What causes a runny nose? Spicy foods, cold weather, and—strangely—crying. Here’s why.
Do you know the saying “what goes up, must come down”? Here is why we don't fall off the Earth.
Chemicals from special glands on a dog's rear end tell other dogs a lot about them. Here's why dogs sniff each other's butts.
Parrots can learn how to say hundreds of words—and even know what some of them mean.
It all comes down to vocal cords and hormones. Here's why girls' voices are usually higher than boys' voices.