Scientists searching for extraterrestrial life face a problem: They can find molecular fingerprints of biology everywhere. The point is that fingerprints themselves are not unique. Life-building components such as amino acids, proteins, and fatty acids can be made in nonliving systems just as they can be made by living things.
The presence of phosphine in Venus’s atmosphere may point to either bacterial or sulfuric acid reactions. The detection of dimethyl sulfide in the atmosphere of exoplanet K2-18b sparked some hope, followed by skepticism.
Detecting fingerprints is not equivalent to detecting life. This means finding prints that anyone could have left there.
Recent studies by scientists including Gideon Yoffe of the Weizmann Institute and Fabian Kleiner of the University of California, Riverside, may now have a new technique for detecting deep fingerprint signatures in the search for life elsewhere.
Yoffe and Kleiner adopted this idea from ecology, where life on Earth is evaluated in terms of diversity and abundance. But his method uses this concept for molecules.
The research team analyzed data from nearly 100 samples of asteroids, fossils, meteorites, microbes, soil and synthetic materials in the laboratory to investigate how different amino and fatty acids organize in biological and abiotic processes.
Amino acids produced by organisms were more diverse and more evenly distributed across a sample than nonbiologically made amino acids. Fatty acids showed the opposite; They were less diverse and less evenly distributed when life formed.
“Our approach could help make the search for life more efficient,” Kleiner said. space.com. “If a molecular combination shows no life-like organization, this may make it a low-priority target.”
No single pattern alone proves that life exists, but organizational signatures tell you something important: This was not random chemical activity.
