A proposed new method for detecting life beyond Earth could transform the search for extraterrestrials, even if those lifeforms follow completely different biochemistry to our own.
Researchers from the Earth-Life Science Institute, Tokyo and the National Institute for Basic Biology in Okazaki have built on the idea of ‘agnostic’ biosignatures – ways of identifying life based on large-scale patterns across multiple planets, rather than on specific chemical markers.
Traditional approaches detect biosignatures like oxygen or methane in a planet’s atmosphere, gases associated with life on Earth.
But these rely heavily on Earth-based assumptions and may fail to detect unfamiliar forms of biology.
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The new research instead starts from the idea that if life of any type is spreading between planets – whether through technology like rockets or by panspermia, carried on meteors or cosmic dust – it could gradually make those worlds more alike than would be expected by chance.
Using statistical tests applied to simulated planet populations, the study argues that this similarity wouldn’t require deliberate terraforming, but could arise simply from life changing planetary atmospheres.
"By focusing on how life spreads and interacts with environments, we can search for it without needing a perfect definition or a single definitive signal," says lead author Harrison Smith.
Co-author Lana Sinapayen adds: "Even if life elsewhere is fundamentally different from life on Earth, its large-scale effects, such as spreading and modifying planets, may still leave detectable traces."
The method could redefine one of science’s most profound questions: how to recognise life in a Universe where it may take forms we can’t even imagine.
