: Why do people have different accents? Why do we have them and need them? -Florrie P., 9, UK

Whether you say hello, ‘ello, hey ya’ll, toe-may-toe or toe-ma-toe, we all have a kind of accent that often comes from where we live or who lives around us. That’s what I found out from my friend Nancy Bell, a Washington State University professor who is really curious about the way language works. She told me more about why we have accents and why we need them. There are a lot of different accents. You might have friends who speak English but have a Scottish, Irish, Australian, or French accent. Even in the U.S., there are many accents from the east to the west to the mid-west to the south. In those regions, people also speak many types of English such as Chicano English, African American English, or Indian English. Read More ...

Dr. Universe: Back when cell phones weren’t a thing, how could you place a call from across the ocean? Were there wires under the ocean? -Tali, 9, Seattle, Wash.

Long before telephones, if you wanted to say “hi” to friend across the ocean you’d probably write them a letter and send it over on a ship. But in the last hundred years or so, we’ve been able to connect across the ocean much faster. And yes, it often required thousands of miles of wires, or cables, deep in the sea. That’s what I found out from my friend Bob Olsen, a professor of electrical engineering at Washington State University, who told me all about the telephone. Read More ...

Dr. Universe: How do earthquakes happen? -Aescli E., 10, Utah

We’ve had a lot of earthquakes on our planet this year. Maybe you’ve learned about them from the news or felt one shaking up your own neighborhood. First, it is important to know a bit about the Earth’s outer layer, or crust. The crust is made of seven big pieces called “plates.” They are about 60 miles thick and sort of float on the molten rock beneath them. That’s what I found out from my friend Sean Long, a geology professor at Washington State University who knows a lot about earthquakes. Read More ...

Why do we have different feelings? - Charan and Aishwarya V., 10 & 8, Rutherford, New Jersey

Dear Charan and Aishwarya,

Imagine you are playing a game of soccer and your best friend is on the opposing team. The sun is out, you are having a great time, and you score the winning goal. You’d probably feel pretty happy and so would your team.

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Why is Pi 3.1415...? What if it was just 3? -anonymous

Dear Curious Readers,

It’s almost March 14. You know what that means: Pi Day, as in 3/14, or 3.14159265359 and so on.

I met up with my friend Nathan Hamlin, a mathematician and instructor here at Washington State University, to explore your question about this never-ending number.

We calculated Pi with some of my favorite items: yarn and a tuna can. You can try it at home, too.

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Why is yawning contagious? -Grant, 10, Pullman, WA

Dear Grant,

When I got your question, I met up with my friend Hans Van Dongen, a scientist at Washington State University in Spokane. He works in a research lab where they study sleep. As a cat who appreciates naps, it’s one of my favorite places to visit.

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If mollusks have such heavy shells to drag around with them, how have they spread all over the ocean? -Michel W.

Dear Michel,

Mollusks, from land snails and slugs to oysters and mussels in the sea, have a few things in common. They have a head. They have a soft middle part that holds their organs. Then, some have a muscle that’s known as a “foot.”

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Dr. Universe, How are magnets made? -Andrea, 8, Berkeley, CA 

                                                                                   

Dear Andrea,

When I saw your question, I headed straight for the Magnetics Lab and met up with my friend John McCloy. I found out the word “magnet” comes from a Greek word for the region of modern-day Turkey we once called Magnesia. That’s where people found magnets in nature.

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