H.G. Wells might not have been that far off when he wrote about aliens from Mars coming to Earth.
"It may not be likely," NASA researcher David Morrison told National Geographic News, "but we cannot exclude the possibility that we are, in effect, all Martians."
Panspermia, or the idea that Earth was "seeded" by life from outer space, is centuries old but until lately has not had much scientific evidence to support it.
But a European experiment last month demonstrates that microscopic life could indeed survive inside rocks hurtling through space.
A team led by John Parnell from the University of Aberdeen in Scotland embedded fossilized microbes into a fake meteorite strapped to the exterior of the Russian Foton M3 scientific-research probe, which went into orbit on Sept. 26 and came back to Earth 12 days later.
"In the bit of rock we got back, some biological compounds have survived," Parnell told National Geographic News.
The large number of rocks from Mars that end up on Earth lends credence to the hypothesis that terrestrial life may have had its origin on the Red Planet, which 4 billion years ago was much more hospitable than Earth was at the same time.
Click here to read the story at National Geographic News.