Nell Greenfieldboyce

Why people yawn is a mystery. But yawning starts in the womb.

Past studies have used ultrasound images to show fetuses yawning, but some scientists have argued that real yawns were getting confused with fetuses simply opening their mouths.

So Nadja Reissland, a researcher at the University of Durham in the United Kingdom, used a more detailed ultrasound technique to get images of fetal faces that could distinguish a true yawn from just an open mouth.

Scientists say an Asian elephant at a South Korean zoo can imitate human speech, saying five Korean words that are readily understood by people who speak the language.

The male elephant, named Koshik, invented an unusual method of sound production that involves putting his trunk in his mouth and manipulating his vocal tract.

"This is not the kind of sound that Asian elephants normally make, and it's a dead-on match of the speech of his trainers," says Tecumseh Fitch of the University of Vienna in Austria.

Here's your chance to weigh in on mutant forms of bird flu that have been in the news — the U.S. government wants to know just how scary you think these new viruses are.

Two Americans have won the 2012 Nobel Prize in Chemistry. Robert Lefkowitz and Brian Koblika were awarded the prize for their work on protein receptors that tell cells what's going on around the human body. Their research has allowed drug makers to develop medication with fewer side effects. The pair with share the $1.2 million award.

Americans Robert Lefkowitz and Brian Kobilka have won the 2012 Nobel Prize in chemistry. The Royal Swedish Academy of Sciences cited the two researchers Wednesday "for studies of G-protein-coupled receptors."