Researchers find new method for detecting life

How can life be detected? Certain molecules alone provide at best a hint. But amino acids are found on asteroids, and fatty acids can also be formed through non-biological processes. Therefore, they cannot serve as proof. A team of researchers from Israel and the USA believes it is the order of the molecules.

The team led by Gideon Yoffe from the Weizmann Institute of Science in Rehovot, Israel, has found that amino acids in a sample originating from a living organism are more diverse and evenly distributed than in abiotic or non-living materials. The opposite is true for fatty acids: abiotically produced fatty acids are more evenly distributed than those produced by biological processes.

For the study published in Nature Astronomy, the researchers analyzed around 100 existing datasets with amino acids and fatty acids from microbes, soils, fossils, meteorites, asteroids, and synthetic laboratory samples. This revealed clear organizational patterns that distinguished biological samples from those of non-living chemistry.

Life creates a principle of order

“We’re showing that life does not only produce molecules,” said co-author Fabian Klenner from the University of California, Riverside (UC Riverside). “Life also produces an organizational principle that we can see by applying statistics.”

Although the method is quite simple, it proved to be very powerful: it reliably distinguished between biological and non-biological samples. The principle was still recognizable even in heavily decomposed samples: even fossilized shells of dinosaur eggs still carried the statistical signatures of ancient life within them.

According to the researchers, the advantage is that this statistical approach for detecting life does not rely on a specific instrument. This means that the method can also be applied to data collected by instruments on planned space missions, for example, to Mars, Jupiter's moon Europa, or Saturn's moon Enceladus.

Ultimately, however, no single method will be sufficient to prove the existence of extraterrestrial life. “Any future claim of having found life will require multiple independent lines of evidence that must be interpreted in the geological and chemical context of a planetary environment,” Klenner said. “Our approach provides another way to assess whether life might have existed there. If different methods all point in the same direction, then that is very convincing.”

(wpl)