Scientist: Alien life could already be on Earth

LONDON (AP) - For the past 50 years, scientists have scoured the skies for radio signals from beyond our planet, hoping for some sign of extraterrestrial life. But one physicist says there's no reason alien life couldn't already be lurking among us—or maybe even in us. 

Paul Davies, an award-winning Arizona State University physicist known for his popular science writing said Tuesday that life may have developed on Earth not once but several times.

Davies said the variant life forms—most likely tiny microbes—could still be hanging around "right under our noses—or even in our noses."

"How do we know all life on Earth descended from a single origin?" he told a conference at London's prestigious Royal Society, which serves as Britain's academy of sciences. "We've just scratched the surface of the microbial world." (Read more)