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Dr. Universe: What gives leaves their shapes? Please reply back. Thanks a ton! -Pronoy, 9, San Jose, CA, USA

We can find all kinds of leaves on our planet. Just think of tiny pine needles, fern fronds, ivy vines, or a big banana leaf. My friend Eric Roalson is a professor at Washington State University who is very curious about plants. He said there are a few things that give leaves their shapes. The shape of a leaf can depend on the family history of a plant, the group it belongs to, and the environment where it grows up. Read More ...

Dr. Universe: Why do we have spines? - Jessie, 10, Covina, Calif.

Dear Jessie,

Your spine is more than just a long line of bones. It’s the secret to jumping for joy, the base for all your best dance moves. Every time you run, climb, walk, and play, your spine is right there with you.

“Without a spine, our ability to move would be completely different,” Edward Johnson said.  Johnson teaches Human Anatomy in the School of Biological Sciences at Washington State University. He is very curious about how all the parts of your body work together.

All creatures with spines are called “vertebrates,” including humans. They get this name from their vertebrae: the special bones that make up the spine. Your vertebrae are different shapes and sizes, but they all connect together.

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How are seashells formed? And why are they different colors? Can seashells live or die? - Caroline, 9, Crestwood, Ky.

Dear Caroline,

Seashells come in an astounding variety. Some are curved and round, others long and tube-like. Some are smooth, others bumpy. Some are large, others small. Plus, they come in a rainbow of colors: red, green, brown, purple, pink, and more.

All that variety comes from the same source: little animals called mollusks, with a mighty muscle called a mantle.

I found out all about them from my friend Richelle Tanner, a scientist at Washington State University. She is very curious about the ocean and knows a lot about mollusks, a type of animal with a soft, moist body.

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Dr. Universe: Why do people have different fingerprints? - Mary, 12, South Carolina

Dear Mary,

Did you know even identical twins have different fingerprints? It can be hard to tell twins apart, but a close look at their fingertips can reveal who’s who. The reason lies partly in their genes, but mostly from the unique way everyone’s skin grows before birth.

That’s what I learned from my friend David M. Conley, a professor at Washington State University’s Elson S. Floyd College of Medicine.

“The reason fingerprints are unique is the same reason individual humans are unique,” Conley said. “Variation is the norm, not the exception.”

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Dr. Universe: Why are brains mushy? – First Graders, Waller Road Elementary, Puyallup, Wash.

Dear First Graders,

You’re right, brains are quite mushy. It turns out the three-pound organ between your ears is mostly made up of water and fat.

I found out all about brains from my friend Jim Peters, a neuroscientist at Washington State University.

“It’s gooey. It really is squishy,” he said. “When it is warm, it is kind of like butter.”

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Dr. Universe: Why do we have a tailbone? -Tyler, 15, East Liverpool, England

Dear Tyler,

At the very bottom of the human spine is a bone that sticks out a bit called the coccyx (cox-ix). We sometimes call it the “tailbone,” but it is actually made up of several different spinal bones.

In some animals that actually have tails, those different bones at the bottom of the spine help them move their tail around. But in humans, those bones partially fused together.

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Dear Dr. Universe: How do we talk? – Emmy, 7, Wash. State

Dear Emmy, When you were a little kid, maybe you played Peek-a-Boo or sang “Itsy Bitsy Spider.” These kinds of games and songs have a lot of the different sounds we make when we are first developing speech. A lot of humans start out playing with speech through cooing and crying. At about six months old, this cooing and crying turns to babbling. A baby might make sounds such as ma-ma, pa-pa, or ba-ba. Read More ...