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 <[email protected]> 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 [email protected]. > To post to this group, send email to [email protected]. > 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 [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/everything-list. 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