Bad Eyesight
Why didn't humans adapt to have good eyesight? (Eye adjusts to keep things in focus, but sometimes …
Why Is It?
Spitballs
What does spit do for a baseball pitcher's spitball? (makes the ball slippery so it doesn't spin)
Contagious Yawning
Why are yawns contagious? (They signal a change in state, so our brain detects them.)
Salty Ocean
How did the ocean get salty? (from rocks on land that get dissolved by rain and washed into the sea)
Cats and Barking
How come cats don't bark? (Barking is meaningless, and cats have a clear set of vocal signals.)
No-Cal Sugar
How can sucralose be made of sugar and not have any calories? (Tongue recognizes it, but not …
Mosquito Bites
How does a mosquito know that it's biting a human? (Senses carbon dioxide and other chemicals)
Coastal Hurricanes
Why aren't there hurricanes on the West Coast? (Water isn't warm enough to sustain them.)
Eye Size
Does the eye get bigger as we get older? (yes, but it's already 65 percent of adult size at birth)