So that puts photosynthesis 1.7Gyr after the Earth formed. I think life is supposed to have started between 3.7 to 4.2Gyr ago, depending on which hypothesis you use - between 0.5 and 1Gy after the Earth formed. So that gives photosyntheis 0.7 to 1.2Gy in which to evolve, assuming it did (it's possible that the original version was a lot cruder than the current one, perhaps).
I like the idea that life has spread across the universe - but I also like the idea that it can evolve fairly easily. Either of these ideas - or both - make the universe a more interesting place. (Although apparently the Triffids didn't come by that route...) On 27 September 2013 06:42, Chris de Morsella <cdemorse...@yahoo.com> wrote: > Interesting bit of sci-news that seems to suggest photosynthesizing life > began oxygenating the earth's atmosphere some 700 million years earlier > than is generally believed. It also implies that it took much less time in > order for life to evolve the complex machinery of photosynthesis > (alternatively it took much longer than the now relatively short period (in > geologic time frames) that life would have had on earth to master this > complex process. An alternative explanation would be that life evolved on > some other much older star system billions of years before our sun was even > formed and has been slowly spreading -- over the eons -- throughout our > galaxy/universe ever since, preserved in the deep freeze of wandering > interstellar comets e.g. - the panspermia hypothesis. Even if viable > organisms could not survive the lengthy periods of stasis with their DNA > eventually breaking down to the point where the organisms are no longer > viable, comets could have still delivered particularly important catalysts > that are vital to the evolution of critical cellular mechanisms (such as > transcription factors for example); there are a series of these critical > catalysts that are not easy to spontaneously assemble and without which the > dynamic chemical processes necessary for life do not occur. > -Chris > > We might have to take a second look at the evolution of life on earth. > > http://www.natureworldnews.com/articles/4171/20130926/life-earth-older-previous-estimates-traces-oxygen-found-3-billion.htm > > A study on ancient soils has shown that oxygen was present on earth about > three billion years ago, pushing evolution of oxygen-breathing organisms > back in time. The study also supports the idea that life might have evolved > on other planets. > > The appearance of oxygen changed the way life evolved on Earth. Until, now > researchers believed that the Great Oxygenation Event- a dynamic period of > oxygen accumulation- occurred about 2.3 billion years back. The latest > study argues that this event might have occurred 700 million years earlier > than previously believed. > The origin of life on earth is still a matter of debate. What we do know > is that cyanobacteria- a class of bacteria that photosynthesize and release > oxygen introduced the gas to the atmosphere. > "We've always known that oxygen production by photosynthesis led to the > eventual oxygenation of the atmosphere and the evolution of aerobic life," > said Sean Crowe, co-lead author of the study and an assistant professor in > the Departments of Microbiology and Immunology, and Earth, Ocean and > Atmospheric Sciences at UBC. > We might have to take a second look at the evolution of life on earth. > life-earth-older-previous-estimates-traces-oxygen-found-3-billion > A study on ancient soils has shown that oxygen was present on earth about > three billion years ago, pushing evolution of oxygen-breathing organisms > back in time. The study also supports the idea that life might have evolved > on other planets. > The appearance of oxygen changed the way life evolved on Earth. Until, now > researchers believed that the Great Oxygenation Event- a dynamic period of > oxygen accumulation- occurred about 2.3 billion years back. The latest > study argues that this event might have occurred 700 million years earlier > than previously believed. > For the study, researchers looked at levels of chromium and other metals > in soil samples obtained from South Africa. The samples for the study were > collected from The Nsuze paleosol, an ancient soil sandwiched between > volcanic and sedimentary rocks, about 3 billion years old. Researchers also > obtained samples from Ijzermyn iron formation to compare the levels of > minerals, according to Space Reporter. > The experts looked at levels of chromium isotopes to look for traces of > oxygen. Isotopes are variants of a chemical with same number of protons, > but different number of neutrons. For example Chromium 53 (with 29 > neutrons) is heavier than chromium 52 (with 28 neutrons). > During weathering, heavier chromium 53 gets washed from rocks and is > deposited in the sea by rivers. This means that marine samples would have > higher levels of heavier chromium than terrestrial samples. In the study > too, researchers found that marine sediments had higher levels of heavier > metal isotopes, Livescience said. > "This study now suggests that the process began very early in Earth's > history, supporting a much greater antiquity for oxygen producing > photosynthesis and aerobic life," said Crowe in a news release. > According to the researchers, the study also supports the idea that life > could have evolved in other parts of the Universe. > "It's exciting that it took a relatively short time for oxygenic > photosynthesis to evolve on Earth," Crowe told Livescience. "It means that > it could happen on other planets on Earth, expanding the number of worlds > that could've developed oxygenated atmospheres and complex oxygen-breathing > life." > The study is published in the journal Nature. > > -- > 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 everything-list+unsubscr...@googlegroups.com. > To post to this group, send email to firstname.lastname@example.org. > Visit this group at http://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/groups/opt_out. > -- 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 everything-list+unsubscr...@googlegroups.com. To post to this group, send email to email@example.com. 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