Biosignature Potential of TOI-700 d within the Framework of Cosmic Inevitability and the Detection of Exoplanetary Biospheres in the Age of Artificial Intelligence

The search for life beyond the Solar System has long been influenced by two major tendencies: the habit of seeking life strictly modeled after Earth’s biology, and an observational bias toward easily detectable targets. In this study, I first examine the dimethyl sulfide (DMS) signal reported in the atmosphere of K2-18 b. I discuss how the 2023 observational signal remained statistically marginal, overlaps with methane absorption features, and how the planet is far more likely to be a gas-rich mini-Neptune rather than an ocean-bearing "Hycean" world. Next, I analyze TOI-700 d, located in the habitable zone of a quiet M2V red dwarf. With a radius of approximately 1.14 Earth radii, an insolation flux of ~0.86 of Earth's, and an absence of notable flare activity in TESS photometric data, TOI-700 d emerges as a substantially more stable and viable candidate. The central hypothesis I advocate is that on planets capable of sustaining favorable conditions over astronomical timescales—chiefly Earth and TOI-700 d—the emergence of life, at least at the microbial level, is virtually inevitable. Finally, considering the exponential acceleration of technology and the advancement of AI-driven observational methods, I predict that a compelling biosignature candidate will be confirmed on TOI-700 d or an analogous rocky world by 2033 at the latest. I base this prediction on the premise that self-improving artificial intelligence will drastically accelerate the design and deployment of novel observation technologies. I anticipate that government regulations over the next two years may temporarily decelerate this pace, but will not halt the trajectory.