Researchers have achieved a significant breakthrough in astrobiology by unveiling a straightforward and dependable method’s for detecting indications of past or current life on other planets
In a paper published in the journal Proceedings of the National Academy of Sciences, a team of seven researchers, supported by the John Templeton Foundation and led by Jim Cleaves and Robert Hazen from the Carnegie Institution for Science, reveals that their AI-driven approach can effectively tell apart modern and ancient biological samples from non-living ones with an accuracy rate of 90%.
“This routine analytical method has the potential to revolutionise the search for extraterrestrial life and deepen our understanding of both the origin and chemistry of the earliest life on Earth,” says Dr. Hazen.
Planetary exploration: Finding life on other planets?
This test has immediate applications in uncovering the origins of enigmatic ancient Earth rocks and potentially shedding light on samples gathered by the Mars Curiosity rover’s onboard analytical tool known as SAM, Sample Analysis at Mars.
“We’ll need to tweak our method to match SAM’s protocols, but it’s possible that we already have data in hand to determine if there are molecules on Mars from an organic Martian biosphere.”
“The search for extraterrestrial life remains one of the most tantalising endeavours in modern science,” says lead author Jim Cleaves of the Earth and Planets Laboratory, Carnegie Institution for Science, Washington, DC.
AI-Powered molecular analysis
This analytical approach doesn’t depend solely on pinpointing individual molecules or compound groups in a sample. Instead, it showcases how AI can distinguish between living and non-living samples by identifying subtle distinctions in the molecular patterns of a sample. This is achieved through pyrolysis gas chromatography analysis, which separates and identifies a sample’s components, followed by mass spectrometry to determine the molecular weights of these components.
AI was trained using extensive multidimensional data obtained from the molecular analysis of 134 known carbon-rich samples, both living and non-living. It achieved an accuracy rate of approximately 90% in identifying the origin of new samples. These origins included:
- Living organisms like shells, teeth, bones, insects, leaves, rice, human hair, and cells preserved in fine-grained rock.
- Traces of ancient life transformed by geological processes, such as coal, oil, amber, and carbon-rich fossils.
- Samples with non-living origins, such as pure laboratory chemicals (e.g., amino acids) and carbon-rich meteorites.
Ancient origins
Previously, tracing the origins of ancient carbon-rich samples was challenging because of organic molecules, whether from living or non-living sources, tend to break down over time. However, the new method surprisingly detected evidence of biological traces preserved for hundreds of millions of years despite substantial degradation and changes.
Says Dr. Hazen: “These results mean that we may be able to find a life form from another planet, another biosphere, even if it is very different from the life we know on Earth. And, if we do find signs of life elsewhere, we can tell if life on Earth and other planets derived from a common or different origin.”
Co-author Anirudh Prabhu from the Carnegie Institution for Science describes the AI’s function similar to categorising coins by various characteristics, such as their monetary value, metal composition, year of minting, weight, or size.
Additionally, the AI delves deeper by identifying combinations of these attributes that lead to more refined distinctions and groupings. “And when hundreds of such attributes are involved, AI algorithms are invaluable to collate the information and create highly nuanced insights.”
This method can address several scientific enigmas on Earth, such as clarifying the source of 3.5 billion-year-old dark sediments in Western Australia. These rocks have sparked intense debates, with some scientists asserting they contain Earth’s oldest fossilised microbes, while others argue they lack any signs of life. Similar disputes surround samples from ancient rocks in Northern Canada, South Africa, and China.
This innovative approach has sparked fresh concepts regarding its potential applications in other domains, including biology, palaeontology, and archaeology.
