Many researchers [envision] ย five: 1) the creation of single-celled life (“abiogenesis”), 2) the appearance of photosynthesis that creates oxygen, 3) the emergence of eukaryotic cells from prokaryotic cells, 4) the emergence of complex life, such as multicellular animals, and 5) the rise of Homo sapiens with an established language.
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So the question arises if intelligent, technological animals like us developed on Earth only late in the time available, [that’s] cutting it close. Would the same fate befall any advanced extraterrestrial life elsewhere in the galaxy? Might they have developed too late in their sun’s timespan to get to Earth? The hard steps model thus predicts that technological species such as humans on Earth are exceedingly rare in the universe.





















