On Saturday, March 7, 2020 at 10:51:07 AM UTC-6, John Clark wrote: > > On Sat, Mar 7, 2020 at 7:54 AM Lawrence Crowell <[email protected] > <javascript:>> wrote: > > > The occurrence of life on Earth in such a rapid time does pose a >> possibility for a fairly rapid occurrence, at least on a geological time >> scale. for life. > > > Life needs water and liquid water has existed on the Earth for 4.4 billion > years. > > Evidence from zircons for the existence of oceans on the Earth 4.4 Gyr ago > <http://www.geology.wisc.edu/~valley/zircons/Wilde2001Nature.pdf> > > Even though it had liquid water there is no evidence life existed on Earth > until 900 million years had passed, and even then it was just bacteria. It > took another 800 million years before the first eukaryotes evolved, and 2 > billion years after that before the first multicellular creatures evolved, > and 700 million years after that before creatures with the ability to make > radio telescopes evolved. That doesn't seem very rapid to me, the sun will > start to turn into a red giant in about 500 million years, so if the > process had been a bit slower we'd be going extinct along with everything > else on the planet when we had achieved about the same level of technology > that we have now. > > John K Clark >
Biology appeared on Earth about 3.7 billion years ago. It is thought life may have originated around thermal vents in the early ocean, which could push the emergence of life back to 4 billion years. This means that after the so called Hadean period of mass bombardment life emerged within a few 100 million years. Given that time periods tend to telescope the early you go in geological history this is fairly quick. LC -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/2ea7209d-69c9-479f-94a2-03ffb6fad81f%40googlegroups.com.
