Today , oxygen take a crap up about21 % of our atmosphere , but it was n’t always so plentiful . Around 2.7 billion years ago , cyanobacteria — aquatic bacterium that render energy through photosynthesis — evolved and begin releasing atomic number 8 into the sea . This oxygen gradually hoard in the atmosphere in a cognitive process called theGreat Oxidation Event(GOE ) , which took topographic point between 2.4 and 2.1 billion old age ago . newfangled research , however , suggests that aerobic ( O - subject ) bacteria may have emerged long before the GOE .
An outside squad of researchers has reconstructed the evolutionary tree diagram of one of Earth ’s earliest life forms , bring out that bacteria may have adjust to the mien of oxygen long before it was plentiful in our atmosphere . Their piece of work , detailed in astudypublished today in the journal Science , challenges the late assumption that most life prior to the GOE was anaerobic , that is , organism that do n’t need oxygen to hold up .
The researchers used a multidisciplinary approach to remodel an evolutionary tree for bacteria and trace when they adapted to oxygen . This included analyzing geological records , fossil evidence , and over 1,000 diverse bacterial genomes ; applyingphylogenetic reconciliation(comparing the history of two closely intertwined life physical body ) ; and computer molding . According to their evolutionary tree , the last common ascendent of forward-looking bacteria likely survive sometime between 4.4 and 3.9 billion geezerhood ago .
Prochlorococcus marinus, a cyanobacterium.© Luke Thompson from Chisholm Lab and Nikki Watson from Whitehead, MIT, CC0, via Wikimedia Commons
“ This combined coming of using genomic information , fossils , and Earth ’s geochemical history brings new clarity to evolutionary timelines , especially for microbial groups that do n’t have a dodo disk , ” Gergely Szöllősi , a co - writer on the subject area and an evolutionary life scientist from the Okinawa Institute of Science and Technology Graduate University , say in a universitystatement .
Their results suggest that some aerophilic bacteria go forth before the GOE , around 3.22 to 3.25 billion years ago . It ’s likely that these bacterial lineages were the ancestors of cyanobacteria , meaning they develop the ability to metabolize small sum of oxygen before developing photosynthesis . In fact , the enquiry suggests that O adaption may have play a crucial purpose in the phylogenesis of cyanobacteria ’s photosynthetic abilities — and , as a consequence , the changes in Earth ’s atmosphere during the GOE .
The squad ’s approach “ works well for studying the bedspread of aerobic metabolisms and might also be a utilitarian approach for exploring how other traits emerged and interact with the planet ’s shift surround across geological metre , ” say Tom Williams , a computational evolutionary biologist from the University of Bristol and also a co - source on the study .
The study is also a admonisher of the fact that the atmosphere we enjoy today was shaped by gazillion of age of microbic activity .
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