Extraterrestrial life could betray itself not in the molecules themselves, but in their arrangement. A recent study shows that living systems leave distinctive statistical patterns in their organic compounds, invisible at first glance. These patterns differ radically from those produced by non-biological chemistry, offering a new avenue for spotting extraterrestrial biological activity.
To this end, researchers from the University of California, Riverside and the Weizmann Institute analyzed hundreds of samples, from microbes to meteorites. Their finding is clear: life imprints a particular organization on molecules, which can be highlighted by simple statistical tools. This signature could be detected by current space missions, without the need for additional instruments.
The search for extraterrestrial life could benefit from an approach that looks beyond a simple biosignature.
Credit: NYU Abu Dhabi Among the main discoveries, amino acids of biological origin prove to be more diverse and more evenly distributed than those created by abiotic processes. Fatty acids, on the other hand, follow the opposite trend. These differences are systematic and allow a living sample to be distinguished from an inert one with high reliability.
Molecules associated with life, such as amino acids, can form in space without the intervention of living organisms. They are found in meteorites and reproduced in the lab. Finding these molecules is therefore not enough. But the new method makes it possible to decide by examining their overall organization, a criterion that only life seems to produce.
To achieve this, the researchers borrowed concepts from ecology: richness (number of types of molecules) and evenness (balanced distribution). These indicators, used to measure biodiversity, proved perfectly suited to chemical analysis. The results were surprising in their consistency, even on highly degraded samples such as fossilized dinosaur eggshells.
The approach has a major advantage: it can be applied to data already collected by missions such as those exploring Mars, Europa, or Enceladus. Scientists do not need to design new detectors; it is enough to apply statistical algorithms to existing measurements. This significantly accelerates the search process.
The authors of the study caution that no single technique can alone prove the existence of extraterrestrial life. But this statistical approach, combined with other geological and chemical clues, greatly strengthens the reliability of detections. The future of space missions may well include this new tool in their arsenal.