A research team of Specially Appointed Associate Professor Harrison B. Smith of Earth-Life Science Institute (ELSI) at Institute of Science Tokyo and Specially Appointed Associate Professor Lana Sinapayen of National Institute for Basic Biology has developed a new approach to detecting life beyond Earth that does not rely on identifying specific biological markers. Instead, the study suggests that life may be detectable through patterns emerging across groups of planets, offering a new framework for astrobiology in situations where traditional biosignatures are ambiguous or unreliable.
One of the main challenges in astrobiology is establishing whether observed features of distant planets genuinely indicate the presence of life. Traditional biosignatures, such as atmospheric gases, can often produce false positives through non-biological processes. Although technosignatures might offer more reliable signals, they rely heavily on strong assumptions about the nature and behaviour of extraterrestrial intelligence.
To overcome these limitations, the researchers considered a fundamentally different idea: instead of searching for life on individual planets, what if life could be detected through its collective effects across many planets?
The study presents an "agnostic biosignature"—a method that does not rely on knowing in detail what life consists of or how it functions. Instead, it is based on two broad assumptions: that life can spread between planets (for example, through panspermia), and that it can modify planetary environments over time.
Using an agent-based simulation, the researchers modelled how life might spread across star systems and alter planetary characteristics. They discovered that if life extends and impacts planetary environments, it produces detectable statistical correlations between planet locations and their observable traits.
Crucially, these correlations appear even without pinpointing a particular biosignature on any individual planet.
Beyond detecting the presence of life, the researchers also developed a method to identify which planets are most likely to host it. By clustering planets based on their observable characteristics and spatial relationships, they were able to isolate groups of planets with a high probability of having been influenced by life.
This approach prioritises reliability over completeness: it minimises false positives, even if it misses some life-bearing planets. Such a strategy is especially useful for guiding follow-up observations with limited telescope time.
"By focusing on how life spreads and interacts with environments, we can search for it without needing a perfect definition or a single definitive signal," said Harrison B. Smith. Lana Sinapayen added, "Even if life elsewhere is fundamentally different from life on Earth, its large-scale effects, such as spreading and modifying planets, may still leave detectable traces. That's what makes this approach compelling."
The findings indicate that future astronomical surveys, which will observe large numbers of exoplanets, could employ statistical methods to detect life on a population level. This approach might be especially useful when individual biosignatures are faint, ambiguous, or susceptible to false positives.
The study also highlights the importance of better understanding the baseline diversity of planets formed without life, as this will improve the reliability of detecting deviations caused by biological processes.
While the current work relies on simulations, it provides a conceptual basis for a new category of life-detection methods. The researchers emphasise that future efforts must incorporate more realistic planetary data and galactic dynamics. Nevertheless, the results suggest that life could be detectable even without understanding its chemistry, by recognising the patterns it leaves throughout the cosmos.
Reference
Harrison B. Smith 1, 2, ∗ and Lana Sinapayen 3, 4, † , An Agnostic Biosignature Based on Modeling Panspermia and Terraforming, The Astrophysical Journal , DOI: 10.3847/1538-4357/ae4ee3
Contacts:
Thilina Heenatigala
Director of Communications
Earth-Life Science Institute (ELSI),
Institute of Science Tokyo
E-mail: thilinah@elsi.jp
Tel: +81-3-5734-3163
Harrison B. Smith
Specially Appointed Associate Professor
Earth-Life Science Institute (ELSI),
Institute of Science Tokyo
E-mail: hbs@elsi.jp
More information
Earth-Life Science Institute (ELSI) is one of Japan's ambitious World Premiere International research centers, whose aim is to achieve progress in broadly inter-disciplinary scientific areas by inspiring the world's greatest minds to come to Japan and collaborate on the most challenging scientific problems. ELSI's primary aim is to address the origin and co-evolution of the Earth and life.
Institute of Science Tokyo (Science Tokyo) was established on October 1, 2024, following the merger between Tokyo Medical and Dental University (TMDU) and Tokyo Institute of Technology (Tokyo Tech), with the mission of "Advancing science and human wellbeing to create value for and with society."
World Premier International Research Center Initiative (WPI) was launched in 2007 by Japan's Ministry of Education, Culture, Sports, Science and Technology (MEXT) to foster globally visible research centers boasting the highest standards and outstanding research environments. Numbering more than a dozen and operating at institutions throughout the country, these centers are given a high degree of autonomy, allowing them to engage in innovative modes of management and research. The program is administered by the Japan Society for the Promotion of Science (JSPS).
The National Institute for Basic Biology (NIBB) was founded in 1977 to promote and stimulate studies in the field of biology. As a center of excellence (COE), NIBB promotes biological sciences by conducting first-rate research on its own as well as in cooperation with other universities and research organisations. Research at NIBB covers a wide variety of biological fields, such as cell biology, developmental biology, neurobiology, evolutionary biology, environmental biology, and theoretical biology, and is conducted to elucidate general and fundamental mechanisms underlying various biological phenomena.
The Astrophysical Journal
Computational simulation/modeling
Not applicable
An Agnostic Biosignature Based on Modeling Panspermia and Terraforming
9-Apr-2026