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Ask Dr. Universe primates

Why do we have fingerprints? – Kaylen, 11, North Carolina

Dear Kaylen,

I use my paws for all kinds of things. That’s how I adjust my microscope, set up my microphone for a podcast and write answers to science questions. But most cats don’t do those things. Maybe that’s why cats don’t have fingerprints like yours.

I asked my friend Katherine Corn about that. She’s an evolutionary functional morphologist. She studies how animal bodies evolved to do all kinds of jobs. She’s the director of Washington State University’s museum of vertebrate zoology.

Metal shelves holding many glass bottles filled with vertebrate specimens» More …

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Did dinosaurs eat humans? – Brileigh, 10, North Carolina

Dear Brileigh,

If you looked inside a T. rex mouth, you’d see some 12-inch teeth. That’s longer than my tail!

I asked my friend Aaron Blackwell if dinosaurs used those big chompers on humans. He’s an anthropologist who studies human biology at Washington State University. He told me dinosaurs and humans didn’t live at the same time.

“Dinosaurs died out 65 million years ago—before there were even primates,” Blackwell said. “So, they could never have eaten a human or even a monkey.”

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Dr. Universe: Why do we have toenails and fingernails? – Chloe, 12, Texas

Dear Chloe, Maybe you like to paint your toenails beautiful colors or admire the dirt under your fingernails when you come in from playing outside. But you’re right to notice that nails must be more than just decoration. To learn more, I talked to my friend Edward Johnson, an assistant professor of anatomy and physiology at Washington State University. Johnson reminded me that humans are primates, just like gorillas or orangutans. If you look closely at a primate’s hand or foot, you’ll see their nails look a lot like yours. They’re wide and flat at the ends of their fingers and toes. Read More ...