Last Universal Common Ancestor (LUCA)
Hypothetical most recent population of organisms from which all currently living organisms on Earth descend; conventionally dated ~4.2 billion years ago.
Per src-loeb-panspermia-impact-survival-2026-03, avi-loeb argues LUCA may have been delivered to Earth from Mars via panspermia — Mars cooled to habitable conditions before Earth, alh84001 demonstrates the transit thermal-survival window, and the new ~2 GPa impact-survival evidence underwrites the spallation-ejection step. Loeb summarizes: “It is possible that we are all Martians.”