One of the most important events in the history of the earth is the evolution of photosynthesis. After life gained the ability to obtain energy from light, it no longer relied heavily on the original environment. Life began to become more complex and entered new environments, eventually reshaping the appearance of the earth. Recently, clear evidence from new fossils has pushed photosynthesis back to 1.7 billion years ago.
Tracking the oxygen content of Earth’s atmosphere shows that photosynthesis emerged at least 2.4 billion years ago; tracking today’s genetic variation, the origin of photosynthesis can be traced back to about 3 billion years ago, which is similar to the origin of cyanobacteria, but we have no clear evidence for this Do photosynthetic cells also have a similar age. Some microfossils similar to those of cyanobacteria have been found, but it has not been determined whether they were making the proteins that power photosynthesis.
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Recently, the team of paleomicrobiologist Catherine Demoulin of the University of Liège discovered new thylakoid fossils of blue-green bacteria. Its structure is similar to the structure of oxygen-producing photosynthesis in most modern cyanobacteria and plants. The clear evidence of photosynthesis can be traced back to 1.73 to 1.78 billion years ago.
Thylakoid is a single-membrane sac-like structure in chloroplasts or blue-green algae. It is also the site for photosynthesis and light reactions. The earliest known microfossil evidence of blue-green bacteria is an organism named Eoentophysalis belcherensis, which can be traced back to 2.018 billion years ago, but not all fossil internal structures are intact, and not all blue-green species have thylakoids.
Catherine Demoulin’s team used high-resolution microscopy technology to detect the microfossil structure of the blue-green bacterium Navifusa majensis and discovered the thylakoid membrane. Since the strata from which these fossils were dug can be traced back to 1.75 billion years ago, this represents oxygenic photosynthesis. It must have evolved before then.
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Although we are not yet sure whether the evolution of thylakoids contributed to the Great Oxidation Event, similar ultrastructural analyzes of older microfossils could help answer this question.
new paperPublished in the journal Nature.
(Source of first picture:pixabay）
