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Yes, while we just have one location to go on, we do have some timing observations. Life developed about as soon as conditions allowed. Social, cooperative behavior seems to develop a lot whenever possible. (As in, a lot. There are multiple species of solitary wasps and spiders that are evolving to become social creatures right now.) Increasing intelligence is not rare, since there are several species that independently became more intelligent than any of their ancestors. (Perhaps language is a final chunk of intelligence that requires some specific brain structure that is somehow very unlikely to form.) Complex life, with Eukaryotic, multicellular creatures developed, oh, about 2 billion years after conditions allowed. A few billion years here, a few billion years there, and maybe no other planet in the galaxy has yet made it past that bottleneck. Maybe the success of multicellular animal life was founded on the fluke early development of sexual reproduction. Sexually reproducing plants came only late in the dinosaur era, after maybe half a billion years of large plant growth. What I don’t get is why eukaryotic life in particular would take so long. Cooperation is such a common development, even for microbes. https://www.nsf.gov/discoveries/disc_summ.jsp?cntn_id=129976 Separately, there might not be that many available places; while Earth-sized planets might not be rare, the really Earth-like planets might still be rare. https://blogs.scientificamerican.com/observations/our-solar-system-is-even-stranger-than-we-thought/ The mechanics of solar system development might need a combination of gas giants and Earth-sized worlds to clear out meteorites in a timely way. The level of heavy radioactive materials might not have been high enough until a few billion years ago. (You need radioactive materials to have a molten core and a magnetic field to protect from solar wind.)
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Mar 18, 2021 17:49
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| # ¿ Apr 29, 2024 03:10 |
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