Scientists looking for extraterrestrial life have a problem: They can find the molecular fingerprints of biology everywhere. The problem is that fingerprints themselves are not unique. Life-building components such as amino acids, proteins and fatty acids can be created in non-living systems in exactly the same way that they can be created by living things.
The presence of phosphine in Venus’ atmosphere could indicate bacteria or sulfuric acid reactions. The detection of dimethyl sulfide in the atmosphere of exoplanet K2-18b raised some hopes, followed by doubts.
Fingerprint detection is not the same as detection of life itself. It implies the detection of a print that someone could have left there.
In recent studies conducted by scientists including Gideon Yoffe of the Weizmann Institute and Fabian Klenner of the University of California, Riverside, there may now be a new technique to detect deeper fingerprints in the search for life elsewhere.
Yoffe and Klenner adopted the idea from ecology, where life on Earth is evaluated based on diversity and abundance. But their method uses this concept for molecules.
The research team analyzed data from about 100 samples of asteroids, fossils, meteorites, microbes, soil and synthetic materials in the laboratory to investigate how different amino acids and fatty acids are organized in biological and abiotic processes.
Amino acids produced by organisms were more diverse and evenly distributed throughout a sample than those produced abiotically. Fatty acids showed the opposite; they were less diverse and less evenly distributed when they were created by life.
“Our approach could make the search for life more efficient,” Klenner said Space.com. “If a molecular assembly does not show lifelike organization, this can make it a lower priority target.”
Neither pattern alone proves that life exists, but the signature of the organization tells you something important: this wasn’t a random chemical activity.
