According to a study published by the Imperial College London, microbes could have performed oxygen-producing photosynthesis at least one billion years earlier in the history of the Earth than previously thought.
Oxygen in our planet’s atmosphere is required for complex forms of life, which use it during aerobic respiration to make energy.
Previous studies have revealed that 2.4 billion years ago, levels of oxygen dramatically rose in our planet’s atmosphere, but the reason behind it has been heavily debated.
Some scientists argue that the spike in oxygen levels 2.4 billion years ago can be attributed to the time when organisms called cyanobacteria first evolved.
These organisms were the first to perform oxygen-producing (oxygenic) photosynthesis.
Other experts don’t agree and suggest that cyanobacteria evolved long before 2.4 billion years ago.
However, something happened that prevented oxygen from accumulating in the atmosphere.
It is known that Cyanobacteria can perform a sophisticated form of oxygenic photosynthesis.
It is the same type of photosynthesis that all planets on Earth do today.
This is the reason why experts have theorized that simpler forms of oxygenic photosynthesis may have existed on Earth long before cyanobacteria which resulted in lower oxygen levels available to other life on Earth.
Now, a new study published by scientists from Imperial College London has found that oxygenic photosynthesis arose at least one billion years before cyanobacteria evolved.
The results of their paper were published in the journal Geobiology and show that oxygenic photosynthesis could have evolved very early in our planet’s history.
“We know cyanobacteria are very ancient, but we don’t know exactly how ancient. If cyanobacteria are, for example, 2.5 billion years old, that would mean oxygenic photosynthesis could have started as early as 3.5 billion years ago. It suggests that it might not take billions of years for a process like oxygenic photosynthesis to start after the origin of life,” explained the lead author of the study Dr. Tanai Cardona, from the Department of Life Sciences at Imperial.
This also means that if oxygenic photosynthesis may have evolved early in earth’s history, the probability of complex life emerging on distant alien worlds is quite hight.
Dr. Cardona added: “Usually, the appearance of oxygenic photosynthesis and cyanobacteria are considered to be the same thing. So, to find out when oxygen was produced for the first time researchers have tried to find when cyanobacteria first evolved.
“Our study instead shows that oxygenic photosynthesis likely got started long before the most recent ancestor of cyanobacteria arose. This is in agreement with current geological data that suggests that whiffs of oxygen or localized accumulations of oxygen were possible before three billion years ago.”