Life's Little Mysteries: Science questions, answered

Although many researchers assume that birthday celebrations date back to the ancient Egyptians, the earliest textual evidence of a birthday party proves these annual events are much older.

Animals hear other species communicate around them every day. Do they understand what they're saying?

People go on 5K and 10K runs all the time. But what's the farthest humans can run at one time?

Kissing is a multifaceted and emotionally loaded behavior. Do other animals do it, too?

Nuclear bunkers aren't a foolproof way to stay safe during a nuclear attack. Here's why.

Flies are attracted to our pungent "cloud of effervescence," experts say.

How do Hula-Hoops keep from falling down as we twirl them around?

If you're wondering whether birds are reptiles, know this: The reptile family tree is more varied and diverse than you might realize.

Photokeratitis, or eye sunburn, can happen at any time of the year.

Alexander the Great died at age 32, but his cause of death is unclear. What killed him has been a long-standing source of debate.