Courtesy of the folks at LiveScience.com
A chicken can live without its head: True - and not just for a few minutes. A chicken can stagger around without its noggin because the brain stem, often left partially intact after a beheading, controls most of its reflexes. One robust fellow lives a full 18 months! (Not sure I believe that, but growing up on a farm, I have seen them run around for a while.)
Water drains backward in the Southern Hemisphere due to the Earth's rotation: False - Not only is the Earth's rotation too weak to affect the direction of water flowing in a drain, tests you can perform yourself in restrooms will prove that water whirlpools flows both ways depending ont he sink's structure, not the hemisphere. (Boy, and I thought I had learned this lie from The X-Files.)
Humans use only 10% of their brains: False. This myth has been around for at least a century. MRI imaging clearly demonstrates, in technicolor, that humans put most of their cerebral cortex to good use, even while dozing.
Eating a poppy-seed bagel mimics opium use: True. Tests suggest ingesting just two poppy seed bagels may produce a positive result for opiates on a drug screen. (I work in a lab - I know it's true!)
A penny dropped from a tall building could kill a person: False - a penny isn't the most aerodynamic of weapons. A combination of its shape and wind friction means that, tossed even from the 1,250-foot Empire State Buildin, it would travel fast enough to merely sting an unlucky pedestrian.
Adults don't grow new brain cells: False. Much of the human's crucial brain development happens during childhood, but it isn't all downhill from there. Studies have shown that neurons continue to grow and change well into the adult years. (So there's hope for me yet!)
Yawning is contagious: Empirically, this is tough to deny. The real question is whether there's actually something physiological at work here, and the answer is likely "yes": Even chimpanzees mimic each other's yawns. (I hope you're not yawning reading this!)
A falling cat will always land on its feet: True - studies have demonstrated that, when dropped from most heights, cats will land gracefully on their feet. Results change only whit cats dropped upside-down from 1 foot or less. (Do not try this at home!)
The Great Wall of China is the only man-made structure visible from space: False - Astronauts can spot the Great Wall from low Earht orbit, along with other things like the Giza pyramids and even airport runways. But they can't see the Wall from the Moon.