Summary

Common descent theory plays an influential role in shaping the search for extraterrestrial life by providing insights into evolutionary processes, universal biology, and potential biosignatures. Although it offers valuable guidance for identifying environments and characteristics favorable to life beyond Earth, scientists must remain open to discovering organisms fundamentally different from those known on our planet. Balancing expectations informed by Earth’s biology with the readiness to encounter unprecedented forms of life is essential for advancing the search for extraterrestrial organisms.