SETI: Rethinking the Search for Alien 'Footprints'

Any intelligent extraterrestrial life that exists probably won't announce itself by blowing up the White House, or win over the hearts of children as a lovable alien with a glowing finger.

Many scientists simply hope to find evidence of them by scanning the skies for a radio signal from a distant star's alien civilization but such efforts may also risk overlooking clues of past alien activity right here on Earth.

If aliens did leave their mark on Earth by some wild chance, we could search for the possible "footprints" of alien technology or even analyze the DNA of terrestrial organisms for signs of intelligent messages or tinkering.

Such a CSI-style forensics search could complement, rather than replace, the Search for Extra-Terrestrial Intelligence (SETI) astronomers who continue to look skyward, said Paul Davies, a physicist and cosmologist at Arizona State University in Tempe, Ariz.

"My proposals aim to spread the burden from a small band of heroic radio astronomers to the entire scientific community," Davies said. "Projects like genomic SETI are an attempt to complement radio SETI, not undermine it."