1. Why don't monkeys have whiskers?
2. Why is it impossible to effectively tickle oneself, and what makes some people more ticklish than others?
3. How do people get sleep in their eyes, and where does it come from?
4. How do scientists know which animals see in color and which see just black and white?
5. How is it that when people draw "hearts", that shape isn't at all what a heart looks like, and who invented that shape?