The speed with which the Earth rotates on its axis may have played an important role in the amount of oxygen in the atmosphere. This is the conclusion of German and American scientists based on research on microbes.
As the days on Earth became longer, microbes such as blue-green algae began to produce more oxygen through photosynthesis due to several hours of sunlight, the scientists wrote in their article. natural earth sciences. As a result, the oxygen content in the atmosphere has steadily increased, which is important for the development of life on Earth.
Six hours a day
Over the years, the Earth has slowed down on its axis, due in part to the gravitational force between the Earth and the Moon. When the Earth formed about 4.5 billion years ago, a day passed after the sixth hour. More than two billion years later, that is, 21 hours and about 700 million years ago, the Earth has rotated on its axis in the current 24 hours.
For the study, microbes were examined from a stream in Lake Huron, on the border between the United States and Canada. There, in cold, oxygen-poor waters, microbes live in conditions similar to those in the oceans shortly after the formation of the Earth.
In the lab, the researchers exposed the algae to light. This showed that they produce more oxygen the longer they stay in the light, and then the scientists used models to calculate the effect of this on a global scale. They then concluded that long days may have played an essential role in the evolution of life on Earth.
More time to produce oxygen
When the days were shorter, the microbes were less likely to produce oxygen, in part because they were thwarted by other microbes. That changed as the days increased and they had more time to expel oxygen, the scientists wrote.
One of the lead researchers, microbiologist Greyjoy Dick of the University of Michigan, explains that why oxygen levels have exploded at certain points in Earth’s history has long been a question mark.
It was already suspected that microbes played a crucial role in this. “But we don’t know which factors played a role in this and when,” he says. Press release from his university. “Our research shows that the length of the day can answer those patterns and timing.”
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